runtime.md: Fix sub-bullet indentation #495

grahamwhaley · 2016-06-09T09:42:38Z

The indentation of the sub bullets for the status entries under State were not
indented by the 4 spaces required by markdown. They did not render well in
the pdf, at least with my native build with pandoc v1.13.2. Change them to 4
spaces, which now renders well.

Signed-off-by: Graham Whaley graham.whaley@linux.intel.com

The indentation of the sub bullets for the status entries under State were not indented by the 4 spaces required by markdown. They did not render well in the pdf, at least with my native build with pandoc v1.13.2. Change them to 4 spaces, which now renders well. Signed-off-by: Graham Whaley <graham.whaley@linux.intel.com>

vbatts · 2016-06-09T11:06:51Z

Oh wait, adding spaces makes it better in the PDF?

grahamwhaley · 2016-06-09T11:45:14Z

It does for me - in the html also. Without the spaces it was much less clear that those were sub-points to the previous point. I'm having trouble finding a definitive markdown reference (anybody?), but from the random pages I have found I think the requirement is for four spaces or a tab character to increase the level of indentation.

vbatts · 2016-06-09T11:54:02Z

Yeah. Definitive documentation on stuff lack that is lacking

On Thu, Jun 9, 2016, 06:45 Graham Whaley notifications@github.com wrote:

It does for me - in the html also. Without the spaces it was much less
clear that those were sub-points to the previous point. I'm having trouble
finding a definitive markdown reference (anybody?), but from the random
pages I have found I think the requirement is for four spaces or a tab
character to increase the level of indentation.

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wking · 2016-06-09T16:23:23Z

On Thu, Jun 09, 2016 at 04:45:16AM -0700, Graham Whaley wrote:

I'm having trouble finding a definitive markdown reference (anybody?)…

From 1:

List items may consist of multiple paragraphs. Each subsequent
paragraph in a list item must be indented by either 4 spaces or one
tab…

I expect that's intended to be read with “block element” instead of
“paragraph”, in which case it's the reference you need.

grahamwhaley · 2016-06-10T09:32:13Z

I did a bit more digging. It is slightly more convoluted...
Looking at the Makefile, pandoc is invoked with the 'from' type as 'markdown_github'. I guess that definitively means the spec is formatted in github flavour markdown (I don't think I've seen that specifically noted anywhere else?). If we go find the github markdown reference:
https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists
then it says:
"You can create nested lists by indenting lines by two spaces."

Thus, I checked how the sub-list in runtime.md looked when viewed:

on github web interface (github rendered)
in the generated pdf
in the generated html
for both the master and the submitted patched version.

In the master version, it looks fine when rendered on github, but both the pdf and html render the sub-list as a 'non-bold' list at the same level of indent using the same style of bullets. On my screen/system at least it is hard to tell the difference from the top level list.
In the patched branch the sub-list is indented and uses a different bullet style, which is much clearer.

So, although technically we could stick to the two spaces as per the github_markdown spec, the docs seem to render much better with four spaces.

vbatts · 2016-06-10T14:32:03Z

LGTM
that does make a big difference for the pdf and html docs. Thanks!

wking · 2016-06-10T14:37:19Z

Should we file follow-up PRs for the other instances? For example
[1,2](and I imagine there are more).

vbatts · 2016-06-10T14:40:23Z

I imagine this PR could add more. And image-spec needs to be double checked.

crosbymichael · 2016-06-10T17:41:06Z

LGTM

wking · 2016-06-10T17:48:34Z

On Fri, Jun 10, 2016 at 10:41:16AM -0700, Michael Crosby wrote:

Merged #495.

Follow-up PRs it is 1 ;).

