### Other (Cleanup or Flake)

- Service session affinity timeout tests are no longer required for Kubernetes network plugin conformance due to variations in existing implementations. New conformance tests will be developed to better express conformance in future releases. ([#112806](https://github.com/kubernetes/kubernetes/pull/112806), [@dcbw](https://github.com/dcbw)) [SIG Architecture, Network and Testing]

## Dependencies

### Added

- Graduating `pending_pods`, `preemption_attempts_total`, `preemption_victims` and `schedule_attempts_total` metrics to stable. Also `e2e_scheduling_duration_seconds` is renamed to `scheduling_attempt_duration_seconds` and the latter is graduated to stable. ([#105941](https://github.com/kubernetes/kubernetes/pull/105941), [@rezakrimi](https://github.com/rezakrimi)) [SIG Instrumentation, Scheduling and Testing]

## Changelog since v1.19.2

## Changes by Kind

### Feature

- Kubernetes is now built using go1.15.2
  - build: Update to k/repo-infra@v0.1.1 (supports go1.15.2)
  - build: Use go-runner:buster-v2.0.1 (built using go1.15.1)
  - bazel: Replace --features with Starlark build settings flag
  - hack/lib/util.sh: some bash cleanups
    
    - switched one spot to use kube::logging

### Other (Cleanup or Flake)

- Service session affinity timeout tests are no longer required for Kubernetes network plugin conformance due to variations in existing implementations. New conformance tests will be developed to better express conformance in future releases. ([#112806](https://github.com/kubernetes/kubernetes/pull/112806), [@dcbw](https://github.com/dcbw)) [SIG Architecture, Network and Testing]

## Dependencies

### Added

- kubeadm: Added better handling of errors during unmount when calling `kubeadm reset`. When failing to unmount directories under `/var/run/kubelet`, kubeadm will now throw an error instead of showing a warning and continuing to clean up said directory. In such situations, it is better for you to inspect the problem and resolve it manually. Then, you can call `kubeadm reset` again to complete the cleanup....

- We’re working to simplify the Windows node join experience with better scripts and kubeadm. Scripts and doc updates are still in the works, but some of the needed improvements are included in 1.15.  These include:

* Change docker metrics to conform metrics guidelines and using histogram for better aggregation. ([#72323](https://github.com/kubernetes/kubernetes/pull/72323), [@danielqsj](https://github.com/danielqsj))
    * The following metrics are deprecated, and will be removed in a future release:

  you want to set the equivalent of any of the `--iptables-xxx` options.)
  
  As this code is still very new, it has not been heavily optimized yet;
  while it is expected to _eventually_ have better performance than the
  iptables backend, very little performance testing has been done so far. ([#121046](https://github.com/kubernetes/kubernetes/pull/121046), [@danwinship](https://github.com/danwinship))

- Service session affinity timeout tests are no longer required for Kubernetes network plugin conformance due to variations in existing implementations. New conformance tests will be developed to better express conformance in future releases. ([#112806](https://github.com/kubernetes/kubernetes/pull/112806), [@dcbw](https://github.com/dcbw)) [SIG Architecture, Network and Testing]

  * Fix the Kubelet PLEG update timestamp to better reflect the health of the component when the container runtime request hangs. ([#45496](https://github.com/kubernetes/kubernetes/pull/45496), [@andyxning](https://github.com/andyxning))