- Adds `\livez` for liveness health checking for kube-apiserver. Using the parameter `--maximum-startup-sequence-duration` will allow the liveness endpoint to defer boot-sequence failures for the specified duration period. ([#81969](https://github.com/kubernetes/kubernetes/pull/81969), [@logicalhan](https://github.com/logicalhan))

  * Liveness and readiness probes now support more configuration parameters:
periodSeconds, successThreshold, failureThreshold
  * The new ReplicaSet API (Beta) in the Extensions API group is similar to

    * Bump metadata agent version to 0.2-0.0.21-1.
    * Expand the metadata agent's access to all API groups.
    * Remove metadata agent config maps in favor of command line flags.
    * Update the metadata agent's liveness probe to a new /healthz handler.
    * Logging Agent Improvements
    * Bump logging agent version to 0.2-1.5.33-1-k8s-1.
    * Appropriately set log severity for k8s_container.

- kubelet
  - The deprecated `--experimental-fail-swap-on` flag has been removed ([#69552](https://github.com/kubernetes/kubernetes/pull/69552), [@Pingan2017](https://github.com/Pingan2017))

    * Bump metadata agent version to 0.2-0.0.21-1.
    * Expand the metadata agent's access to all API groups.
    * Remove metadata agent config maps in favor of command line flags.
    * Update the metadata agent's liveness probe to a new /healthz handler.
    * Logging Agent Improvements
    * Bump logging agent version to 0.2-1.5.33-1-k8s-1.
    * Appropriately set log severity for k8s_container.

timeout (if not specified) is `1s` which may be too small for some exec probes. Ensure that pods relying on this behavior are updated to correctly handle probe timeouts. See [configure probe](https://docs.k8s.io/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#configure-probes) section of the documentation for more details.

  - This change in behavior may be unexpected for some clusters and can be disabled by turning off the `ExecProbeTimeout` feature gate. This gate...

* Set route_localnet on nodes & masters in GCE ([#55004](https://github.com/kubernetes/kubernetes/pull/55004), [@ihmccreery](https://github.com/ihmccreery))
* Configurable liveness probe initial delays for etcd and kube-apiserver in GCE ([#57749](https://github.com/kubernetes/kubernetes/pull/57749), [@wojtek-t](https://github.com/wojtek-t))

- Kubeadm: switched the kube-scheduler static Pod to use the endpoints /livez (for startup and liveness probes) and /readyz (for the readiness probe). Previously /healthz was used for all probes, which is deprecated behavior in the scope of this component. ([#126945](https://github.com/kubernetes/kubernetes/pull/126945), [@liangyuanpeng](https://g...

- Limit the body length of exec readiness/liveness probes. remote CRIs and Docker shim read a max of 16MB output of which the exec probe itself inspects 10kb. ([#82514](https://github.com/kubernetes/kubernetes/pull/82514), [@dims](https://github.com/dims))

- Kubeadm: modified the etcd static Pod `liveness` and `readiness` probes to use a new etcd `v3.5.3+` HTTP(s) health check endpoint...