Support multiple build contexts

[ciaranmcnulty]

Dockerfile 1.4 supports multiple build contexts - a way to specify them when building in compose would be great

I'd suggest something like:

services:
   myapp:
    build:
        contexts:
            additional: ../foo
            deps: https://github.com/myvendor/deps
            dist: https://somedistro.info/download/latest.tar.gz

Being able to drive this from environment / .env could be very powerful

[nrontsis]

Is there a roadmap or any updates on this? Thanks!

[felipecrs]

I suppose the ability to link targets/services to create build pipelines as in buildx bake should also be accounted. :)

[lmoesch]

Are there any concrete plans on this issue yet?

[alexania]

Alternately, perhaps the ability to pass additional args to the build command? That way you could pass --build-context manually while waiting for the compose specification to support it natively.

[knpwrs]

This would solve the long-standing issue of having shared code between multiple containers in a docker compose project. Would the team be open to a pull request to implement this?

[kdubuc]

With buildx bake I can build image from a compose file (see https://docs.docker.com/build/customize/bake/compose-file) :

# docker-compose.yml
services:
  service_name:
    build:
      context: .
      x-bake:
        contexts:
          context1: path
          context2: path

And build with docker buildx bake -f docker-compose.yml service_name

But I don't know if we can up a service using buildx / bake.

[ciaranmcnulty]

@kdubuc we can't; you can have a hybrid setup where you use bake for build and compose for running, but it'd be nice to have it all in compose

[mbielanczuk]

This would be a much appreciated feature, are there any updates/plans to implement it?

[glours]

There is a PR on the Compose spec for supporting additional contexts during build. It seems to be ready to be merge soon

[laurazard]

Yup. Follow up PR on compose-go here, and I have the rest of the implementation ready to go for when that gets merged. Should be quick after the spec PR gets merged.