Add pprof support to ark server

[ncdc]

Fixes #85

There is a new ark server flag: --profiler-address. It defaults to localhost:6060. This means by default it's only accessible if you use kubectl port-forward, but you can change it to something like :6060 and put a service + ingress in front if you want to make it publicly accessible. There is no authentication for it at this time.

This does not add pprof support for plugin processes. Those tend to be relatively short-lived. If needed, in the future we could add some sort of debugging flag that would capture various pprof data from plugin processes and store it in files local to the ark server pod, and they could be retrieved after the fact by hand using kubectl cp or some other mechanism.

[ncdc]

Closing for now. Will reopen if/when necessary.

[ncdc]

I have a test image, ncdc/ark:pprof, with this PR. You can use kubectl -n heptio-ark port-forward deploy/ark 6060 and then access the pprof page at http://localhost:6060/debug/pprof/.

[skriss]

LGTM. @nrb pls review

[skriss]

@wwitzel3 one thing I'm realizing is that we're gonna end up with a lot of merge conflicts in CHANGELOG.md since every concurrent PR (e.g. this one) will be trying to add a line in the same place. Any ideas?

[ncdc]

Separate file per entry?

…

On Tue, Dec 4, 2018 at 4:16 PM Steve Kriss ***@***.***> wrote: @wwitzel3 <https://github.com/wwitzel3> one thing I'm realizing is that we're gonna end up with a lot of merge conflicts in CHANGELOG.md since every concurrent PR (e.g. this one) will be trying to add a line in the same place. Any ideas? — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#234 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAABYm__6tG4S1l74YhX0c3fCtvVOzVAks5u1uYogaJpZM4QyqQD> .

[skriss]

Yeah, I think that's what restic does

[nrb]

Either separate files or delay until ready to merge, but I don't like that.

OpenStack used reno for making the files and managing merges at release time; not advocating it's use here, but something to think about for tooling. https://docs.openstack.org/reno/latest/

[nrb]

LGTM once the changelog conflict is resolved.

[nrb]

@skriss Looks like restic does it all in the main file.

If your pull request changes anything that users should be aware of (a bugfix, a new feature, ...) please add an entry to the file 'CHANGELOG.md'. It will be used in the announcement of the next stable release. While writing, ask yourself: If I were the user, what would I need to be aware of with this change.

[skriss]

@nrb their PR template has you add a changelog entry here: https://github.com/restic/restic/tree/master/changelog/unreleased

With a new file per PR. This is definitely what I did for the one or two PRs I submitted to restic. Then the maintainer updates CHANGELOG.md once per release. Guessing that the CONTRIBUTING.md is just out of date.

[wwitzel3]

Having an changelog/unreleased folder with a file per PR is easy and common across a lot of projects. I will go ahead and make a new PR that updates the root CHANGELOG.md and our CONTRIBUTING.md.

I'll ticket that up and get that updated. In the meantime, @ncdc if you want to just create the unreleased folder under changelog and add your entry there, I'll take care of the rest.

[ncdc]

I've added the unreleased folder and an initial attempt at an entry for this PR. I went with the "easy" approach for now (see discussion at #1112 (comment))