- Alpha implementation of Kubectl Command Headers: SIG CLI KEP 859 enabled when KUBECTL_COMMAND_HEADERS environment variable set on the client command line. ([#98952](https://github.com/kubernetes/kubernetes/pull/98952), [@seans3](https://github.com/seans3))
- Base-images: Update to debian-iptables:buster-v1.4.0
  - Uses iptables 1.8.5

   ([#123341](https://github.com/kubernetes/kubernetes/pull/123341), [@neolit123](https://github.com/neolit123))
- kubectl `port-forward` over websockets (tunneling SPDY) can now be enabled using an `Alpha` feature flag environment variable: KUBECTL_PORT_FORWARD_WEBSOCKETS=true. The API Server being communicated to must *also* have an `Alpha` feature flag enabled: PortForwardWebsockets.

- Adds `OpenAPIV3SchemaInterface` to `DiscoveryClient` and its variants for fetching OpenAPI v3 schema documents. ([#108992](https://github.com/kubernetes/kubernetes/pull/108992), [@alexzielenski](https://github.com/alexzielenski))

- KCM specific args can be passed with `/cluster` script, without affecting CCM. New variable name: `KUBE_CONTROLLER_MANAGER_TEST_ARGS`. ([#120524](https://github.com/kubernetes/kubernetes/pull/120524), [@jprzychodzen](https://github.com/jprzychodzen)) [SIG Cloud Provider]

* AWS volumes: Use /dev/xvdXX names with EC2 ([#27628](https://github.com/kubernetes/kubernetes/pull/27628), [@justinsb](https://github.com/justinsb))
* Add a test config variable to specify desired Docker version to run on GCI. ([#26813](https://github.com/kubernetes/kubernetes/pull/26813), [@wonderfly](https://github.com/wonderfly))

- New `KUBECACHEDIR` environment variable was introduced to override default discovery cache directory which is `$HOME/.kube/cache`. ([#109479](https://github.com/kubernetes/kubernetes/pull/109479), [@ardaguclu](https://github.com/ardaguclu))

   * bug where the loop that connects a Listener to each of the futures would die on the last
   * loop-check as done() on ListFuture nulled out the variable being looped over (the list of
   * futures).
   */
  public void testAllAsList_doneFutures() throws Exception {
    // Create input and output
    SettableFuture<String> future1 = SettableFuture.create();

   * bug where the loop that connects a Listener to each of the futures would die on the last
   * loop-check as done() on ListFuture nulled out the variable being looped over (the list of
   * futures).
   */
  public void testAllAsList_doneFutures() throws Exception {
    // Create input and output
    SettableFuture<String> future1 = SettableFuture.create();

- Users should not rely on unsupported CRON_TZ variable when specifying schedule, both the API server and cronjob controller will emit warnings pointing to https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/ containing explanation ([#106455](https://github.com/kubernetes/kubernetes/pull/106455),...

        docSettingRewriteRuleList.add(rule);
    }

    /**
     * Gets the resource path for configuration files, checking type-specific variants first.
     *
     * @param basePath the base path for resources
     * @param type     the search engine type
     * @param path     the relative path to the resource
     * @return the full resource path