Catch up with 7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [1]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... I expect that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [2]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. [1]: http://daringfireball.net/projects/markdown/syntax#list [2]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists Signed-off-by: W. Trevor King <wking@tremily.us>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also drops the file-descriptor docs from runtime-linux. It's unclear how these apply to runtimes APIs that are not based on the command line / execve, and the functionality is covered by the more tightly scoped LISTEN_FDS wording in the command-line docs. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Hopefully-Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Partially-Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also drops the file-descriptor docs from runtime-linux. It's unclear how these apply to runtimes APIs that are not based on the command line / execve, and the functionality is covered by the more tightly scoped LISTEN_FDS wording in the command-line docs. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also drops the file-descriptor docs from runtime-linux. It's unclear how these apply to runtimes APIs that are not based on the command line / execve, and the functionality is covered by the more tightly scoped LISTEN_FDS wording in the command-line docs. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was recieved and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also drops the file-descriptor docs from runtime-linux. It's unclear how these apply to runtimes APIs that are not based on the command line / execve, and the functionality is covered by the more tightly scoped LISTEN_FDS wording in the command-line docs. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was received and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also drops the file-descriptor docs from runtime-linux. It's unclear how these apply to runtimes APIs that are not based on the command line / execve, and the functionality is covered by the more tightly scoped LISTEN_FDS wording in the command-line docs. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was received and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. * Add a sub-package specs-go/socket. Even though there aren't many new types, these are fairly different from the rest of specs-go and that namespace was getting crowded. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also drops the file-descriptor docs from runtime-linux. It's unclear how these apply to runtimes APIs that are not based on the command line / execve, and the functionality is covered by the more tightly scoped LISTEN_FDS wording in the command-line docs. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was received and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. * Add a sub-package specs-go/socket. Even though there aren't many new types, these are fairly different from the rest of specs-go and that namespace was getting crowded. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also moves the file-descriptor docs from runtime-linux.md into runtime.md and the command-line docs. Both affect runtime authors, but: * The runtime.md entry is more useful for bundle authors than the old wording, because it gives them confidence that the runtime caller will have the power to set these up as they see fit (within POSIX's limits). It is also API-agnostic, so bundle authors know they won't have to worry about which API will be used to launch the container before deciding whether it is safe to rely on runtime-caller file-descriptor control. * The command line entry is more useful for runtime-callers than the old wording, because it tells you how to setup the file descriptors instead of just telling you that they MAY be setup. I moved the bundle-author language from runtime-linux.md to runtime.md because it's relying on POSIX primatives that aren't Linux-specific. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was received and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. * Add a sub-package specs-go/socket. Even though there aren't many new types, these are fairly different from the rest of specs-go and that namespace was getting crowded. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also moves the file-descriptor docs from runtime-linux.md into runtime.md and the command-line docs. Both affect runtime authors, but: * The runtime.md entry is more useful for bundle authors than the old wording, because it gives them confidence that the runtime caller will have the power to set these up as they see fit (within POSIX's limits). It is also API-agnostic, so bundle authors know they won't have to worry about which API will be used to launch the container before deciding whether it is safe to rely on runtime-caller file-descriptor control. * The command line entry is more useful for runtime-callers than the old wording, because it tells you how to setup the file descriptors instead of just telling you that they MAY be setup. I moved the bundle-author language from runtime-linux.md to runtime.md because it's relying on POSIX primitives that aren't Linux-specific. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. Aleksa Sarai also raised concerns over the safety of potentially giving the container process access to terminal ioctl escapes [stdio-ioctl] and feels like the stdio file-descriptor pass-through is surprising [stdio-surprise]. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was received and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. * Add a sub-package specs-go/socket. Even though there aren't many new types, these are fairly different from the rest of specs-go and that namespace was getting crowded. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also moves the file-descriptor docs from runtime-linux.md into runtime.md and the command-line docs. Both affect runtime authors, but: * The runtime.md entry is more useful for bundle authors than the old wording, because it gives them confidence that the runtime caller will have the power to set these up as they see fit (within POSIX's limits). It is also API-agnostic, so bundle authors know they won't have to worry about which API will be used to launch the container before deciding whether it is safe to rely on runtime-caller file-descriptor control. * The command line entry is more useful for runtime-callers than the old wording, because it tells you how to setup the file descriptors instead of just telling you that they MAY be setup. I moved the bundle-author language from runtime-linux.md to runtime.md because it's relying on POSIX primitives that aren't Linux-specific. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having 'create' take a '--console-socket PATH' option (required when process.terminal is true) with a path to a SOCK_SEQPACKET Unix socket for use with the console-socket protocol. The current 'LISTEN_FDS + 3' approach was proposed by Michael Crosby [console-socket-fd], but Trevor doesn't have a clear idea of the motivation for the change and would have preferred '--console-socket FD'. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [console-socket-fd]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-19-21.00.log.html#l-30 [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [stdio-ioctl]: opencontainers#513 (comment) [stdio-surprise]: opencontainers#513 (comment) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

