1.6 will also default to protobuf encoding if using etcd3.  **This change is
irreversible.**  To rollback, you must restore from a backup made before the
protobuf/etcd3 switch, and any changes since the backup will be lost.  As 1.5
does not support protobuf encoding, if you roll back to 1.5 after upgrading to
protobuf you will be forced to restore from backup, and you will lose any changes
since you converted to protobuf.  After conversion to protobuf, you should

* kubeadm - fix upgrades with external etcd ([#63925](https://github.com/kubernetes/kubernetes/pull/63925), [@detiber](https://github.com/detiber))

		* Fix false positive "meaningful conflict" detection for strategic merge patch with integer values. ([#44788](https://github.com/kubernetes/kubernetes/pull/44788), [@enisoc](https://github.com/enisoc))

		* Restored the ability of kubectl running inside a pod to consume resource files specifying a different namespace than the one the pod is running in. ([#44862](https://github.com/kubernetes/kubernetes/pull/44862), [@liggitt](https://github.com/liggitt))

* Restored the pre-1.10 behavior of the openstack cloud provider, which uses the instance name as the Kubernetes Node name. This requires instances be named with RFC-1123 compatible names. ([#63903](https://github.com/kubernetes/kubernetes/pull/63903), [@l...

- github.com/certifi/gocertifi: [2c3bb06](https://github.com/certifi/gocertifi/tree/2c3bb06)
- github.com/checkpoint-restore/go-criu/v5: [v5.0.0](https://github.com/checkpoint-restore/go-criu/v5/tree/v5.0.0)
- github.com/cncf/udpa/go: [5459f2c](https://github.com/cncf/udpa/go/tree/5459f2c)
- github.com/cockroachdb/errors: [v1.2.4](https://github.com/cockroachdb/errors/tree/v1.2.4)

* Add extra-args configs to kubernetes-worker charm ([#55334](https://github.com/kubernetes/kubernetes/pull/55334), [@Cynerva](https://github.com/Cynerva))
* Restored kube-proxy's support for 0 values for conntrack min, max, max per core, tcp close wait timeout, and tcp established timeout. ([#55261](https://github.com/kubernetes/kubernetes/pull/55261), [@ncdc](https://github.com/ncdc))

- github.com/aws/aws-sdk-go-v2: [v1.30.1](https://github.com/aws/aws-sdk-go-v2/tree/v1.30.1)
- github.com/aws/smithy-go: [v1.20.3](https://github.com/aws/smithy-go/tree/v1.20.3)
- github.com/checkpoint-restore/go-criu/v6: [v6.3.0](https://github.com/checkpoint-restore/go-criu/tree/v6.3.0)
- github.com/containerd/containerd/api: [v1.7.19](https://github.com/containerd/containerd/tree/api/v1.7.19)

* Restored cAdvisor prometheus metrics to the main port -- a regression that existed in v1.7.0-v1.7.2 ([#49079](https://github.com/kubernetes/kubernetes/pull/49079), [@smarterclayton](https://github.com/smarterclayton))

- DRA: The scheduler plugin prevented abnormal filter runtimes by timing out after 10 seconds. This was configurable via the plugin configuration's `FilterTimeout`. Setting it to zero disabled the timeout and restored the behavior of Kubernetes <= 1.33. ([#132033](https://github.com/kubernetes/kubernetes/pull/132033), [@pohly](https://github.com/pohly)) [SIG Node, Scheduling and Testing]

* Restores --username and --password flags to kubectl ([#75451](https://github.com/kubernetes/kubernetes/pull/75451), [@liggitt](https://github.com/liggitt))