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))

  optional bool readOnly = 5;

  // kind expected values are Shared: multiple blob disks per storage account  Dedicated: single blob disk per storage account  Managed: azure managed data disk (only in managed availability set). defaults to shared
  optional string kind = 6;
}

// AzureFile represents an Azure File Service mount on the host and bind mount to the pod.
message AzureFilePersistentVolumeSource {

    * --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

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))...

  - `--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.

- 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))

#### 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 key of the configuration. e.g. true */
    String INDEXER_CLICK_COUNT_ENABLED = "indexer.click.count.enabled";

    /** The key of the configuration. e.g. true */
    String INDEXER_FAVORITE_COUNT_ENABLED = "indexer.favorite.count.enabled";

    /** The key of the configuration. e.g. 5000 */
    String INDEXER_WEBFS_COMMIT_MARGIN_TIME = "indexer.webfs.commit.margin.time";

- 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]