Make RunOrDie start leader election loop in the background or document that it blocks

[ChrsMark]

Hi, I was wondering if there is any particular reason of RunOrDie being a blocking function. I see that it blocks at

client-go/tools/leaderelection/leaderelection.go

Line 222 in 3623386

le.Run(ctx)

since LeaderElector will block in the leader election loop.

I found that k8s autoscaler leverage this blocking thing at https://github.com/kubernetes/autoscaler/blob/a63c7abbe47773be4eec49b13210a3cd9c4a719f/cluster-autoscaler/main.go#L421 and maybe changing this functionality may be a bad idea however how about introducing a sibling of RunOrDie called RunOrDieAsync which will be non-blocking? Otherwise I think the blocking fact should be documented to avoid confusion in the future by people using this library. Happy to provide a PR in any case.

[liggitt]

Documenting the behavior is a good idea, PR is welcome. A separate method isn't needed since callers can do go RunOrDie if they want async behavior. The PR would need to be made to the https://github.com/kubernetes/kubernetes/ repo which is the canonical location for this code.