Compare to similar tools

[srid]

Rendered

• What other tools should we compare with?
• What other aspects should we mention?

This table is just a start, and not complete.

[srid]

cc @roberth for ideas, especially in regards to the aspects. Currently, we have 'pure flakes', 'multiple services', 'sharing' and 'flake apps' (devenv doesn't produce runnable packages, as far as I can tell), etc.

[srid]

@shivaraj-bh To substantiate our "share services across flakes", we probably need to document it first.

[srid]

This maybe inaccurate.

cf. https://devenv.sh/guides/using-with-flake-parts/#import-a-devenv-module

But I haven't used devenv enough to say if its module system works without any idiosyncratic shortcomings.

[shivaraj-bh]

Based on what I see, if you are able to import a module, you should be able to share services even using devenv.

[shivaraj-bh]

And I tried it out:

Here’s the perSystem block from my flake:

And this is the devenv-module.nix:

I do use nix develop —impure followed by devenv up to run them but in terms of sharing services, it works, i.e if you are willing to stick to devenv cli.

[shivaraj-bh]

Although it allows sharing modules between flakes like above, you can’t really share it within the flake to an extent we do in Nammayatri, to provide nix run #load-test-dev, which adds a bunch of processes of its own after sharing the entire backend configuration of nammayatri that is started via nix run .#run-mobility-stack-dev.

In short, devenv allows you to create and merge processes declaratively but all these processes belong to the same group, you can’t define two sets of different groups with a few/all distinct processes.

[srid]

The screenshots you posted above show modular import of devenv config, not devenv services. ie., we can't do the following, right?

devenv.shells.default = {
  services = {
    imports = [ ./mymod.nix ];
    myservice.enable = true;
  };
};

Which explains why you can't compose and share services per se, and must create modules for whole devenv config.

[shivaraj-bh]

we can't do the following, right?

Yes, hope I haven’t missed something. Let me give it one more shot to be certain, don’t want to make false claims because of missing some details.

[srid]

@shivaraj-bh https://discord.com/channels/1036369714731036712/1036369758024650792/1215626814710620190

[srid]

I haven't gotten any clear and unambiguous response from the devenv community, so let's just merge this. If they correct us by providing an example, we can change the README obviously.

[srid]

From https://devenv.sh/guides/using-with-flake-parts/

If you're familiar with the Nix language and ecosystem, devenv can be used without the devenv CLI by integrating into Nix Flakes using flake-parts.

But the page doesn't explain how exactly one starts devenv services without using its CLI.

[shivaraj-bh]

In the flake I created here, I explored the flake in nix repl, and these are the packages it exports:

nix-repl> packages.x86_64-linux.
packages.x86_64-linux.container-processes  packages.x86_64-linux.default
packages.x86_64-linux.container-shell      packages.x86_64-linux.devenv-up

[shivaraj-bh]

But I can’t seem to be able to nix run it:

❯ nix run .#devenv-up --impure
warning: Git tree '/home/shivaraj/oss/devenc' is dirty
trace: warning: getExe: Package "cowsay-3.7.0" does not have the meta.mainProgram attribute. We'll assume that the main program has the same name for now, but this behavior is deprecated, because it leads to surprising errors when the assumption does not hold. If the package has a main program, please set `meta.mainProgram` in its definition to make this warning go away. Otherwise, if the package does not have a main program, or if you don't control its definition, use getExe' to specify the name to the program, such as lib.getExe' foo "bar".
error: unable to execute '/nix/store/67lf41ig3sf8z4i6lnigfn4c0icyb830-devenv-up/bin/devenv-up': Not a directory

Probably it doesn’t have a bin output

[shivaraj-bh]

This works fine: ❯ nix build .#devenv-up —impure

And produces a result whose contents are:

❯ cat /nix/store/67lf41ig3sf8z4i6lnigfn4c0icyb830-devenv-up
#!/nix/store/087167dfxal194pm54cmcbbxsfy3cjgn-bash-5.2p26/bin/bash


/nix/store/lb2b16q8kc3xynj27d25sahhq95ph43h-process-compose-0.88.0/bin/process-compose --config /nix/store/vhxxz7j5bjlyi0ggfx4dlcf9an61p09q-process-compose.yaml \
  --port ${PC_HTTP_PORT:-9999} \
  --tui=${PC_TUI_ENABLED:-1} \
  up "$@" &


if [[ ! -d "$DEVENV_STATE" ]]; then
  mkdir -p "$DEVENV_STATE"
fi

stop_up() {
  echo "Stopping processes..."
  kill -TERM $(cat "$DEVENV_STATE/devenv.pid")
  rm "$DEVENV_STATE/devenv.pid"
  wait

  echo "Processes stopped."
}

trap stop_up SIGINT SIGTERM

echo $! > "$DEVENV_STATE/devenv.pid"

wait

[shivaraj-bh]

But when I try to run it, postgres service never starts, it just times out and fails with:

❯ ./result
mkdir: cannot create directory ‘’: No such file or directory
./result: line 25: /devenv.pid: Permission denied

[shivaraj-bh]

But the same configuration works (including postgres starting successfully) when I do nix develop —impure and then devenv up

[shivaraj-bh]

If I run ./result after removing process.implementation = “process-compose”, it uses honcho by default , which seems to work fine.

I was able to execute queries using psql:

shivaraj=# create table id(id int);
CREATE TABLE
shivaraj=# \dt
        List of relations
 Schema | Name | Type  |  Owner
--------+------+-------+----------
 public | id   | table | shivaraj
(1 row)

[shivaraj-bh]

But when I try to run it, postgres service never starts, it just times out and fails with:

❯ ./result
mkdir: cannot create directory ‘’: No such file or directory
./result: line 25: /devenv.pid: Permission denied

This is because of not exporting DEVENV_STATE, because I am no longer in devShell, I will have to do it manually:

 DEVENV_STATE=$(pwd) ./result

But even after that I couldn’t get it running using the process-compose implementation without being in the devShell

[srid]

In conclusion, we can confidently say that devenv doesn't support running services (nevermind individual process groups) as a flake app.

[shivaraj-bh]

Looks like it, yes

[srid]

This is what it looks likes right now:

Anything that needs changing?

[shivaraj-bh]

IMO adding an example each for “Share services” and “Reusable services” would be useful.

[shivaraj-bh]

Right, you had mentioned this earlier: #135 (comment)

That’s something I can work on adding.

[shivaraj-bh]

@shivaraj-bh To substantiate our "share services across flakes", we probably need to document it first.

Here’s an example: #137

Once we confirm on the example, I will also flesh out the a doc for this.

[srid]

Merging. Let's make follow-up edits in separate PRs.