Add v prefixed release tags

[jpreese]

When consuming modules from Go, the Go toolchain expects tags to start with v.

Going forward, could a tag be added that contains the v prefix? It would be nice to add some retroactively as well. Thanks!

[howardjohn]

Is v a hard requirement, I thought it supported both forms?

[jpreese]

It is a hard requirement. If the module that you're referencing does not have tags prefixed with v, it won't resolve correctly and some manual intervention is required.

[howardjohn]

Thanks, I didn't realize that. I think we have some code that expects to not have a v prefix, so we would need to have double tags probably.. or more precisely we have code that looks at the version string in the code. I supposed we could tag with v but set the version without v.

We do not follow proper semver though, so fixing this may cause some problems there as well

fyi @jasonwzm probably even more relevant for client-go

[jpreese]

client-go is also relevant. If you're trying to keep them in sync, double tagging may also help as client-go currently will keep grabbing the latest Istio API (references istio.io/api v0.0.0-20191109011911-e51134872853)

[howardjohn]

We would need to do more than double tagging for that right? eg if we release 1.5.1, we tag both repos v1.5.1, but then we need to update go.mod in client-go to point to istio.io/api@v1.5.1?

[jpreese]

That is correct, yes.

Right now I'm using client-go (which requires istio.io/api), but in my go.mod they have different dates on them. It hasn't caused any problems that I'm aware of, but just a thought if the goal is to keep them in sync.

my go.mod

...
	istio.io/api v0.0.0-20191205234547-d2b87eef5659
	istio.io/client-go v0.0.0-20191206191348-5c576a7ecef0

[jasonwzm]

For client-go which is user-facing, we can tag the repo with v versions. We can follow something here: https://github.com/kubernetes/client-go/blob/master/INSTALL.md#add-client-go-as-a-dependency

But for Istio internal usage of different go modules, we currently use sha to import a repo, which is intended. For pseudo versions in go modules, the difference in timestamps are fine as long as they are using the correct sha for each repo.

@howardjohn can you help adding double tagging for client-go in the next release? I could not find the release checklist doc.

[howardjohn]

@jasonwzm its all automated in istio/release-builder. Under publish/github there should be stuff about tagging