- Added `apiserver_longrunning_requests` metric to replace the soon to be deprecated `apiserver_longrunning_gauge` metric. ([#103799](https://github.com/kubernetes/kubernetes/pull/103799), [@jyz0309](https://github.com/jyz0309))
- Controller-manager: the following flags have no effect and would be removed in v1.24:
  - `--port`

- etcd version monitor metrics are now marked as with the ALPHA stability level. ([#83283](https://github.com/kubernetes/kubernetes/pull/83283), [@RainbowMango](https://github.com/RainbowMango))
- Change `pod_preemption_victims` metric from Gauge to Histogram. ([#83603](https://github.com/kubernetes/kubernetes/pull/83603), [@Tabrizian](https://github.com/Tabrizian))
- Following metrics from kubelet are now marked as with the ALPHA stability level:

- Adds two new metrics to cronjobs, a histogram to track the time difference when a job is created and the expected time when it should be created, as well as a gauge for the missed schedules of a cronjob ([#99341](https://github.com/kubernetes/kubernetes/pull/99341), [@alaypatel07](https://github.com/alaypatel07))

- Client-go now exposes two new metrics to monitor the client-go logic that
  generate http.Transports for the clients.
  
  - `rest_client_transport_cache_entries` is a gauge metric
  with the number of existing entries in the internal cache
  
  - `rest_client_transport_create_calls_total` is a counter
  that increments each time a new transport is created, storing

## Metrics Changes

### Added metrics

* Add aggregator_unavailable_apiservice_{count,gauge} metrics in the kube-aggregator. ([#71380](https://github.com/kubernetes/kubernetes/pull/71380), [@sttts](https://github.com/sttts))

- `apiserver_longrunning_gauge` was removed from the codebase. Please use `apiserver_longrunning_requests`
  instead.
   ([#110310](https://github.com/kubernetes/kubernetes/pull/110310), [@logicalhan](https://github.com/logicalhan))

- Added two client certificate metrics for exec auth:
    - `rest_client_certificate_expiration_seconds` a gauge reporting the lifetime of the current client certificate. Reports the time of expiry in seconds since January 1, 1970 UTC.

### Deprecated/changed metrics

- kubelet probe metrics are now of the counter type rather than the gauge type, and the `prober_probe_result` has been replaced by `prober_probe_total`. ([#76074](https://github.com/kubernetes/kubernetes/pull/76074), [@danielqsj](https://github.com/danielqsj))

### Bug or Regression