* This PR will leverage subtests on the existing table tests for the scheduler units. ([#63658](https://github.com/kubernetes/kubernetes/pull/63658), [@xchapter7x](https://github.com/xchapter7x))
    * Some refactoring of error/status messages and functions to align with new approach.
* kubeadm upgrade now supports external etcd setups again ([#63495](https://github.com/kubernetes/kubernetes/pull/63495), [@detiber](https://github.com/detiber))

- JSON log output is configurable and now supports writing info messages to stdout and error messages to stderr. Info messages can be buffered in memory. The default is to write both to stdout without buffering, as before. ([#104873](https://github.com/kubernetes/kubernetes/pull/104873), [@pohly](https://github.com/pohly))

- Modified log messages that were logged with `"v":0` in JSON output although they were debug messages with a higher verbosity. ([#106978](https://github.com/kubernetes/kubernetes/pull/106978), [@p...

- Fixes the flooding warning messages about setting volume ownership for configmap/secret volumes ([#92878](https://github.com/kubernetes/kubernetes/pull/92878), [@jvanz](https://github.com/jvanz)) [SIG Instrumentation, Node and Storage]

- Migrate some log messages to structured logging in `pkg/volume/plugins.go`. ([#101510](https://github.com/kubernetes/kubernetes/pull/101510), [@huchengze](https://github.com/huchengze))

### Structured logging

SIG Instrumentation standardized the structure of log messages and references to Kubernetes objects. Structured logging makes parsing, processing, storing, querying and analyzing logs easier. New methods in the klog library enforce log message structure.

- When using `kubectl logs <pod-name>` and the pod is not found, the error message now includes the namespace. Previously, the message would be "Error from server (NotFound): pods "my-pod-name" not found". Now, it reflects the namespace in the message as follows: "Error from server (NotFound): pods "my-pod-name" not found in namespace "default"".

* The alpha `metadata.initializers` field, deprecated in 1.13, has been removed. ([#79504](https://github.com/kubernetes/kubernetes/pull/79504), [@yue9944882](https://github.com/yue9944882))
* Fix duplicate error messages in cli commands ([#79493](https://github.com/kubernetes/kubernetes/pull/79493), [@odinuge](https://github.com/odinuge))

- Improved `kubectl run` and `kubectl debug` error messages upon attaching failures. ([#110764](https://github.com/kubernetes/kubernetes/pull/110764), [@soltysh](https://github.com/soltysh))

  logs to populate the termination message if the user does not write to the
  termination message log file. The termination message file is now properly
  readable for end users and has a maximum size (4k bytes) to prevent abuse.
  Each pod may have up to 12k bytes of termination messages before the contents
  of each will be truncated.