- kubelet: Users can now enable the alpha NodeLease feature gate to have the Kubelet create and periodically renew a Lease in the kube-node-lease namespace. The lease duration defaults to 40s, and can be configured via the kubelet.config.k8s.io/v1beta1.KubeletConfiguration's NodeLeaseDurationSeconds field. ([#66257](https://github.com/kubernetes/kubernetes/pull/66257), [@mtaufen](https://github.com/mtaufen))...

- 'Promoted the `APIServerIdentity` feature to Beta. By default, each `kube-apiserver`
  will now create a Lease in the `kube-system` namespace. These lease objects can
  be used to identify the number of active API servers in the cluster, and may also
  be used for future features such as the Storage Version API.'

* kube-apiserver: the default `--endpoint-reconciler-type` is now `lease`. The `master-count` endpoint reconciler type is deprecated and will be removed in 1.13. ([#63383](https://github.com/kubernetes/kubernetes/pull/63383), [@liggitt](https://github.com/liggitt))

 - Kubeadm: the flag `--cri-socket` is no longer allowed in a mixture with the flag `--config`. Please use the kubeadm configuration for setting the CRI socket for...

  KEPs or supporting documentation, please reference a specific commit and avoid
  linking directly to the master branch. This ensures that links reference a
  specific point in time, rather than a document that may change over time.
  
  See here for guidance on getting permanent links to files: https://help.github.com/en/articles/getting-permanent-links-to-files
  
  Please use the following format for linking documentation:

    * --alpha-endpoint-reconciler-type=(master-count, lease, none) (default
    * "master-count"). The original reconciler is 'master-count'. The 'lease'
    * reconciler uses the storageapi and a TTL to keep alive an endpoint within the
    * `kube-apiserver-endpoint` storage namespace. The 'none' reconciler is a noop

- The `v1` version of `LeaderMigrationConfiguration` supports only `leases` API for leader election. To use formerly supported mechanisms, please continue using `v1beta1`. ([#108016](https://github.com/kubernetes/kubernetes/pull/108016), [@jiahuif](https://github.com/jiahuif))

  KEPs or supporting documentation, please reference a specific commit and avoid
  linking directly to the master branch. This ensures that links reference a
  specific point in time, rather than a document that may change over time.
  
  See here for guidance on getting permanent links to files: https://help.github.com/en/articles/getting-permanent-links-to-files
  
  Please use the following format for linking documentation:

// https://www.iana.org/domains/root/db/lawyer.html
lawyer

// lds : IRI Domain Management, LLC
// https://www.iana.org/domains/root/db/lds.html
lds

// lease : Binky Moon, LLC
// https://www.iana.org/domains/root/db/lease.html
lease

// leclerc : A.C.D. LEC Association des Centres Distributeurs Edouard Leclerc
// https://www.iana.org/domains/root/db/leclerc.html
leclerc

    try {
      insert(e);
    } finally {
      monitor.leave();
    }
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable E poll() {
    Monitor monitor = this.monitor;
    if (monitor.enterIf(notEmpty)) {
      try {
        return extract();
      } finally {
        monitor.leave();
      }
    } else {
      return null;
    }
  }