Expose buildpack detection as a command

[Tashows]

I am working on a feature and want to be able to call this via dokku. Ideally dokku buildpacks:detect app_name, alternatively via a custom plugin. Let me know which one would make more sense.

Basically just needs to run something like this:

docker run --rm \
  -v "$APP_ROOT:/tmp/app" \
  ${BUILDPACK_DETECT_OUTPUT:+-e BUILDPACK_DETECT_OUTPUT="$BUILDPACK_DETECT_OUTPUT"} \
  gliderlabs/herokuish \
  /bin/herokuish buildpack detect /tmp/app
;;

If this is moved into buildpacks (or a separate) plugin, then the part that checks out a potential bare git repo, could probably be moved there as well and just run before the command above. Not sure about permissions complications.

[josegonzalez]

Yeah I feel like the part that checks out the repo should be separate from here, can you make that change?

[Tashows]

Cleared that out and also added handling json output when multiple buildpacks are detected.

Would you like me to add the relevant functionality to utilize this in the core buildpacks plugin? Or would you rather I create a separate plugin?

[Tashows]

It might be useful to add "url", "slug" (eg. "heroku/ruby") or even "version" (eg. "v321") to the json output, but I am not sure how to get these. If that makes sense, do you have any suggestions I can look into?

[josegonzalez]

I'd actually rather not have this tool expose json output. Mind removing that?

The detected buildpack will be in the buildpack-url and the buildpack-version file: https://github.com/gliderlabs/herokuish/blob/master/buildpacks/buildpack-clojure/buildpack-url https://github.com/gliderlabs/herokuish/blob/master/buildpacks/buildpack-clojure/buildpack-version

[Tashows]

Cleared that up as well. It was optional and nice-to-have really, but I get it.

Let me know if you'd rather have this functionality utilized in the core "buildpacks" dokku plugin (so we can run dokku buildpacks:detect app_name), or I make a separate plugin.

Thanks for the comments.

[josegonzalez]

Mind adding a test for this functionality?