📖 Add Go section to install clusterctl

[sivchari]

What this PR does / why we need it:

I added the Go section to install clusterctl via go install.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

/area documentation

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[sivchari]

Ah, sorry. Presumably, we can't embed the some versions via ldflags option if we use go install.
So, this PR might not be necessary. Or, do we need to deal with the way to use go install ?

[chrischdi]

Ah, sorry. Presumably, we can't embed the some versions via ldflags option if we use go install. So, this PR might not be necessary. Or, do we need to deal with the way to use go install ?

An alternative would be to make clusterctl not fail when the ld flags have not been set. Afaik they are only used for the version subcommand (which should be okay) and as post run to check for new versions.

[sivchari]

I think it's prefer the way you propose. So I'd open the issue to discuss about it.

[sbueringer]

Did this work for you?

It didn't for me:

$ go install sigs.k8s.io/cluster-api/cmd/clusterctl@latest
go: downloading sigs.k8s.io/cluster-api v1.9.3

$ ~/code/bin/clusterctl version
clusterctl version: &version.Info{Major:"", Minor:"", GitVersion:"", GitCommit:"", GitTreeState:"", BuildDate:"", GoVersion:"go1.22.1", Compiler:"gc", Platform:"darwin/arm64"}

[sivchari]

Sorry for the late reply.

It didn't for me, too.

Expected

clusterctl version: &version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.3", GitCommit:"cd279dd0c24c5472db45255e3805ae16c61e1432", GitTreeState:"clean", BuildDate:"2024-12-23T13:13:07Z", GoVersion:"go1.22.10", Compiler:"gc", Platform:"darwin/arm64"}

Actual

clusterctl version: &version.Info{Major:"", Minor:"", GitVersion:"", GitCommit:"", GitTreeState:"", BuildDate:"", GoVersion:"devel go1.24-ccf4ebbb61 Wed Dec 4 04:10:56 2024 +0000", Compiler:"gc", Platform:"darwin/arm64"}

But it work when I pass the ldflags like this

go install  -ldflags "-X 'sigs.k8s.io/cluster-api/version.gitMajor=1' -X 'sigs.k8s.io/cluster-api/version.gitMinor=9'" sigs.k8s.io/cluster-api/cmd/clusterctl@latest

clusterctl version: &version.Info{Major:"1", Minor:"9", GitVersion:"", GitCommit:"", GitTreeState:"", BuildDate:"", GoVersion:"devel go1.24-ccf4ebbb61 Wed Dec 4 04:10:56 2024 +0000", Compiler:"gc", Platform:"darwin/arm64"}

Of course, I still didn't get the GitCommit etc.

Should I rewrite this section or remove it ?

[sbueringer]

I'm wondering if there is a way to make the "simple" go install work (including the correct version). Do we know if that works with some other projects and if yes, what they do differently?

[fabriziopandini]

AFAIK both kubectl and kubeadm do not support installing with go install

TBH, I would prefer to not support go install vs supporting it with cryptic -ldflags or knowing it leads to wrong version

[chrischdi]

Note: with go install the debug.ReadBuildInfo() get's populated which contains a .Main.Version.

In case of go build this normally contains (devel), so its useless.

But when using go install [email protected] it contains vx.x.x.
In case of using go isntall module@CommitHash it contains e.g. v0.0.0-20250108155011-73ddd0ddd442.

[chrischdi]

But: I'd prefer to not add this to the documentation as it leads to binaries built differently and we don't have the bandwidth to support this.

@sivchari is there a strong use case over not using the pre-compiled released binaries?

We make sure that the pre-built and released binaries are built with the right go version and these binaries get tested in CI too (for linux amd64).

[sivchari]

Hi @chrischdi
Thank you for good feedback. Honestly, I don't have strong use case. I usually use go install to get the binary. Thus I noticed it, but as @fabriziopandini and you said, I thought that it's better not to have various way to install clusterctl, too.
So I close this PR since I change my mind not to add this document.
Thanks all.

[chrischdi]

Thanks for clarification :-)