Superfluous error logs when only ImpersonationProxy strategy is available

[peterbuecker-form3]

Is your feature request related to a problem? Please describe.

When running Pinniped Concierge in a managed Kubernetes cluster like EKS, it regularly logs error messages stating that it can't find any kube-controller-manager pods, although it has been configured to always run in ImpersonationProxy mode:

{"level":"error","timestamp":"2023-01-17T15:20:13.935196Z","caller":"go.pinniped.dev/internal/controllerlib/controller.go:219$controllerlib.(*controller).handleKey","message":"kube-cert-agent-controller: { } failed with: could not find a healthy kube-controller-manager pod (0 candidates)\n"}

The CredentialIssuer in use:

apiVersion: config.concierge.pinniped.dev/v1alpha1
kind: CredentialIssuer
metadata:
  labels:
    app: pinniped-concierge
  name: pinniped-concierge-config
spec:
  impersonationProxy:
    mode: enabled
    service:
      annotations:
        service.beta.kubernetes.io/aws-load-balancer-connection-idle-timeout: "4000"
      type: LoadBalancer
status:
  strategies:
    - lastUpdateTime: "2023-01-16T09:13:21Z"
      message: could not find a healthy kube-controller-manager pod (0 candidates)
      reason: CouldNotFetchKey
      status: Error
      type: KubeClusterSigningCertificate
    - frontend:
        impersonationProxyInfo:
          certificateAuthorityData: LS0tLS1CRUdJTiB...
          endpoint: https://...
        type: ImpersonationProxy
      lastUpdateTime: "2023-01-16T09:13:27Z"
      message: impersonation proxy is ready to accept client connections
      reason: Listening
      status: Success
      type: ImpersonationProxy

Describe the solution you'd like

When ImpersonationProxy has been selected, and it's working correctly, I don't expect to see any error logs from Concierge relating to KubeClusterSigningCertificate mode.

Describe alternatives you've considered

Alternatively, the log level of these messages could be reduced from error to debug.

Are you considering submitting a PR for this feature?

Yes, I'd be happy to send a PR for this if you find it a reasonable improvement and it seems like a relatively simple change to do for a newcomer to this project.

Additional context

None.

[cfryanr]

Thanks for opening this issue, @peterbuecker-form3!

I'm not sure when we'll have a chance to look into this, but please feel free to consider submitting a PR if you're interested. If you'd like to try a PR, happy to discuss possible solutions in more detail.