Adding more tags to a single bake target

[0yi0]

I'm using matrix to generate multiple images like

target "base" {
  matrix = {
    version = ["20.04", "22.04", "24.04"]
  }
  name = "ubuntu-${replace(version, ".", "")}"
  tags = ["my/image:ubuntu-${version}"]
  ...
}

Is there any way to re-tag images without overriding original tags like we do in command line?

docker tag my/image:ubuntu-24.04 my/image:ubuntu-latest

I currently push docker images directly with docker/bake-action. I think it can be done like

- uses: docker/bake-action@v5
  with:
    push: true
    set: |
      ubuntu-2404.tags = [<original tags ...>, "my/image:ubuntu-latest"]

But in this way I need to rewrite the whole array instead of just adding a tag.

Is there any way to achieve something like

- uses: docker/bake-action@v5
  with:
    push: true
    set: |
      ubuntu-2404.tags += ["my/image:ubuntu-latest"]

So that we don't need to touch any existing tags?

Alt solutions (My workarounds)

I'm currently using a new target as the original one as its context.

target "latest" {
  inherits = ["ubuntu-2404"]
  contexts = {
    "my/image:ubuntu-24.04" = "target:ubuntu-2404"
  }
  tags = ["my/image:ubuntu-latest"]
}

I also saw a 4yo discussion docker/buildx#427 to allow optional tagging.

[polarathene]

Is there any way to achieve something like

- uses: docker/bake-action@v5
  with:
    push: true
    set: |
      ubuntu-2404.tags += ["my/image:ubuntu-latest"]

Does that not work? It is supported with --set via the CLI 🤔

You can use docker/metadata-action to manage tags as it has various conveniences for generating tags based on conditions, and then you just pass that output to docker/bake-action (it's a separate bake target with this data, so you must modify your target to inherit it for the tags, or use target.docker-metadata-action.tags to reference the value.

---

UPDATE: It was answered here that you can use that --set syntax with += in the action too.

[0yi0]

It was over a year and docker/bake-action is now @v6.9.0. I think I should close this one.
Thanks for your information. 😃

[crazy-max]

Yes indeed, += operator to append with overrides is supported since Buildx v0.22.0: docker/buildx#3031

More info: https://docs.docker.com/reference/cli/docker/buildx/bake/#set