# Commands ## create The --bundle [start-pr-bundle] and --pid-file options and ID argument [runc-start-id] match runC's interface. One benefit of the early-exit 'create' is that the exit code does not conflate container process exits with "failed to setup the sandbox" exits. We can take advantage of that and use non-zero 'create' exits to allow stderr writing (so the runtime can log errors while dying without having to successfully connect to syslog or some such). Trevor still likes the long-running 'create' API because it makes collecting the exit code easier, see the entry under rejected-for-now avenues at the end of this commit message. ### --pid-file You can get the PID by calling 'state' [container-pid-from-state], and container PIDs may not be portable [container-pid-not-portable]. But it's a common way for interfacing with init systems like systemd [systemd-pid], and for this first pass at the command line API folks are ok with some Linux-centrism [linux-centric]. ### Document LISTEN_FDS for passing open file descriptors This landed in runC with [runc-listen-fds], but the bundle-author <-> runtime specs explicitly avoided talking about how this is set (since the bundle-author didn't care about the runtime-caller <-> runtime interface) [runtime-spec-caller-api-agnostic]. This commit steps away from that agnosticism. Trevor left LISTEN_PID [sd_listen_fds,listen-fds-description] out, since he doesn't see how the runtime-caller would choose anything other than 1 for its value. It seems like something that a process would have to set for itself (because guessing the PID of a child before spawning it seems racy ;). In any event, the runC implementation seems to set this to 1 regardless of what systemd passes to it [listen-fds-description]. We've borrowed Shishir's wording for the example [listen-fds-description]. ## state [state-pr] Partially catch up with opencontainers/runtime-spec@7117ede7 (Expand on the definition of our ops, 2015-10-13, opencontainers#225, v0.4.0). The state example is adapted from runtime.md, but we defer the actual specification of the JSON to that file. The encoding for the output JSON (and all standard-stream activity) is covered by the "Character encodings" section. In cases where the runtime ignores the SHOULD (still technically compliant), RFC 7159 makes encoding detection reasonably straightforward [rfc7159-s8.1]. The obsolete RFC 4627 has some hints as well [rfc4627-s3] (although these were dropped in RFC 7518 [rfc7518-aA], probably as a result of removing the constraint that "JSON text" be an object or array [rfc7518-aA]). The hints should still apply to the state output, because we know it will be an object. If that ends up being too dicey and we want to certify runtimes that do not respect their operating-system conventions, we can add an --encoding option later. ## kill Partially catch up with opencontainers/runtime-spec@be594153 (Split create and start, 2016-04-01, opencontainers#384). The interface is based on POSIX [posix-kill], util-linux [util-linux-kill], and GNU coreutils [coreutils-kill]. The TERM/KILL requirement is a minimum portability requirement for soft/hard stops. Windows lacks POSIX signals [windows-signals], and currently supports soft stops in Docker with whatever is behind hcsshim.ShutdownComputeSystem [docker-hcsshim]. The docs we're landing here explicitly allow that sort of substitution, because we need to have soft/hard stop on those platforms but *can't* use POSIX signals. They borrow wording from opencontainers/runtime-spec@35b0e9ee (config: Clarify MUST for platform.os and .arch, 2016-05-19, opencontainers#441) to recommend runtime authors document the alternative technology so bundle-authors can prepare (e.g. by installing the equivalent to a SIGTERM signal handler). # Command style Use imperative phrasing for command summaries, to follow the practice recommended by Python's PEP 257 [pep257-docstring]: The docstring is a phrase ending in a period. It prescribes the function or method's effect as a command ("Do this", "Return that"), not as a description; e.g. don't write "Returns the pathname ...". The commands have the following layout: ### {command name} {one-line description} * *Options:* ... ... * *Exit code:* ... {additional notes} #### Example {example} The four-space list indents follow opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). From [markdown-syntax]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... Trevor expects that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [github-lists]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. # Versioning The command-line interface is largely orthogonal to the config format, and config authors and runtime callers may be entirely different sets of people. Zhang Wei called for more explicit versioning for the CLI [interface-versioning], and the approach taken here follows the approach taken by Python's email package [python-email-version]. Wedging multiple, independently versioned entities into a single repository can be awkward, but earlier proposals to put the CLI in its own repository [separate-repository-proposed] were unsuccessful because compliance testing requires both a CLI and a config specification [separate-repository-refused]. Trevor doesn't think that's a solid reason [separate-repository-refusal-rebutted], but discussion along that line stalled out, so the approach taken here is to keep both independently versioned entities in the same repository. # Global options This section is intended to allow runtimes to extend the command line API with additional options and commands as they see fit without interfering with the commands and options specified in this document. The last line in this section makes it explicit that any later specification (e.g. "MUST print the state JSON to its stdout") do not apply to cases where the caller has included an unspecified option or command (e.g. --format=protobuf). For extensive discussion on this point see [extensions-unspecified]. With regard to the statement "Command names MUST NOT start with hyphens", the rationale behind this decision is to distinguish unrecognized commands from unrecognized options [distinguish-unrecognized-commands] because we want to allow (but not require) runtimes to fail fast when faced with an unrecognized command [optional-fail-fast]. # Long options Use GNU-style long options to avoid ambiguous, one-character options in the spec, while still allowing the runtime to support one-character options with packing. We don't specify one-character options in this spec, because portable callers can use the long form, and not specifying short forms leaves runtimes free to assign those as they see fit. # Character encodings Punt to the operating system for character encodings. Without this, the character set for the state JSON or other command output seemed too ambiguous. Trevor wishes there were cleaner references for the {language}.