* Upgrade Elasticsearch/Kibana to 5.5.1 in fluentd-elasticsearch addon ([#48722](https://github.com/kubernetes/kubernetes/pull/48722), [@aknuds1](https://github.com/aknuds1))
        * Switch to basing our image of Elasticsearch in fluentd-elasticsearch addon off the official one
        * Switch to the official image of Kibana in fluentd-elasticsearch addon

* Addon manager supports HA masters. ([#55466](https://github.com/kubernetes/kubernetes/pull/55466), [@x13n](https://github.com/x13n))
* - Add PodSecurityPolicies for cluster addons ([#55509](https://github.com/kubernetes/kubernetes/pull/55509), [@tallclair](https://github.com/tallclair))
    * - Remove SSL cert HostPath volumes from heapster addons

* [stackdriver addon] Bump prometheus-to-sd to v0.5.0 to pick up security fixes. ([#75362](https://github.com/kubernetes/kubernetes/pull/75362), [@serathius](https://github.com/serathius))
    * [fluentd-gcp addon] Bump fluentd-gcp-scaler to v0.5.1 to pick up security fixes.
    * [fluentd-gcp addon] Bump event-exporter to v0.2.4 to pick up security fixes.

	* ip-masq-agent is now on by default for GCE ([#47794](https://github.com/kubernetes/kubernetes/pull/47794), [@dnardo](https://github.com/dnardo))

  * Add ip-masq-agent addon to the addons folder which is used in GCE if `--non-masquerade-cidr` is set to 0/0 ([#46038](https://github.com/kubernetes/kubernetes/pull/46038), [@dnardo](https://github.com/dnardo))

### Other notable changes

* [stackdriver addon] Bump prometheus-to-sd to v0.5.0 to pick up security fixes. ([#75362](https://github.com/kubernetes/kubernetes/pull/75362), [@serathius](https://github.com/serathius))
    * [fluentd-gcp addon] Bump fluentd-gcp-scaler to v0.5.1 to pick up security fixes.
    * [fluentd-gcp addon] Bump event-exporter to v0.2.4 to pick up security fixes.

### Other notable changes

* [fluentd-gcp-scaler addon] Bump fluentd-gcp-scaler to 0.4 to pick up security fixes. ([#67691](https://github.com/kubernetes/kubernetes/pull/67691), [@loburm](https://github.com/loburm))
    * [prometheus-to-sd addon] Bump prometheus-to-sd to 0.3.1 to pick up security fixes, bug fixes and new features.
    * [event-exporter addon] Bump event-exporter to 0.2.3 to pick up security fixes.

* [stackdriver addon] Bump prometheus-to-sd to v0.5.0 to pick up security fixes. ([#75362](https://github.com/kubernetes/kubernetes/pull/75362), [@serathius](https://github.com/serathius))
    * [fluentd-gcp addon] Bump fluentd-gcp-scaler to v0.5.1 to pick up security fixes.
    * [fluentd-gcp addon] Bump event-exporter to v0.2.4 to pick up security fixes.

* [stackdriver addon] Bump prometheus-to-sd to v0.5.0 to pick up security fixes. ([#75362](https://github.com/kubernetes/kubernetes/pull/75362), [@serathius](https://github.com/serathius))
    * [fluentd-gcp addon] Bump fluentd-gcp-scaler to v0.5.1 to pick up security fixes.
    * [fluentd-gcp addon] Bump event-exporter to v0.2.4 to pick up security fixes.

### GCP

- [stackdriver addon] Bumped prometheus-to-sd to v0.5.0 to pick up security fixes.
[fluentd-gcp addon] Bumped fluentd-gcp-scaler to v0.5.1 to pick up security fixes.
[fluentd-gcp addon] Bumped event-exporter to v0.2.4 to pick up security fixes.
[fluentd-gcp addon] Bumped prometheus-to-sd to v0.5.0 to pick up security fixes.

  - ip-mask-agent addon starts to use the label `node.kubernetes.io/masq-agent-ds-ready` instead of `beta.kubernetes.io/masq-agent-ds-ready` as its node selector.
  - kube-proxy addon starts to use the label `node.kubernetes.io/kube-proxy-ds-ready` instead of `beta.kubernetes.io/kube-proxy-ds-ready` as its node selector.