Support optional packages

[itsdalmo]

What problem are you trying to solve?

I'm using devbox and direnv to encapsulate my development environment, and using the devbox-install-action and direnv to set replicate the environment for tests in Github actions also. This has been working great, however my Github actions steps are installing a lot of dev dependencies that are not needed by the CI, and restoring the cache with all this bloat is slowing down Github actions.

What solution would you like?

I wanted to include: another devbox.json file the way we can include a plugin right now, so that I could compose devbox configs. However, fundamentally this is just a feature request to be able to specify optional packages, so that certain packages don't get installed in my CI jobs.

Alternatives you've considered

I tried to create two files:

• devbox.ci.json (i.e. the minimal dependencies for running our tests)
• devbox.json (full development environment)

Then I tried to include: the devbox.ci.json in the other, and discovered that include was reserved for plugins. I then tried to create a subfolder devbox/ci/plugin.json and using that as the include in both devbox.ci.json (otherwise empty) and devbox.json, however I ran into a couple of problems:

1. When I use devbox shell --config devbox.ci.json it updates the devbox.lock (not devbox.ci.lock).
2. I have a path:./my/flake#bin in my plugin.json is now relative to the devbox.json file that includes it, and not the plugin itself, which means I can't move one of the devbox.json files to a separate directory.

[aaomidi]

I agree with this being necessary. Just restoring our pretty reasonable sized devbox file takes ~40 seconds (and its just disk speed at this point, not network speed).