{encoding} locales like en_US.UTF-8 and UTF-8. But [wikipedia-utf-8,wikipedia-posix-locale] seems too glib, and he can't find a more targetted UTF-8 link than just dropping folks into a Unicode chapter (which is what [wikipedia-utf-8] does): The Unicode Standard, Version 6.0, §3.9 D92, §3.10 D95 (2011) With the current v8.0 (2015-06-17), it's still §3.9 D92 and §3.10 D95. The TR35 link is for: In addition, POSIX locales may also specify the character encoding, which requires the data to be transformed into that target encoding. and the POSIX §6.2 link is for: In other locales, the presence, meaning, and representation of any additional characters are locale-specific. # Standard streams The "MUST NOT attempt to read from its stdin" means a generic caller can safely exec the command with a closed or null stdin, and not have to worry about the command blocking or crashing because of that. The stdout spec for start/delete is more lenient, because runtimes are unlikely to change their behavior because they are unable to write to stdout. If this assumption proves troublesome, we may have to tighten it up later. Aleksa Sarai also raised concerns over the safety of potentially giving the container process access to terminal ioctl escapes [stdio-ioctl] and feels like the stdio file-descriptor pass-through is surprising [stdio-surprise]. # Console socket protocol Based on in-flight work by Aleksa in opencontainers/runc#1018, this commit makes the following choices: * SOCK_SEQPACKET instead of SOCK_STREAM, because this is a message-based protocol, so it seems more natural to use a message-oriented socket type. * A string 'type' field for all messages, so we can add additional message types in the future without breaking backwards compatibility (new console-socket servers will still support old clients). Aleksa favored splitting this identifier into an integer 'type' and 'version' fields [runc-socket-type-version], but I don't see the point if they're both opaque integers without internal structure. And I expect this protocol to be stable enough that it's not worth involving SemVer and its structured versioning. * Response messages, so the client can tell whether the request was received and processed successfully or not. That gives the client a way to bail out if, for example, the server does not support the 'terminal' message type. * Add a sub-package specs-go/socket. Even though there aren't many new types, these are fairly different from the rest of specs-go and that namespace was getting crowded. # Event triggers The "Callers MAY block..." wording is going to be hard to enforce, but with the runC model, clients rely on the command exits to trigger post-create and post-start activity. The longer the runtime hangs around after completing its action, the laggier those triggers will be. For an alternative event trigger approach, see the discussion of an 'event' command in the rejected-for-now avenues at the end of this commit message. # Lifecycle notes These aren't documented in the current runtime-spec, and may no longer be true. But they were true at one point, and informed the development of this specification. ## Process cleanup On IRC on 2015-09-15 (with PDT timestamps): 10:56 < crosbymichael> if the main process dies in the container, all other process are killed ... 10:58 < julz> crosbymichael: I'm assuming what you mean is you kill everything in the cgroup -> everything in the container dies? 10:58 < crosbymichael> julz: yes, that is how its implemented ... 10:59 < crosbymichael> julz: we actually freeze first, send the KILL, then unfreeze so we don't have races ## Container IDs for namespace joiners You can create a config that adds no isolation vs. the runtime namespace or completely joins another set of existing namespaces. It seems odd to call that a new "container", but the ID is really more of a process ID, and less of a container ID. The "container" phrasing is just a useful hint that there might be some isolation going on. And we're always creating a new "container process" with 'create'. # Other changes This commit also moves the file-descriptor docs from runtime-linux.md into runtime.md and the command-line docs. Both affect runtime authors, but: * The runtime.md entry is more useful for bundle authors than the old wording, because it gives them confidence that the runtime caller will have the power to set these up as they see fit (within POSIX's limits). It is also API-agnostic, so bundle authors know they won't have to worry about which API will be used to launch the container before deciding whether it is safe to rely on runtime-caller file-descriptor control. * The command line entry is more useful for runtime-callers than the old wording, because it tells you how to setup the file descriptors instead of just telling you that they MAY be setup. I moved the bundle-author language from runtime-linux.md to runtime.md because it's relying on POSIX primitives that aren't Linux-specific. # Avenues pursued but rejected (for now) * Early versions of this specification had 'start' taking '--config' and '--runtime', but this commit uses '--bundle' [start-pr-bundle]. The single config file change [single-config-proposal] went through, but Trevor would also like to be able to pipe a config into the 'funC start' command (e.g. via a /dev/fd/3 pseudo-filesystem path) [runc-config-via-stdin], and he has a working example that supports this without difficulty [ccon-config-via-stdin]. But since [runc-bundle-option] landed on 2015-11-16, runC has replaced their --config-file and --runtime-file flags with --bundle, and the current goal of this API is "keeping as much similarity with the existing runC command-line as possible", not "makes sense to Trevor" ;). It looks like runC was reacting [runc-required-config-file] to strict wording in the spec [runtime-spec-required-config-file], so we might be able to revisit this if/when we lift that restriction. * Having 'start' (now 'create') take a --state option to write state to a file [start-pr-state]. This is my preferred approach to sharing container state, since it punts a persistent state registry to higher-level tooling [punt-state-registry]. But runtime-spec currently requires the runtime to maintain such a registry [state-registry], and we don't need two ways to do that ;). On systems like Solaris, the kernel maintains a registry of container IDs directly, so they don't need an external registry [solaris-kernel-state]. * Having 'start' (now 'create') take an --id option instead of a required ID argument, and requiring the runtime to generate a unique ID if the option was not set. When there is a long-running host process waiting on the container process to perform cleanup, the runtime-caller may not need to know the container ID. However, runC has been requiring a user-specified ID since [runc-start-id], and this spec follows the early-exit 'create' from [runc-create-start], so we require one here. We can revisit this if we regain a long-running 'create' process. * Having 'create' take a '--console-socket PATH' option (required when process.terminal is true) with