// Pods are only limited to this list if this service account has a "kubernetes.io/enforce-mountable-secrets" annotation set to "true".
  // This field should not be used to find auto-generated service account token secrets for use outside of pods.
  // Instead, tokens can be requested directly using the TokenRequest API, or service account token secrets can be manually created.

* The `kube-cloud-controller-manager` flag `--service-account-private-key-file` was non-functional and is now deprecated. ([#50289](https://github.com/kubernetes/kubernetes/pull/50289), [@liggitt](https://github.com/liggitt))
    * The `kube-cloud-controller-manager` flag `--use-service-account-credentials` is now honored consistently, regardless of whether `--service-account-private-key-file` was specified.

### CSI Service Account Token

`kube-controller-manager`: The `LegacyServiceAccountTokenCleanUp` feature gate is now `beta` and enabled by default. When enabled, legacy auto-generated service account token secrets are auto-labeled with a `kubernetes.io/legacy-token-invalid-since` label if the credentials have not been used in the time specified by `--legacy-service-account-token-clean-up-period` (defaulting to one year), **and** are referenced from the `.secrets` list of a ServiceAccount object, **and**  are not referenced from pods....

and enabled by default. When enabled, Secret API objects containing service account tokens are no longer auto-generated for every ServiceAccount. Use the [TokenRequest](https://kubernetes.io/docs/reference/kubernetes-api/authentication-resources/token-request-v1/) API to acquire service account tokens, or if a non-expiring token is required, create a Secret API object for the token controller to populate with a service account token by following this [guide](https://kubernetes.io/docs/concepts/conf...

Kubernetes where users may be able to launch containers that bypass the mountable secrets policy enforced by the ServiceAccount admission plugin when using ephemeral containers. The policy ensures pods running with a service account may only reference secrets specified in the service account's secrets field. Kubernetes clusters are only affected if the ServiceAccount admission plugin and the `kubernetes.io/enforce-mountable-secrets` annotation are used together with ephemeral containers.

**Note**:...

unprivileged pods, using the proxy to perform privileged storage operations on the node.

Another feature moving to GA in v1.22 is CSI Service Account Token support. This feature allows CSI drivers to use pods' [bound service account tokens](https://kubernetes.io/docs/reference/access-authn-authz/service-accounts-admin/#bound-service-account-token-volume) instead of a more privileged identity. It also provides control over to re-publishing these volumes, so that short-lived tokens can be refreshed....

- `kube-controller-manager`: The `LegacyServiceAccountTokenCleanUp` feature gate
  is now available as alpha (off by default). When enabled, the `legacy-service-account-token-cleaner`
  controller loop removes service account token secrets that have not been used
  in the time specified by `--legacy-service-account-token-clean-up-period` (defaulting
  to one year), **and are** referenced from the `.secrets` list of a ServiceAccount

- Some apiserver metrics were changed, as follows.
  - `priority_level_seat_count_samples` is replaced with `priority_level_seat_utilization`, which samples every nanosecond rather than every millisecond; the old metric conveyed utilization despite its name.
  - `priority_level_seat_count_watermarks` is removed.

- This PR adds the following metrics for API Priority and Fairness.
  - **apiserver_flowcontrol_priority_level_seat_count_samples**: histograms of seats occupied by executing requests (both regular and final-delay phases included), broken down by priority_level; the observations are taken once per millisecond.