KCP: expose additional LeaderElection configuration as flags

[rudoi]

Background

The default leader election configuration options are:

• LeaseDuration: 15 seconds
• RenewDeadline: 10 seconds
• RetryPeriod: 2 seconds

These values are quite small, but reasonable for most controllers. However, when the KCP controller is facilitating an upgrade, there is a legitimate risk that API server connectivity is disrupted (see #2652). On a self-managed cluster, because of these small values, this disruption can result in the controller losing track of its leader election. This causes the controller pod to crash.

The Request

We (as self-managed cluster users) would like to be able to configure these parameters. Flags seem reasonable!

/kind feature
/cc @vincepri @mytunguyen @sethp-nr

[rudoi]

/assign
/lifecycle active

[rudoi]

just waiting for #2656 and then i'll get going on this

[rudoi]

/assign @trutx

[k8s-ci-robot]

@rudoi: GitHub didn't allow me to assign the following users: trutx.

Note that only kubernetes-sigs members, repo collaborators and people who have commented on this issue/PR can be assigned. Additionally, issues/PRs can only have 10 assignees at the same time.
For more information please see the contributor guide

In response to this:

/assign @trutx

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.

[trutx]

I can pick this up if you don't mind

[rudoi]

let's try this again!

/assign @trutx