Replace custom tag logic with docker/metadata-action

[felddy]

🚀 Feature Proposal

See:

• https://github.com/docker/metadata-action
• https://github.com/actions/starter-workflows/blob/main/ci/docker-publish.yml

Motivation

There is an action that looks like it can cleanly handle a lot of the custom logic in our build workflow.
There might be a bit of tweaking to deal with :latest in the way we treat it.

Example

See:

• https://github.com/actions/starter-workflows/blob/main/ci/docker-publish.yml

Pitch

Because less is more.

[felddy]

Current issue in testing.

:latest and :release tags are not being enabled when a semver release is created from the default branch. Note that the other semver tags were emitted.

foundryvtt-docker/.github/workflows/build.yml

Lines 157 to 169 in 512024a

	tags: |
	type=edge
	type=raw,event=workflow_dispatch,value=${{ github.event.inputs.dispatch-tag}}
	type=ref,event=branch
	type=ref,event=pr
	type=schedule,pattern=nightly
	type=semver,pattern=latest,enable={{is_default_branch}}
	type=semver,pattern=release,enable={{is_default_branch}}
	type=semver,pattern=prerelease,enable=${{ github.ref == format('refs/heads/{0}', 'prerelease') }}
	type=semver,pattern={{version}}
	type=semver,pattern={{major}}.{{minor}}
	type=semver,pattern={{major}}
	type=sha

https://github.com/felddy/ci-testing/runs/6711605353?check_suite_focus=true#step:6:71

2022-06-02T15:47:51.5546431Z felddy/ci-testing:1.2.3
2022-06-02T15:47:51.5546702Z felddy/ci-testing:1.2
2022-06-02T15:47:51.5546964Z felddy/ci-testing:1
2022-06-02T15:47:51.5547246Z felddy/ci-testing:sha-3d0b305
2022-06-02T15:47:51.5547547Z ghcr.io/felddy/ci-testing:1.2.3
2022-06-02T15:47:51.5548084Z ghcr.io/felddy/ci-testing:1.2
2022-06-02T15:47:51.5548365Z ghcr.io/felddy/ci-testing:1
2022-06-02T15:47:51.5548678Z ghcr.io/felddy/ci-testing:sha-3d0b305

[felddy]

It looks like github.ref is refs/tags/v1.2.3, which explains why the {{is_default_branch}} is failing.

See:

• https://github.com/docker/metadata-action/blob/69f6fc9d46f2f8bf0d5491e4aabe0bb8c6a4678a/src/meta.ts#L383-L392
• is_default_branch global expression docker/metadata-action#192

Probably should try {{base_ref}}

[felddy]

This feature was added during the refactor of workflows:
See:

• Improvement: reusable workflows #369