a path to a SOCK_SEQPACKET Unix socket for use with the console-socket protocol. The current 'LISTEN_FDS + 3' approach was proposed by Michael Crosby [console-socket-fd], but Trevor doesn't have a clear idea of the motivation for the change and would have preferred '--console-socket FD'. * Having a long-running 'create' process. Trevor is not a big fan of this early-exit 'create', which requires platform-specific magic to collect the container process's exit code. The ptrace idea in this commit is from Mrunal [mrunal-ptrace]. Trevor has a proposal for an 'event' operation [event] which would provide a convenient created trigger. With 'event' in place, we don't need the 'create' process exit to serve as that trigger, and could have a long-running 'create' that collects the container process exit code using the portable waitid() family. But the consensus after this week's meeting was to table that while we land docs for the runC API [mimic-runc]. * Having a 'version' command to make it easy for a caller to report which runtime they're using. But we don't have a use-case that makes it strictly necessary for interop, so we're leaving it out for now [no-version]. * Using 'sh' syntax highlighting [syntax-highlighting] for the fenced code blocks. The 'sh' keyword comes from [linguist-languages]. But the new fenced code blocks are shell sessions, not scripts, and we don't want shell-syntax highlighting in the command output. [ccon-config-via-stdin]: https://github.com/wking/ccon/tree/v0.4.0#configuration [console-socket-fd]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-10-19-21.00.log.html#l-30 [container-pid-from-state]: https://github.com/opencontainers/runtime-spec/pull/511/files#r70353376 Subject: Add initial pass at a cmd line spec [container-pid-not-portable]: opencontainers#459 Subject: [ Runtime ] Allow for excluding pid from state [coreutils-kill]: http://www.gnu.org/software/coreutils/manual/html_node/kill-invocation.html [distinguish-unrecognized-commands]: https://github.com/wking/oci-command-line-api/pull/8/files#r46898167 Subject: Clarity for commands vs global options [docker-hcsshim]: https://github.com/docker/docker/pull/16997/files#diff-5d0b72cccc4809455d52aadc62329817R230 moby/moby@bc503ca8 (Windows: [TP4] docker kill handling, 2015-10-12, moby/moby#16997) [event]: opencontainers#508 Subject: runtime: Add an 'event' operation for subscribing to pushes [extensions-unspecified]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-27.log.html#t2016-07-27T16:37:56 [github-lists]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists [interface-versioning]: opencontainers#513 (comment) [linguist-languages]: https://github.com/github/linguist/blob/master/lib/linguist/languages.yml [linux-centric]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-39 [listen-fds-description]: opencontainers/runc#231 (comment) Subject: Systemd integration with runc, for on-demand socket activation [markdown-syntax]: http://daringfireball.net/projects/markdown/syntax#list [mimic-runc]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-13-17.03.log.html#l-15 [mrunal-ptrace]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/%23opencontainers.2016-07-13.log.html#t2016-07-13T18:58:54 [no-version]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-75 [optional-fail-fast]: wking/oci-command-line-api@527f3c6#commitcomment-14835617 Subject: Use RFC 2119's keywords (MUST, MAY, ...) [pep257-docstring]: https://www.python.org/dev/peps/pep-0257/#one-line-docstrings [posix-kill]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/kill.html [punt-state-registry]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2015/opencontainers.2015-12-02-18.01.log.html#l-79 [python-email-version]: https://docs.python.org/3/library/email.html#package-history [rfc4627-s3]: https://tools.ietf.org/html/rfc4627#section-3 [rfc7158-aA]: https://tools.ietf.org/html/rfc7158#appendix-A RFC 7518 is currently identical to 7519. [rfc7159-s8.1]: https://tools.ietf.org/html/rfc7159#section-8.1 [runc-bundle-option]: opencontainers/runc#373 Subject: adding support for --bundle [runc-config-via-stdin]: opencontainers/runc#202 Subject: Can runc take its configuration on stdin? [runc-listen-fds]: opencontainers/runc#231 Subject: Systemd integration with runc, for on-demand socket activation [runc-required-config-file]: opencontainers/runc#310 (comment) Subject: specifying a spec file on cmd line? [runc-socket-type-version]: opencontainers/runc#1018 (comment) Subject: Consoles, consoles, consoles. [runc-start-id]: opencontainers/runc#541 opencontainers/runc@a7278cad (Require container id as arg1, 2016-02-08, opencontainers/runc#541) [runtime-spec-caller-api-agnostic]: opencontainers#113 (comment) Subject: Add fd section for linux container process [runtime-spec-required-config-file]: https://github.com/opencontainers/runtime-spec/pull/210/files#diff-8b310563f1c6f616aa98e6aeffc4d394R14 106ec2d (Cleanup bundle.md, 2015-10-02, opencontainers#210) [sd_listen_fds]: http://www.freedesktop.org/software/systemd/man/sd_listen_fds.html [separate-repository-proposed]: opencontainers#513 (comment) [separate-repository-refused]: opencontainers#513 (comment) [separate-repository-refusal-rebutted]: opencontainers#513 (comment) [single-config-proposal]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/0QbyJDM9fWY Subject: Single, unified config file (i.e. rolling back specs#88) Date: Wed, 4 Nov 2015 09:53:20 -0800 Message-ID: <20151104175320.GC24652@odin.tremily.us> [solaris-kernel-state]: wking/oci-command-line-api#3 (comment) Subject: Drop exec, pause, resume, and signal [start-pr-bundle]: wking/oci-command-line-api#11 Subject: start: Change --config and --runtime to --bundle [start-pr-state]: wking/oci-command-line-api#14 Subject: start: Add a --state option [state-pr]: wking/oci-command-line-api#16 Subject: runtime: Add a 'state' command [state-registry]: https://github.com/opencontainers/runtime-spec/pull/225/files#diff-b84a8d65d8ed53f4794cd2db7e8ea731R61 7117ede (Expand on the definition of our ops, 2015-10-13, opencontainers#225) [stdio-ioctl]: opencontainers#513 (comment) [stdio-surprise]: opencontainers#513 (comment) [syntax-highlighting]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting [systemd-pid]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/2016/opencontainers.2016-07-20-21.03.log.html#l-69 [util-linux-kill]: http://man7.org/linux/man-pages/man1/kill.1.html [wikipedia-utf-8]: https://en.wikipedia.org/wiki/UTF-8 [wikipedia-posix-locale]: https://en.wikipedia.org/wiki/Locale#POSIX_platforms [windows-singals]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/PlGKu7QUwLE Subject: Fwd: Windows support for OCI stop/signal/kill (runtime-spec#356) Date: Thu, 26 May 2016 11:03:29 -0700 Message-ID: <20160526180329.GL17496@odin.tremily.us> Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com> Hopefully-Signed-off-by: Mike Brown <brownwm@us.ibm.com> Signed-off-by: W. Trevor King <wking@tremily.us> Reviewed-by: Jesse Butler <jeeves.butler@gmail.com>

