`v1beta1.KubeletConfiguration`. The new patch target is called `kubeletconfiguration` (e.g. patch file `kubeletconfiguration+json.json`).This makes it possible to apply node specific KubeletConfiguration options during `init`, `join` and `upgrade`, while the main `KubeletConfiguration` that is passed to `init` as part of the `--config` file can still act as the global stored in the cluster `KubeletConfiguration`. ([#110405](https://github.com/kubernetes/kubernetes/pull/110405), [@neolit123](https://github.com/neolit123))...

  // Default is false.
  // Note that this field cannot be set when spec.os.name is windows.
  // +optional
  optional bool readOnlyRootFilesystem = 6;

  // AllowPrivilegeEscalation controls whether a process can gain more
  // privileges than its parent process. This bool directly controls if
  // the no_new_privs flag will be set on the container process.
  // AllowPrivilegeEscalation is true always when the container is:

    * faster handoff when a leader-elected process is gracefully terminated.
* Make volume binder resilient to races between main schedule loop and async binding operation  ([#72045](https://github.com/kubernetes/kubernetes/pull/72045), [@cofyc](https://github.com/cofyc))

Kubernetes 1.15 consists of **25 enhancements**: 2 moving to stable, 13 in beta, and 10 in alpha. The main themes of this release are:

#### Continuous Improvement

            defaultMap.put(FessConfig.TIME_ADJUST_TIME_MILLIS, "0");
            defaultMap.put(FessConfig.MAIL_SEND_MOCK, "true");
            defaultMap.put(FessConfig.MAIL_SMTP_SERVER_MAIN_HOST_AND_PORT, "localhost:25");
            defaultMap.put(FessConfig.MAIL_SUBJECT_TEST_PREFIX, "[Test]");
            defaultMap.put(FessConfig.MAIL_RETURN_PATH, "root@localhost");
            return defaultMap;

### Etcd v3.5.[0-2] data corruption

Data corruption issue was found in etcd v3.5.0 release that was shipped with 1.22 Kubernetes release. Please read up-to-date [production recommendations for etcd](https://github.com/etcd-io/etcd/tree/main/CHANGELOG).

## Urgent Upgrade Notes 

### (No, really, you MUST read this before you upgrade)