feat(build-push-to-dockerhub): add labels input

[martincostello]

Allow custom labels to be added to container images.

[Copilot]

Pull Request Overview

This PR adds support for custom labels to the build-push-to-dockerhub composite action. Users can now pass custom labels that will be applied to Docker images during the build process.

• Added a new labels input parameter to the action
• Integrated the labels input with the docker/metadata-action step
• Updated documentation to reflect the new parameter

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
actions/build-push-to-dockerhub/action.yaml	Added labels input definition and passed it to the metadata-action step
actions/build-push-to-dockerhub/README.md	Added documentation for the new labels parameter in the inputs table

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[zerok]

Hey 🙂 IIRC this will soon be deprecated in favor of https://github.com/grafana/shared-workflows/tree/main/actions/docker-build-push-image . Would that action work for your use-case?

[martincostello]

I haven't investigated migrating fully yet, but we only need pushing to Docker Hub and haven't investigated/tested other CPU architectures for the image yet. For now this is just to allow us to resolve grafana/docker-otel-lgtm#837.

[zerok]

Okidoki 🙂 Since both fields have the same name, I think it would be fine to still have that in the "old" action 😄