Following opencontainers/runtime-spec@7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers/runtime-spec#495). From [1]: List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either 4 spaces or one tab... I expect that's intended to be read with "block element" instead of "paragraph", in which case it applies to nested lists too. And while GitHub supports two-space indents [2]: You can create nested lists by indenting lines by two spaces. it seems that pandoc does not. [1]: http://daringfireball.net/projects/markdown/syntax#list [2]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#lists Signed-off-by: W. Trevor King <wking@tremily.us>

The only discussion related to this is in [1,2], where the relationship between oomScoreAdj and disableOOMKiller is raised. But since 429f936 (Adding cgroups path to the Spec, 2015-09-02, opencontainers#137) resources has been tied to cgroups, and oomScoreAdj is not about cgroups. For example, we currently have (in config-linux.md): You can configure a container's cgroups via the resources field of the Linux configuration. I suggested we move the property from linux.resources.oomScoreAdj to linux.oomScoreAdj so config authors and runtimes don't have to worry about what cgroupsPath means if the only entry in resources is oomScoreAdj. Michael responded with [4]: If anything it should probably go on the process So that's what this commit does. I've gone with the four-space indents here to keep Pandoc happy (see 7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495), but have left the existing entries in this list unchanged to reduce churn. [1]: opencontainers#236 [2]: opencontainers#292 [3]: opencontainers#137 [4]: opencontainers#782 (comment) Signed-off-by: W. Trevor King <wking@tremily.us>

