- Kubeadm: added the experimental (alpha) feature gate `EtcdLearnerMode` that allows etcd members to be joined as learner and only then promoted as voting members ([#113318](https://github.com/kubernetes/kubernetes/pull/113318), [@pacoxu](https://github.com/pacoxu))

- [`KT-54452`](https://youtrack.jetbrains.com/issue/KT-54452) Kotlin/JS libraries with "joined" legacy+IR content: publish IR sources for them

assignment of regular parameters.
</p>

<pre>
func Split(s string, pos int) (string, string) {
	return s[0:pos], s[pos:]
}

func Join(s, t string) string {
	return s + t
}

if Join(Split(value, len(value)/2)) != value {
	log.Panic("test fails")
}
</pre>

<p>
A method call <code>x.m()</code> is valid if the <a href="#Method_sets">method set</a>

Features for this release were tracked via the use of the [kubernetes/features](https://github.com/kubernetes/features) issues repo. Each Feature issue is owned by a Special Interest Group from [kubernetes/community](https://github.com/kubernetes/community)

## Kubefed

- kubeadm: Improved resiliency when it comes to updating the `kubeadm-config` configmap upon new control plane joins or resets. This allows for safe multiple control plane joins and/or resets. ([#76821](https://github.com/kubernetes/kubernetes/pull/76821), [@ereslibre](https://github.com/ereslibre))

  // Some volume types allow the Kubelet to change the ownership of that volume
  // to be owned by the pod:
  //
  // 1. The owning GID will be the FSGroup
  // 2. The setgid bit is set (new files created in the volume will be owned by FSGroup)
  // 3. The permission bits are OR'd with rw-rw----
  //

### Juju
* The kubernetes-master, kubernetes-worker and kubeapi-load-balancer charms have gained an nrpe-external-master relation, allowing the integration of their monitoring in an external Nagios server. ([#41923](https://github.com/kubernetes/kubernetes/pull/41923), [@Cynerva](https://github.com/Cynerva))

* `--feature-gates` argument has been removed from the `kubeadm join` command. Feature gates will be retrieved from the cluster configuration during the join process. ([#70755](https://github.com/kubernetes/kubernetes/pull/70755), [@ereslibre](https://github.com/ereslibre))

- Kubeadm: during join when a check is performed that a Node with the same name already exists in the cluster, make sure the NodeReady condition is properly validated ([#89602](https://github.com/kubernetes/kubernetes/pull/89602), [@kvaps](https://github.com/kvaps)) [SIG Cluster Lifecycle]

### Instrumentation

In v1.9 we focused on improving stability of the components owned by the SIG, including Heapster, Custom Metrics API adapters for Prometheus, and Stackdriver.

### Network