### SIG Storage

      localCache.put(key, value);
    }

    @Override
    public void putAll(Map<? extends K, ? extends V> m) {
      localCache.putAll(m);
    }

    @Override
    public void invalidate(Object key) {
      checkNotNull(key);
      localCache.remove(key);
    }

    @Override
    public void invalidateAll(Iterable<?> keys) {
      localCache.invalidateAll(keys);
    }

- Kubeadm now propagates proxy environment variables to kube-proxy ([#84559](https://github.com/kubernetes/kubernetes/pull/84559), [@yastij](https://github.com/yastij))
- Update the latest validated version of Docker to 19.03 ([#84476](https://github.com/kubernetes/kubernetes/pull/84476), [@neolit123](https://github.com/neolit123))

// HEAD requests on an object validates the existence of the object.
// The responses for fetching the object when If-Modified-Since
// and If-Unmodified-Since headers set are validated.
// If-Modified-Since - Return the object only if it has been modified since the specified time, else return a 304 (not modified).

Continuous integration builds use Docker versions 1.11.2, 1.12.6, 1.13.1,
and 17.03.2. These versions were validated on Kubernetes 1.8. However,
consult an appropriate installation or upgrade guide before deciding what
versions of Docker to use.

- Docker 1.13.1 and 17.03.2

    - Shared PID namespace, live-restore, and overlay2 were validated.

    - **Known issues**

[CRD Validation Expression Language](https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/2876-crd-validation-expression-language/README.mdv) is promoted to beta, which makes it possible to declare how custom resources are validated using the [Common Expression Language (CEL)](https://github.com/google/cel-spec). Please see the [validation rules](https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#validation-rules) guide.

* **Other objects**: no changes unless you explicitly request orphaning.

## Action Required Before Upgrading

- If you are using Kubernetes to manage `docker` containers, please be aware Kubernetes has been validated to work with docker 1.9.1, docker 1.11.2 (#23397), and docker 1.12.0 (#28698)

* Rescheduler is v0.4.0, compared with v0.3.1 in v1.10 ([#65454](https://github.com/kubernetes/kubernetes/pull/65454))
* The validated docker versions are the same as for v1.10: 1.11.2 to 1.13.1 and 17.03.x (ref)
* The Go version is go1.10.2, as compared to go1.9.3 in v1.10. ([#63412](https://github.com/kubernetes/kubernetes/pull/63412))

Google Cloud required that workloads (e.g. Deployments, DaemonSets, etc.) which used `PersistentDisk` volumes were using them in read-only mode.  This validation provided very little value at relatively host implementation cost, and will no longer be validated.  If this is a problem for a specific use-case, please set the `SkipReadOnlyValidationGCE` gate to false to re-enable the validation, and file a Kubernetes bug with details. ([#121083](https://github.com/kubernetes/kubernetes/pull/121083), [@tho...

* Docker versions 1.10.3, 1.11.2, 1.12.6 have been validated

    * Docker version 1.12.6 known issues

        * overlay2 driver not fully supported

        * live-restore not fully supported

        * no shared pid namespace support