…gain) Roll back the genericization from 718f9f3 (minor narrative cleanup regarding config compatibility, 2017-01-30, opencontainers#673). Lifting the restriction there seems to have been motivated by "Solaris supports capabilities", but that was before the split into a capabilities object which happened in eb114f0 (Add ambient and bounding capability support, 2017-02-02, opencontainers#675). It's not clear if Solaris supports ambient caps, or what Solaris API rlimits or noNewPrivileges were punting to [1]. And John Howard has recently confirmed that Windows does not support capabilities and is unlikely to do so in the future [2]. John's statement didn't directly address rlimits or noNewPrivileges, but we can always restore any of these properties to the Solaris/Windows platforms if/when we get docs about which API we're punting to on those platforms. Also add some backticks, remove the hyphens in "OPTIONAL) - the", standardize lines I touch to use "the process" [3], and use four-space indents here to keep Pandoc happy (see 7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). [1]: opencontainers#673 (comment) [2]: opencontainers#810 (comment) [3]: opencontainers#809 (comment) Signed-off-by: W. Trevor King <wking@tremily.us>

Roll back the genericization from 718f9f3 (minor narrative cleanup regarding config compatibility, 2017-01-30, opencontainers#673). Lifting the restriction there seems to have been motivated by "Solaris supports capabilities", but that was before the split into a capabilities object which happened in eb114f0 (Add ambient and bounding capability support, 2017-02-02, opencontainers#675). It's not clear if Solaris supports ambient caps, or what Solaris API noNewPrivileges were punting to [1]. And John Howard has recently confirmed that Windows does not support capabilities and is unlikely to do so in the future [2]. He also confirmed that Windows does not support rlimits [3]. John's statement didn't directly address noNewPrivileges, but we can always restore any of these properties to the Solaris/Windows platforms if/when we get docs about which API we're punting to on those platforms. Also add some backticks, remove the hyphens in "OPTIONAL) - the", standardize lines I touch to use "the process" [4], and use four-space indents here to keep Pandoc happy (see 7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, opencontainers#495). [1]: opencontainers#673 (comment) [2]: opencontainers#810 (comment) [3]: opencontainers#835 (comment) [4]: opencontainers#809 (comment) Signed-off-by: W. Trevor King <wking@tremily.us>

