Add a version command or option to controller-gen

[alexkreidler]

It would be great to know which version of controller-gen we're using in our kubebuilder projects to better diagnose errors and help the community.

Please add a version command or --version or -v flags to controller-gen to help us with this. Thanks a ton!

[jiachengxu]

Yes, this would be helpful, since I encountered a similar issue with kubebuilder :kubernetes-sigs/kubebuilder#909. I could try to work on this if help is needed.

[DirectXMan12]

/kind feature
/help-wanted

You can more-or-less copy the ldflags/git approach from other projects or bits of kubernetes. If you've done something similar before, or are willing to do a bit of bash/makefile spelunking, this is a reasonable starter issue.

[DirectXMan12]

/priority backlog

[DirectXMan12]

/help

[k8s-ci-robot]

@DirectXMan12:
This request has been marked as needing help from a contributor.

Please ensure the request meets the requirements listed here.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-help command.

In response to this:

/help

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[DirectXMan12]

(we'd probably add this as a --version flag)

[jiachengxu]

Hi @DirectXMan12, if help is needed, I am willing to work on this issue, any more hints on this?

[DirectXMan12]

kustomize uses goreleaser, so it's not 1-to-1, but you can get the gist of the general technique here: https://github.com/kubernetes-sigs/kustomize/blob/master/releasing/goreleaser.yaml#L11 / https://github.com/kubernetes-sigs/kustomize/blob/master/pkg/commands/misc/version.go

Instead of goreleaser, we'd use a script to grab the version info. The general trick is to run something like git describe --tags --abbrev=14 and pull the version and commit out of that.
metrics-server uses a giant makefile for doing it, but has extra fancy footwork to stay compatible with what's done in kubernetes/kubernetes: https://github.com/kubernetes-incubator/metrics-server/blob/master/hack/Makefile.buildinfo. I don't think we need to get that complicated, though.

On further thought, since we're generally go-installing, we probably need to make use of https://golang.org/pkg/runtime/debug/#BuildInfo to grab the version info at runtime. Then we can print that out.

[dlespiau]

/assign @dlespiau