Automatic merge from submit-queue (batch tested with PRs 54556, 55379, 55881, 55891, 55705). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Ensure config file exists before loading configuration in imagePolicyWebhook
**What this PR does / why we need it**:
ensure config file exists before loading configuration in imagePolicyWebhook
**Which issue(s) this PR fixes**
Fixes#55378
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 52792, 48963). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Fix range for min value in imagepolicy admission
**What this PR does / why we need it**:
This makes the range for imagepolicy admission work properly. Currently if we specify `1s` for the value of `AllowTTL` or `DenyTTL` in the configuration yaml, we get a message like the following:
```
Error: failed to initialize plugins: Couldn't init admission plugin "ImagePolicyWebhook": valid value is between 1s and 30m0s, got 1s
```
This is due to a wrong comparison which is fixed in this PR. The rest of the PR just adds tests for this behaviour.
Automatic merge from submit-queue (batch tested with PRs 51310, 51458, 47636). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
remove useless allocation of map
This one-element map is only used for checking api. Remove it and
simplify the code.
**Release note**:
```
NONE
```
Automatic merge from submit-queue
Update admission control args in imagepolicy comment
Use '--admission-control-config-file' rather than
'--admission-controller-config-file'
**Release note**:
```release-note
NONE
```
this is a two stage refactor when done there will be no init block in admission plugins.
Instead all plugins expose Register function which accept admission.Plugins instance.
The registration to global plugin registry happens inside Register func.
Automatic merge from submit-queue
make client-go more authoritative
Builds on https://github.com/kubernetes/kubernetes/pull/40103
This moves a few more support package to client-go for origination.
1. restclient/watch - nodep
1. util/flowcontrol - used interface
1. util/integer, util/clock - used in controllers and in support of util/flowcontrol
Automatic merge from submit-queue (batch tested with PRs 39807, 37505, 39844, 39525, 39109)
Admission control support for versioned configuration files
**What this PR does / why we need it**:
Today, the `--admission-control-config-file=` argument takes an opaque file that is shared across all admission controllers to provide configuration. This file is not well-versioned and it's shared across multiple plug-ins. Some plugins take file based configuration (`ImagePolicyWebhook`) and others abuse flags to provide configuration because we lacked a good example (`InitialResources`). This PR defines a versioned configuration format that we can use moving forward to provide configuration input to admission controllers that is well-versioned, and does not require the addition of new flags.
The sample configuration file would look as follows:
```
apiVersion: componentconfig/v1alpha1
kind: AdmissionConfiguration
plugins:
- name: "ImagePolicyWebhook"
path: "image-policy-webhook.json"
```
The general behavior is each plugin that requires additional configuration is enumerated by name. An alternate file location is provided for its specific configuration, or the configuration can be embedded as a raw extension via the configuration section.
**Special notes for your reviewer**:
A follow-on PR will be needed to make `ImagePolicyWebhook` to use versioned configuration. This PR maintains backwards compatibility by ignoring configuration it cannot understand and therefore treating the file as opaque. I plan to make use of this PR to complete https://github.com/kubernetes/kubernetes/pull/36765 which attempts to allow more configuration parameters to the `ResourceQuota` admission plugin.
