Allow the images input to be empty, which outputs just the raw tags

[jasondamour]

Addresses #212

[jasondamour]

@crazy-max Can I get eyes on this before I resolve conflicts?

[jasondamour]

Intended usage is for build tools which only take the tags as input, not the full image url. For example, this is working today:

    - name: Docker Metadata
      id: docker-metadata
      uses: jasondamour/metadata-action@4a2a7878d3f53d548dc904024c8873d1fdb152be
      with:
        sep-tags: ','
        sep-labels: ','
        tags: ${{ env.DOCKER_TAGS_CONFIG }}
    - name: Maven Build
      run: >
        mvn jib:build
        -Djib.to.tags=${{ steps.platfom-svc-docker-metadata.outputs.tags }}
        -Djib.container.labels=${{ steps.platfom-svc-docker-metadata.outputs.labels }}

[tatality173]

jasondamour:empty-images

[tatality173]

// docker-bake.hcl
target "docker-metadata-action" {}

target "build" {
inherits = ["docker-metadata-action"]
context = "./"
dockerfile = "Dockerfile"
platforms = [
"linux/amd64",
"linux/arm/v6",
"linux/arm/v7",
"linux/arm64",
"linux/386"
]
}

[jasondamour]

@tatality173 ??? What are you trying to say?

[jasondamour]

@crazy-max thoughts?

[irux]

any updates on this ?

[crazy-max]

Very sorry for the delay!

Changes LGTM but I think we need extra tests as well for this new use case. Can you rebase?

[jasondamour]

Updated from master. @crazy-max I don't really understand the testing framework, can you give some pointers

[crazy-max]

Updated from master.

Can you do a proper rebase instead of merge commit please?

I don't really understand the testing framework, can you give some pointers

In https://github.com/docker/metadata-action/blob/master/__tests__/meta.test.ts to test the case when no image is set. One in this suite

metadata-action/__tests__/meta.test.ts

Line 125 in 879dcbb

describe('push', () => {

would be fine.

[irux]

any news on this ? @crazy-max @jasondamour