### SIG-cluster-lifecycle

In 1.12, SIG Cluster lifecycle has focused on improving the user experience in kubeadm, by fixing a number of bugs and adding some new important features.

Here is a list of some of the changes that have been made to kubeadm:

- Kubeadm internal config has been promoted to `v1alpha3`:
  - `v1alpha1` has been removed.

  optional NodeAffinity nodeAffinity = 1;

  // Describes pod affinity scheduling rules (e.g. co-locate this pod in the same node, zone, etc. as some other pod(s)).
  // +optional
  optional PodAffinity podAffinity = 2;

  // Describes pod anti-affinity scheduling rules (e.g. avoid putting this pod in the same node, zone, etc. as some other pod(s)).
  // +optional
  optional PodAntiAffinity podAntiAffinity = 3;
}

  - [Changelog since v1.20.5](#changelog-since-v1205)
  - [Important Security Information](#important-security-information-1)
    - [CVE-2021-25735: Validating Admission Webhook does not observe some previous fields](#cve-2021-25735-validating-admission-webhook-does-not-observe-some-previous-fields)
  - [Changes by Kind](#changes-by-kind-9)
    - [API Change](#api-change-2)
    - [Feature](#feature-5)
    - [Bug or Regression](#bug-or-regression-9)

* kubeadm: Fixes a small bug where `--config` and `--skip-*` flags couldn't be passed at the same time in validation. ([#49498](https://github.com/kubernetes/kubernetes/pull/49498), [@luxas](https://github.com/luxas))

- Sometimes, the scheduler incorrectly placed a pod in the "unschedulable" queue instead of the "backoff" queue. This happened when some plugin previously declared the pod as "unschedulable" and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the "active" queue. ([#120334](https://github.com/kubernetes/kubernetes/pull/120334),...

Before updating to 1.9, you are strongly recommended to back up your etcd data. Consult the installation procedure you are using (kargo, kops, kube-up, kube-aws, kubeadm etc) for specific advice.

- Sometimes, the scheduler incorrectly placed a pod in the "unschedulable" queue instead of the "backoff" queue. This happened when some plugin previously declared the pod as "unschedulable" and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the "active" queue. ([#120334](https://github.com/kubernetes/kubernetes/pull/120334),...

- In some cases, a Flex volume resize may leave a PVC with erroneous Resizing condition even after volume has been successfully expanded. Users may choose to delete the condition, but it is not required. ([#71470](https://github.com/kubernetes/kubernetes/issues/71470))

- Using `--log-file` is known to be problematic in 1.15. This presents as things being logged multiple times to the same file. The behaviour and details of this issue, as well as some preliminary attempts at fixing it are documented [here](https://github.com/kubernetes/kubernetes/issues/78734#issuecomment-501372131)

- The feature gate was mentioned as `csiMigrationRBD` where it should have been `CSIMigrationRBD` to be in parity with other migration plugins. This release correct the same and keep it as `CSIMigrationRBD`.
  
  users who have configured this feature gate as `csiMigrationRBD` has to reconfigure the same to `CSIMigrationRBD` from this release. ([#107554](https://github.com/kubernetes/kubernetes/pull/107554), [@humblec](https://github.com/humblec)) [SIG Storage]