</p>

<h3 id="Tokens">Tokens</h3>

<p>
Tokens form the vocabulary of the Go language.
There are four classes: <i>identifiers</i>, <i>keywords</i>, <i>operators
and punctuation</i>, and <i>literals</i>.  <i>White space</i>, formed from
spaces (U+0020), horizontal tabs (U+0009),
carriage returns (U+000D), and newlines (U+000A),
is ignored except as it separates tokens

- Node information is now embedded into Pod-bound service account tokens as additional metadata. The 'JTI' field is set in issued service account tokens, and this information is embedded as `authentication.kubernetes.io/credential-id` in the user's ExtraInfo. ([#123135](https://github.com/kubernetes/kubernetes/pull/123135), [@munnerz](https://github.com/munnerz))...

 - The default Bootstrap Token created with `kubeadm init` v1.8 expires
 and is deleted after 24 hours by default to limit the exposure of the
 valuable credential. You can create a new Bootstrap Token with
 `kubeadm token create` or make the default token permanently valid by specifying
 `--token-ttl 0` to `kubeadm init`. The default token can later be deleted with
 `kubeadm token delete`.

        </field>
        <field>
          <name>stringFiltering</name>
          <version>4.1.0+</version>
          <description>
            <![CDATA[
            Whether resources are filtered to replace tokens with parameterized values.
            The values are taken from the {@code properties} element and from the properties
            in the files listed in the {@code filters} element.

## Changelog since v1.5.5

### Other notable changes

* kube-up (with gce/gci and gce/coreos providers) now ensures the authentication token file contains correct tokens for the control plane components, even if the file already exists (ensures upgrades and downgrades work successfully) ([#43676](https://github.com/kubernetes/kubernetes/pull/43676), [@liggitt](https://github.com/liggitt))

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/configurati...

powens.png...

- Fix kubelet token cache returning stale tokens when service accounts are recreated with the same name. The token cache is now UID-aware and the new `TokenRequestServiceAccountUIDValidation` feature gate (Beta, enabled by default) validates the TokenRequest UID when set matches the service account UID. ([#132803...

* With this PR, kubectl and other RestClient's using the AuthProvider framework can make OIDC authenticated requests, and, if there is a refresh token present, the tokens will be refreshed as needed. ([#25270](https://github.com/kubernetes/kubernetes/pull/25270), [@bobbyrullo](https://github.com/bobbyrullo))

- Kube-apiserver can now specify `--authentication-token-webhook-version=v1` or `--authorization-webhook-version=v1` to use `v1` TokenReview and SubjectAccessReview API objects when communicating with authentication and authorization webhooks. ([#84768](https://github.com/kubernetes/kubernetes/pull/84768), [@liggitt](https://github.com/liggitt))