* Protobuf serialization does not distinguish between `[]` and `null`.
API fields previously capable of storing and returning either `[]` and `null` via JSON API requests (for example, the Endpoints `subsets` field)

    * ServiceDelimiter string Delimiter to use to separate overridden services (multiple services) Defaults to "&"
    * ServicenameDelimiter string Delimiter to use to separate servicename from its configuration parameters Defaults "|"
    * OverrideSeparator string Delimiter to use to separate region of occurrence, url and signing region for each override Defaults to ","

- Fix an error when using external etcd but storing etcd certificates in the same folder with the same name used by kubeadm for local etcd certificates; for an older version of kubeadm, the workaround is to avoid file name used by kubeadm for local etcd. ([#80867](https://github.com/kubernetes/kub...

* `kubectl patch` now supports `--dry-run`. ([#60675](https://github.com/kubernetes/kubernetes/pull/60675), [@timoreimann](https://github.com/timoreimann))
* fix sorting taints in case the sorting keys are equal ([#61255](https://github.com/kubernetes/kubernetes/pull/61255), [@dixudx](https://github.com/dixudx))

  with the number of existing entries in the internal cache
  
  - `rest_client_transport_create_calls_total` is a counter
  that increments each time a new transport is created, storing
  the result of the operation needed to generate it: hit, miss
  or uncacheable. ([#117295](https://github.com/kubernetes/kubernetes/pull/117295), [@aojea](https://github.com/aojea))

  
  The API does include a few breaking changes:
  - The "extraArgs" component construct is now a list of "name"/"value" pairs instead of a string/string map. This has been done to support duplicate args where needed.
  - The "JoinConfiguration.discovery.timeout" field has been replaced by "JoinConfiguration.timeouts.discovery".

*   The Kubelet's feature gates are now specified as a map when provided via a JSON or YAML KubeletConfiguration, rather than as a string of key-value pairs, making them less awkward for users. ([#53025](https://github.com/kubernete...

  * OOM parser uses kmsg
  * Add hugepages support
  * Add CRI-O support

* Sharing a PID namespace between containers in a pod is disabled by default in version 1.8. To enable for a node, use the `--docker-disable-shared-pid=false` kubelet flag. Be aware that PID namespace sharing requires Docker version greater than or equal to 1.13.1.

* Fix issues related to the eviction manager.

- Empty values are no longer assigned to undefined resources (CPU or memory) when storing the resources allocated to the pod in checkpoint. ([#117615](https://github.com/kubernetes/kubernetes/pull/117615), [@aheng-ch](https://github.com/aheng-ch))
- Fixed CEL estimated cost of `replace()` to handle a zero length replacement string correctly.

- Changes the kubectl --validate flag from a bool to a string that accepts the values {true, strict, warn, false,...