Add OCI annotations to docker images

[mikaello]

It would have been nice if the Kroki docker image built in this project used the OCI annotations, these can be used by other tools to enhance the user experience. E.g. Renovate will use the source label to add a link back to where the image is coming from.

Currently, there are no labels for the kroki image:

$ docker inspect yuzutech/kroki:0.20.0 --format '{{ json .Config.Labels }}'
null

This could be done be adding the OCI labels directly into the Dockerfile, or by using the docker/metadata-action, but that is maybe difficult since you are building the images inside a Makefile?

[ggrossetie]

Behind the scene we are using docker buildx bake which supports labels: https://docs.docker.com/build/bake/reference/#targetlabels

It would be useful if you could suggest a list of labels (key and value) that we should set.

[mikaello]

Sure!

The one I find most useful is org.opencontainers.image.source, which can be used to provide a reference back to this repository. But it could be nice some of the others as well:

LABEL \
    org.opencontainers.image.title="Kroki" \
    org.opencontainers.image.description="Kroki provides a unified API supporting multiple diagramming formats, making it easy to create diagrams from textual descriptions." \
    org.opencontainers.image.url="https://kroki.io" \
    org.opencontainers.image.source="https://github.com/yuzutech/kroki" \
    org.opencontainers.image.licenses="MIT"

But you maybe want to use the labels map field in docker-bake.hcl?

[ggrossetie]

Thanks!

But you maybe want to use the labels map field in docker-bake.hcl?

Is there a best practice or a recommended way to define labels?
Since the values are "static" (i.e., do not depend on the context/release) I would say it's fine to define them in the Dockerfile.

Are you willing to submit a pull request?

[mikaello]

Is there a best practice or a recommended way to define labels?

I'm not sure, the docker bake file was new to me, I am only used to pure Dockerfiles.

Are you willing to submit a pull request?

Absolutely :-) #1545