Handle multiple prefixes with Bake

Let’s say I have a Dockerfile like so:

FROM debian:latest AS debian

[...]


# debian is the default
FROM debian


FROM ubuntu:latest AS ubuntu

[...]


FROM alpine:latest AS alpine

[...]

And a docker-bake.hcl like so:

group "default" {
  targets = ["debian"]
}

group "all" {
  targets = ["debian", "ubuntu", "alpine", "centos"]
}

target "base" {
  context = "."
}

target "debian" {
  inherits = ["base"]
  target = "debian"
}

target "ubuntu" {
  inherits = ["base"]
  target = "ubuntu"
}

target "alpine" {
  inherits = ["base"]
  target = "alpine"
}

Any suggestions on how could I integrate the Metadata Action with the Bake Action so I would have tags generated with prefixes like:

my-image:latest # debian
my-image:debian
my-image:ubuntu
my-image:alpine

And of course, tagging with semver like my-image:alpine-1.1.0.

[sandhose]

I had this exact problem, and figured that the bake files are just JSON files that can be merged with jq. This is how I solved it, by running the action twice and merging the files:

https://github.com/matrix-org/matrix-authentication-service/blob/1df5cf42e32abaeedddc504afeb431d77154f78f/.github/workflows/check.yaml#L317-L345

     - name: Docker meta
       id: meta
       uses: docker/metadata-action@v3
       with:
         images: ...
         bake-target: docker-metadata-action
         tags: ...

     - name: Docker meta (debug variant)
       id: meta-debug
       uses: docker/metadata-action@v3
       with:
         images: ...
         bake-target: docker-metadata-action-debug
         tags: ...

     - name: Merge buildx bake files
       run: |
           jq -s '.[0] * .[1]' ${{ steps.meta.outputs.bake-file }} ${{ steps.meta-debug.outputs.bake-file }} > docker-bake.override.json

That way I have two different targets filled in my bake file: https://github.com/matrix-org/matrix-authentication-service/blob/1df5cf42e32abaeedddc504afeb431d77154f78f/docker-bake.hcl#L4-L6

[fourbytes]

I’m trying to do something similar to this. I have a repo with multiple micro-services, each service is pushed to a registry (ghcr.io/<owner>/<project>/<service>:<tag>) and it doesn’t seem possible to use this metadata data action to set the tags for each service at the moment. I could do it with multiple steps however that would slow down the build as they’d have to run sequentially.