in containers are now `rslave` on Linux by default. To make this default work in all Linux environments the entire mount tree should be marked as shareable, e.g. via `mount --make-rshared /`. All Linux distributions that use systemd already have the root directory mounted as rshared and hence they need not do anything. In Linux environments without systemd we recommend running `mount --make-rshared /` during boot before docker is started, ([@jsafrane](https://github.com/jsafrane))

##...

* You can now resize PersistentVolumes without taking them offline ([ref](https://github.com/kubernetes/enhancements/issues/531))
* You can now set a maximum volume count ([ref](https://github.com/kubernetes/enhancements/issues/554))
* You can now do environment variable expansion in a subpath mount. ([ref](https://github.com/kubernetes/enhancements/issues/559))

- Added support in the kubelet's image pull credential tracking for service account-based verification. When an image was pulled using service account credentials via external credential providers, subsequent Pods using the same service account (UID, name, and namespace) could access the cached image without re-authentication for the lifetime of that service account. ([#132771](https://github.com/kubernetes/kubernetes/pull/132771), [@aramase](https://github.com/aramase))...

resource belongs to. ([#43338](https://github.com/kubernetes/kubernetes/pull/43338), [@fabianofranz](https://github.com/fabianofranz))

* `--service-account-lookup` now defaults to true, requiring the Secret API object containing the token to exist in order for a service account token to be valid. This enables service account tokens to be revoked by deleting the Secret object containing the token. ([#44071](https://github.com/kubernetes/kubernetes/pull/44071), [@liggitt](https://github.com/liggitt))...

    * --alpha-endpoint-reconciler-type=(master-count, lease, none) (default
    * "master-count"). The original reconciler is 'master-count'. The 'lease'
    * reconciler uses the storageapi and a TTL to keep alive an endpoint within the
    * `kube-apiserver-endpoint` storage namespace. The 'none' reconciler is a noop

  - `--service-account-issuer`, should be set to a URL identifying the API server that will be stable over the cluster lifetime.
  - `--service-account-key-file`, set to one or more files containing one or more public keys used to verify tokens.

- kube-apiserver: `--service-account-max-token-expiration` can now be used in combination with an external token signer `--service-account-signing-endpoint`, as long as the `--service-account-max-token-expiration` is not longer than the external token signer's max expiration. ([#129816](https://github.com/kubernetes/kubernetes/pull/129816), [@sambdavidson](h...

#### Storage

* [stable] Mount options

  * The ability to specify mount options for volumes is moved from beta to stable.

  * A new `MountOptions` field in the `PersistentVolume` spec is available to specify mount options. This field replaces an annotation.

  * A new `MountOptions` field in the `StorageClass` spec allows configuration of mount options for dynamically provisioned volumes.

- The alpha feature `ServiceAccountIssuerDiscovery` enables publishing OIDC discovery information and service account token verification keys at `/.well-known/openid-configuration` and `/openid/v1/jwks` endpoints by API servers configured to issue service account tokens. ([#80724](https://github.com/kubernetes/kubernetes/pull/80724), [@cceckman](https://github.com/cceckman)) [SIG API Machinery, Auth, Cluster Lifecycle and Testing]

- Fixed scanning of failed iSCSI targets. ([#74306](https://github.com/kubernetes/kubernetes/pull/74306), [@jsafrane](https://github.com/jsafrane))
- StorageOS volume plugin updated to fix an issue where volume mount succeeds even if request to mount via StorageOS API fails. ([#69782](https://github.com/kubernetes/kubernetes/pull/69782), [@darkowlzz](https://github.com/darkowlzz))