- The `PersistentVolumeLabel` admission controller will be removed in a future release, when the out-of-tree versions of the GCE and AWS cloud providers move to GA. The cloud providers are marked alpha in version 1.9.

### OpenStack

- the IP allocator in v1.17.0 can return errors such as `the cluster IP <ip> for service <service-name> is not within the service CIDR <cidr>; please recreate` in the logs of the kube-apiserver. The cause is incorrect CIDR calculations if the service CIDR (`--service-cluster-ip-range`) is set to bits...

To learn more about the feature, please refer to the official [seccomp tutorial](https://kubernetes.io/docs/tutorials/clusters/seccomp/#enable-the-use-of-runtimedefault-as-the-default-seccomp-profile-for-all-workloads).

### Quality of Service for memory resources

- Promoted CRI communication of the cgroup driver mechanism to beta. The `KubeletCgroupDriverFromCRI` feature gate is now in beta and enabled by default. This allows the kubelet to query the container runtime using CRI to determine the mechanism for cgroup management. If the container runtime doesn't support this, the kubelet falls back to using the configuration file (you can also use the deprecated `--cgroup-driver` command line argument). ([#125828](https...

  // ConfigMap will be projected into the volume as a file whose name is the
  // key and content is the value. If specified, the listed keys will be
  // projected into the specified paths, and unlisted keys will not be
  // present. If a key is specified which is not present in the ConfigMap,
  // the volume setup will error unless it is marked optional. Paths must be

* The kube-apiserver discovery APIs (for example, `/apis`) return information about the API groups being served, and can change dynamically.
During server startup, prior to the server reporting healthy (via `/healthz`), not all API groups may be reported.
Wait for the server to report healthy (via `/healthz`) before depending on the information provided by the discovery APIs.

Rescheduler 0.3 shipped together with Kubernetes 1.6 understands the new taints and will clean up the old annotations, but Rescheduler 0.2 shipped together with Kubernetes 1.5 doesn't understand the new taints. In order to avoid eviction loop during 1.5->1.6 upgrade you need to either upgrade the master node atomically (for example by using `upgrade.sh` script for GCE) or ensure that the rescheduler is upgraded first, then the scheduler and then all the other master components.

* **Tolerations**...

- When using `kubectl replace` (or the equivalent API call) on a Service, the caller no longer needs to do a read-modify-write cycle to fetch the allocated values for `.spec.clusterIP` and `.spec.ports[].nodePort`.  Instead the API server will automatically carry these forward from the original object when the new object does not specify them. ([#104674](https://github.com/kubernetes/kubernetes/pull/104674), [@thockin](https://github.com/thockin))...

e2e tests that require SSH may now be used against clusters that have nodes without external IP addresses by setting the environment variable `KUBE_SSH_BASTION` to the `host:port` of a machine that is allowed to SSH to those nodes.  The same private key that the test would use is used for the bastion host.  The test connects to the bastion and then tunnels another SSH connection to the node. ([#72286](https://github.com/kubernetes/kubernetes/pull/72286), [@smarterclayton](https://github.com/smarterclayton))...

*   The admission webhook configurations API, part of the admissionregistration API, is now at v1beta1. Delete any existing webhook configurations before you upgrade, and update your configuration files to use the latest API. For this and the previous change, see also [the documentation](https://kubernetes.io/docs/admin/extensible-admission-controllers/#external-admission-webhooks).