- Added a path `/header?key=` to `agnhost netexec` allowing one to view what the header value is of the incoming request.

  Ex:
  ```
  $ curl -H "X-Forwarded-For: something" 172.17.0.2:8080/header?key=X-Forwarded-For
  something
  ```
   ([#107796](https://github.com/kubernetes/kubernetes/pull/107796), [@alexanderConstantinescu](https://github.com/alexanderConstantinescu))

or `/etc/sysconfig/kubelet`, depending...

- Some of the in-tree storage drivers indicate support for the `MetricsProvider` interface, but fail to configure this...

### Instrumentation

In v1.9 we focused on improving stability of the components owned by the SIG, including Heapster, Custom Metrics API adapters for Prometheus, and Stackdriver.

### Bug or Regression

- Currently, NodeAdded QueueingHint could not always be called because of the internal feature called preCheck.
  It's definitely not something expected for plugin developers,
  and we're trying to eventually remove preCheck completely to fix this.
  Until then we'll register UpdateNodeTaint event for plugins that have NodeAdded event, but don't have UpdateNodeTaint event.

### Volumes
* StorageClass pre-installed and set as default on Azure, AWS, GCE, OpenStack, and vSphere.
  * This is something to pay close attention to if you’ve been using Kubernetes for a while, because it changes the default behavior of PersistentVolumeClaim objects on these clouds.

### SIG-autoscaling

SIG Autoscaling focused on improving the Horizontal Pod Autoscaling API and algorithm:
- We released autoscaling/v2beta2, which cleans up and unifies the API
- We improved readiness detection and smoothing to work well in a larger variety or use cases

### SIG-Azure

Sig Azure was focused on two primary new alpha features:
- Adding Azure Availability Zones support to cloud provider.