The Markdown spec is liberal for the first paragraph [1]: > To make lists look nice, you can wrap items with hanging > indents... But if you want to be lazy, you don’t have to... However, it's a bit more strict about subsequent paragraphs [1]: > List items may consist of multiple paragraphs. Each subsequent > paragraph in a list item must be indented by either 4 spaces or one > tab: That doesn't matter for our use here, because all of our entries are single-paragraph. But runtime-spec has been bitten by Pandoc strictness for multiple paragraphs before [2], and their RELEASES.md has used four-space indents since [3]. By adopting the stricter behavior here, we make it easier for OCI Projects to stay synchronized with the template while maintaining their stricter local conventions. OCI Projects that do not have strict local conventions probably don't care either way. [1]: https://daringfireball.net/projects/markdown/syntax#list [2]: opencontainers/runtime-spec#495 [3]: opencontainers/runtime-spec#846 Signed-off-by: W. Trevor King <wking@tremily.us>

crosbymichael merged commit 6de52a7 into opencontainers:master Jun 10, 2016

wking mentioned this pull request Sep 7, 2016

layer: revamp for readability opencontainers/image-spec#255

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This was referenced Sep 19, 2016

[Runtime] Fix formatting and clarify status values #578

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config: reformat and add optional/required opencontainers/image-spec#333

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wking mentioned this pull request Nov 3, 2016

image-layout: describe an OPTIONAL index opencontainers/image-spec#438

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wking mentioned this pull request Nov 16, 2016

Clean-up spec to remove non-spec-ish items opencontainers/image-spec#458

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wking mentioned this pull request Mar 10, 2017

config-linux.md: fix seccomp #706

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This was referenced May 10, 2017

config.md: format changes #724

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Clarify root path #820

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wking mentioned this pull request May 18, 2017

config: Make capabilities, noNewPrivileges, and rlimits Linux-only (again) #835

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wking mentioned this pull request Sep 11, 2017

Add vTPM specification #920

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wking mentioned this pull request Apr 6, 2018

*: Use four-space indents for list-entry continuation opencontainers/project-template#54

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wking mentioned this pull request Jun 18, 2018

config-linux: describe more about rootfs mount propagation #975

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runtime.md: Fix sub-bullet indentation #495

runtime.md: Fix sub-bullet indentation #495

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runtime.md: Fix sub-bullet indentation #495

runtime.md: Fix sub-bullet indentation #495

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