## 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))

This API provided status of etcd, kube-scheduler, and kube-controller-manager components, but only worked when those components were local to the API server, and when kube-scheduler and kube-controller-manager exposed unsecured health endpoints. Instead of this API, etcd health is included in the kube-apiserver health check and kube-scheduler/kube-controller-manager health checks can be made directly against those components' health endpoints. ([#93570](https://github.com/kubernetes/kubernetes/pull/93570),...

This API provided status of etcd, kube-scheduler, and kube-controller-manager components, but only worked when those components were local to the API server, and when kube-scheduler and kube-controller-manager exposed unsecured health endpoints. Instead of this API, etcd health is included in the kube-apiserver health check and kube-scheduler/kube-controller-manager health checks can be made directly against those components' health endpoints. ([#93570](https://github.com/kubernetes/kubernetes/pull/93570),...

### Deploy a more secure control plane with kubeadm

flag --port=0 to kube-controller-manager and kube-scheduler manifests to disable insecure serving. Without this flag the components by default serve (e.g. /metrics) insecurely on the default node interface (controlled by --address). Users that wish to override this behavior and enable insecure serving can pass a custom --port=X via kubeadm's "extraArgs" mechanic for these components. ([#92720](https://github.com/kubernetes/kubernetes/pull/92720), [@neolit123](https://github.com/neolit123)) [SIG Cluster...

- The kubelet now creates an iptables chain named `KUBE-IPTABLES-HINT` in
  the `mangle` table. Containerized components that need to modify iptables
  rules in the host network namespace can use the existence of this chain
  to more-reliably determine whether the system is using iptables-legacy or

- If upgrading Cluster Federation components from 1.3.x, please ensure your cluster name is a valid DNS label (#30956, @nikhiljindal)
- kubelet's `--config` flag has been deprecated, use `--pod-manifest-path` instead (#29999, @mtaufen)

    - [Cluster Autoscaler](#cluster-autoscaler)
    - [Deployment](#deployment)
    - [Federation](#federation)
    - [Internal Storage Layer](#internal-storage-layer)
    - [Node Components](#node-components)
    - [kubectl](#kubectl)
    - [RBAC](#rbac)
    - [Scheduling](#scheduling)
    - [Service](#service)
    - [StatefulSet](#statefulset)
    - [Volumes](#volumes)

- Added to `MutableFeatureGate` the ability to override the default setting of feature gates, to allow default-enabling a feature on a component-by-component basis instead of for all affected components simultaneously. ([#122647](https://github.com/kubernetes/kubernetes/pull/122647), [@benluddy](https://github.com/benluddy))

## Changelog since v1.15.6

### Other notable changes

* Change GCP ILB firewall names to contain the "k8s-fw-" prefix like the rest of the firewall rules. This is needed for consistency and also for other components to identify the firewall rule as k8s/service-controller managed. ([#84622](https://github.com/kubernetes/kubernetes/pull/84622), [@prameshj](https://github.com/prameshj))