pkg time, const ANSIC ideal-string
pkg time, const April Month
pkg time, const August Month
pkg time, const December Month
pkg time, const February Month
pkg time, const Friday Weekday
pkg time, const Hour Duration
pkg time, const January Month
pkg time, const July Month
pkg time, const June Month
pkg time, const Kitchen ideal-string
pkg time, const March Month
pkg time, const May Month

- 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))

    * Add ABRT support. ([#105](https://github.com/kubernetes/node-problem-detector/pull/105), [@juliusmilan](https://github.com/juliusmilan))

    * Add a docker image corruption problem detection in the default docker monitor config. ([#117](https://github.com/kubernetes/node-problem-detector/pull/117), [@ajitak](https://github.com/ajitak))

  * Upgrade CAdvisor to v0.26.1. New features added:

    * Add Docker overlay2 storage driver support.

* Increase waiting time (120s) for docker startup in health-monitor.sh ([#54099](https://github.com/kubernetes/kubernetes/pull/54099), [@dchen1107](https://github.com/dchen1107))

  - 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...

- If BoundServiceAccountTokenVolume is enabled, cluster admins can use metric `serviceaccount_stale_tokens_total` to monitor workloads that are depending on the extended tokens. If there are no such workloads, turn off extended tokens by starting `kube-apiserver` with flag `--service-account-extend-token-expiration=false` ([#96273](https://github.com/kubernetes/kubernetes/pull/96273),...

* kubeadm: use kubeconfig flag instead of kubeconfig-dir on init phase bootstrap-token ([#71803](https://github.com/kubernetes/kubernetes/pull/71803), [@yagonobre](https://github.com/yagonobre))
* On GCI, NPD starts to monitor kubelet, docker, containerd crashlooping, read-only filesystem and corrupt docker overlay2 issues. ([#71522](https://github.com/kubernetes/kubernetes/pull/71522), [@wangzhen127](https://github.com/wangzhen127))

  - 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))

- 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))

 - reach GA, and deprecate the beta, or
 - have a new beta version _(and deprecate the previous beta)_.

If a REST API reaches the end of that nine-month countdown, then the next Kubernetes release will deprecate that API version. More information can be found on [the Kubernetes Blog](https://kubernetes.io/blog/2020/08/21/moving-forward-from-beta/).