Citadel CSR signing service,
by periodically sending CSRs to the API. More health checking features are coming shortly.</p><p>Citadel contains a <em>prober client</em> module that periodically checks Citadel's status (currently only the health
status of the gRPC server).
If Citadel is healthy, the <em>prober client</em> updates the <em>modification time</em> of the <em>health status file</em>
(the file is always empty). Otherwise, it does nothing. Citadel relies on a
<a href=https://kubernetes.io/docs/tasks