- Allow to monitor client-go DNS resolver latencies via `rest_client_dns_resolution_duration_seconds` Prometheus metric. ([#115357](https://github.com/kubernetes/kubernetes/pull/115357), [@mfojtik](https://github.com/mfojtik))

  - By default, injected tokens are given an extended lifetime so they remain valid even after a new refreshed token is provided. The metric `serviceaccount_stale_tokens_total` can be used to monitor for workloads that are depending on the extended lifetime and are continuing to use tokens even after a refreshed token is provided to the container. If that metric indicates no existing workloads are depending on extended lifetimes, injected token...

### Other notable changes

* Fix scheduler cache panic when updating pod conditions. ([#56731](https://github.com/kubernetes/kubernetes/pull/56731), [@bsalamat](https://github.com/bsalamat))
* Add new Prometheus metric that monitors the remaining lifetime of certificates used to authenticate requests to the API server. ([#50387](https://github.com/kubernetes/kubernetes/pull/50387), [@jcbsmpsn](https://github.com/jcbsmpsn))

- Add three metrics to the job controller to monitor if a job works in healthy condition.
  `IndexedJob` has been promoted to Beta. ([#101292](https://github.com/kubernetes/kubernetes/pull/101292), [@AliceZhang2016](https://github.com/AliceZhang2016))

- Added a new metric `webhook_fail_open_count` to monitor webhooks that fail to open. ([#107171](https://github.com/kubernetes/kubernetes/pull/107171), [@ltagliamonte-dd](https://github.com/ltagliamonte-dd))

  * Considering the clusterID field is a required parameter for CSI driver for its operations, but in-tree StorageClass has monitors field as a required parameter, a Kubernetes storage admin has to create a clusterID based on the monitors hash ( ex:#echo -n '<monitors_string>' | md5sum) in the CSI config map and keep the monitors under this clusterID configuration.

- Client-go: Optimized leaders renewing leases by updating leader lock optimistically without getting the record from the API server first. Also, a new metric `leader_election_slowpath_total` was added to allow users to monitor how many leader elections are updated non-optimistically.
   ([#122069](https://github.com/kubernetes/kubernetes/pull/122069), [@linxiulei](https://github.com/linxiulei))

  - go_sched_latencies_seconds ([#111910](https://github.com/kubernetes/kubernetes/pull/111910), [@tosi3k](https://github.com/tosi3k))
- Added new metric `job_controller_terminated_pods_tracking_finalizer` which can be used to monitor whether the job controller is removing Pod finalizers from terminated Pods after accounting them in Job status. ([#113176](https://github.com/kubernetes/kubernetes/pull/113176), [@alculquicondor](https://github.com/alculquicondor))