* 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.

	* Mechanism of adding `federation domain maps` to kube-dns deployment via `--federations` flag is superseded by adding/updating `federations` key in `kube-system/kube-dns` configmap. If user is using kubefed tool to join cluster federation, adding federation domain maps to kube-dns is already taken care by `kubefed join` and does not need further action.

### 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.

### 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.

* 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

- kubeadm: `kubeadm upgrade node` now supports `addon` and `post-upgrade` phases. Users can use `kubeadm upgrade node phase addon` to execute the addon upgrade, or use `kubeadm upgrade node --skip-phases addon` to skip the addon upgrade. If you were previously skipping an addon subphase on `kubeadm init` you should now skip the same addon when calling `kubeadm upgrade apply` and `kubeadm upgrade node`. Currently, the `post-upgrade` phase is...

* [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.

- `kube-apiserver` added: