AutoscalingContext is basically a configuration and few static helpers
and API handles.
ClusterStateRegistry is state and thus moved to other state-keeping
objects.
Currently we track if those nodes can be removed and only
skip them at the execution step. Since checking if node is
unneeded is pretty expensive it's better to filter them out
early.
Adds a new optional flag named `configmap` to specify the name of a configmap containing node group specs.
The configmap is polled every `scan-interval` seconds to reconfigure cluster-autoscaler dynamically at runtime.
Example usage:
```
./cluster-autoscaler --v=4 --cloud-provider=aws --skip-nodes-with-local-storage=false --logtostderr --leader-elect=false --configmap=cluster-autoscaler --logtostderr
```
The configmap would look like:
```yaml
kind: ConfigMap
apiVersion: v1
metadata:
name: cluster-autoscaler
namespace: kube-system
data:
settings: |-
{
"nodeGroups": [
{
"minSize": 1,
"maxSize": 2,
"name": "kubeawstest-nodepool1-AutoScaleWorker-1VWD4GAVG35L5"
}
]
}
```
Other notes:
* Make namespace defaults to "kube-system"
according to https://github.com/kubernetes/contrib/pull/2226#discussion_r94144267
* Trigger a full-recreate on a configuration change
according to https://github.com/kubernetes/contrib/pull/2226#issuecomment-269617410
* Introduced `autoscaler/` and moved all the dynamic/recreatable-at-runtime parts of autoscaler into there (Update: the package is now named `core` according to https://github.com/kubernetes/contrib/pull/2226#issuecomment-273071663)
* Extracted the core of CA(=`func Run()` in `main.go`) into `Autoscaler`
* `DynamicAutoscaler` is a wrapper around `Autoscaler` which achieves reconfiguration of CA by recreating an `Autoscaler` instance on a configmap change.
* Moved `scale_down*.go`, `scale_up*.go` and `utils*.go` into the `autoscaler` package accordingly because they seemed to be meant to be collocated in the same package as the core of CA (which is now implemented as `Autoscaler`)
* Moved the `createEventRecorder` func from the `main` package to the `utils/kubernetes` package to make it importable from both `main` and `autoscaler`
Krzysztof Jastrzebski
Karol Gołąb
Marcin Wielgus
Aleksandra Malinowska
Maciej Pytel
Clayton Coleman
Yusuke Kuoka