### CronJob
* Add configurable limits to CronJob resource to specify how many successful and failed jobs are preserved. ([#40932](https://github.com/kubernetes/kubernetes/pull/40932), [@peay](https://github.com/peay))

### DaemonSet

  A secondary benefit of defending all users' freedom is that
improvements made in alternate versions of the program, if they
receive widespread use, become available for other developers to
incorporate.  Many developers of free software are heartened and
encouraged by the resulting cooperation.  However, in the case of
software used on network servers, this result may fail to come about.

- DRA: When the prioritized list feature was used in a request and the resulting number of allocated devices exceeded the number of allowed devices per claim, the scheduler aborted the attempt to allocate devices early. Previously, it tried to many different combinations, which could take a long time. ([#130593](https://github.com/kubernetes/kubernetes/pull/130593), [@mortent](https://github.com/mortent)) [SIG Apps, Node, Scheduling and Testing]

### Windows

We are advancing support for Windows Server and Windows Server Containers to beta along with continued feature and functional advancements on both the Kubernetes and Windows platforms. This opens the door for many Windows-specific applications and workloads to run on Kubernetes, significantly expanding the implementation scenarios and the enterprise reach of Kubernetes.

## Before Upgrading

- Reduce API server memory when many CRDs are loaded by sharing a single etcd3 client logger across all clients ([#111648](https://github.com/kubernetes/kubernetes/pull/111648), [@negz](https://github.com/negz)) [SIG API Machinery]

### Immutable Secrets and ConfigMaps (beta)

Secret and ConfigMap volumes can be marked as immutable, which significantly reduces load on the API server if there are many Secret and ConfigMap volumes in the cluster.
See [ConfigMap](https://kubernetes.io/docs/concepts/configuration/configmap/) and [Secret](https://kubernetes.io/docs/concepts/configuration/secret/) for more information.

- Using exec auth plugins with kubectl no longer results in warnings about constructing many client instances from the same exec auth config. ([#97857](https://github.com/kubernetes/kubernetes/pull/97857), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Auth]

* Do not detach volume if mount in progress ([#71145](https://github.com/kubernetes/kubernetes/pull/71145), [@gnufied](https://github.com/gnufied))
* Improve efficiency of preemption logic in clusters with many pending pods. ([#72895](https://github.com/kubernetes/kubernetes/pull/72895), [@bsalamat](https://github.com/bsalamat))

By default, the `fsgroup` setting, if specified, recursively updates permissions for every file in a volume on every mount. This can make mount, and pod startup, very slow if the volume has many files. 

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
- Project sustainability is not just about features. Many SIGs have been working on  improving test coverage, ensuring the basics stay reliable, and stability of the core feature set and working on maturing existing features and cleaning up the backlog.

#### Extensibility