Kube-state-metrics: Implement a readiness endpoint

[mrueg]

Is this a BUG REPORT or FEATURE REQUEST?:

Uncomment only one, leave it on its own line:

/kind bug

/kind feature

What happened:
Currently there is a healthz endpoint which implements somewhat liveness but is used as a readinessProbe in the kubernetes deployment files.
What you expected to happen:
A possible option would be to use the healthz endpoint as a path for livenessProbe and have a readyz endpoint for readiness checks.
Probably the readiness probe should return 200 if there is a connection to the cluster possible and should fail otherwise (not sure if the app becomes unhealthy otherwise or would just fail)

[brancz]

I think an initial probe to reach the API and then setting readiness would reasonable.

[Pothulapati]

I'm willing to take this issue, If its available :)

[tariq1890]

Yes please :)!