* Migrate the metrics/v1alpha1 API to metrics/v1beta1.  The HorizontalPodAutoscaler ([#51653](https://github.com/kubernetes/kubernetes/pull/51653), [@DirectXMan12](https://github.com/DirectXMan12))
    * controller REST client now uses that version.  For v1beta1, the API is now known as
    * resource-metrics.metrics.k8s.io.

- Autoscaling/v2beta2 and custom_metrics/v1beta2 have been introduced, which implement metric selectors for Object and Pods metrics, as well as allowing AverageValue targets on Objects, similar to External metrics. ([#64097](https://github.com/kubernetes/kubernetes/pull/64097), [@damemi](https://github.com/damemi)) Courtesy of SIG API Machinery, SIG Architecture, SIG Autoscaling,...

* The Metrics Server now exposes metrics via the /metric endpoint. These metrics are in the prometheus format.  ([#57456](https://github.com/kubernetes/kubernetes/pull/57456), [@kawych](https://github.com/kawych))

- Metrics can now be disabled explicitly via a command line flag (i.e. '--disabled-metrics=metric1,metric2') ([#99217](https://github.com/kubernetes/kubernetes/pull/99217), [@logicalhan](https://github.com/logicalhan))

- HPA controller exposes the following metrics from the kube-controller-manager. 
  - `metric_computation_duration_seconds`: The time(seconds) that the HPA controller takes to calculate one metric.

has been deprecated as part of the deprecation of Heapster. Instead, you may use the [metrics server](https://github.com/kubernetes-incubator/metrics-server). It's a simplified heapster that is able to gather and serve current metrics values. It provides the Metrics API that is used by `kubectl top`, and horizontal pod autoscaler. Note that it doesn't include some features of Heapster, such as short term metrics for graphs in kube-dashboard and dedicated push sinks, which proved hard to maintain and...

- Metrics server nanny has now poll period set to 30s (previously 5 minutes) to allow faster scaling of metrics server. ([#101869](https://github.com/kubernetes/kubernetes/pull/101869), [@olagacek](https://github.com/olagacek)) [SIG Cloud Provider and Instrumentation]

- Adds `apiserver_watch_list_duration_seconds` metrics. Which will measure response latency distribution in seconds for watch list requests broken by group, version, resource and scope ([#120490](https://github.com/kubernetes/kubernetes/pull/120490), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery and Instrumentation]

  - Applications that fetch metrics from kube-scheduler should use a dedicated service account which is allowed to access nonResourceURLs `/metrics`. ([#96345](https://github.com/kubernetes/kubernetes/pull/96345), [@ingvagabund](https://github.com/ingvagabund)) [SIG Cloud Provider, Scheduling and Testing]

- Add one metrics(`kubelet_volume_stats_health_abnormal`) of volume health state to kubelet ([#105585](https://github.com/kubernetes/kubernetes/pull/105585), [@fengzixu](https://github.com/fengzixu))