Add opencontainers labels for container image

[jkremser]

Although, we don't produce OCI compliant images at the moment. It would be nice to adapt their metadata standards for start. Some tools can already interpret them even if provided as labels in the image json manifest and not as intended (which is OCI annotations).

I was looking into how to produce those OCI images and it's not that easy with goreleaser. It can support podman as enterprise feature, otherwise it uses docker. I was playing with skopeo that can save any image as tar in OCI format. Github registries are ready for OCI images.

There are also org.opencontainers.image.base.name & org.opencontainers.image.base.digest annotations/labels, that can help to construct the full lineage of predecessor of the image (FROM ... relation). These can be added later if we decide that we or community need/want them.

Signed-off-by: Jirka Kremser [email protected]

[ytsarev]

Isn't it something that can be potentially enhanced in operator-sdk build scripts upstream?

[jkremser]

Isn't it something that can be potentially enhanced in operator-sdk build scripts upstream?

right, can be, can be.. Although they don't use the goreleaser, but instead prepare some makefile target with docker command.

Recently there was a long discussion about the makefile on kubebuilder@slack. They want to make it more general so that one can plug any other tool instead of the docker... but this assumes the same api contract.. you know all the params need to be the same. It hasn't been merged yet, but if it is, I would rather not add it, because these labels need to be passed as docker build --label .. or as build-args as I do it here and then interpret them in the Dockerfile.