Remove initializers from doc

content/en/docs/reference/access-authn-authz/admission-controllers.md

@@ -334,13 +334,6 @@ Examples of information you might put here are:
 
 In any case, the annotations are provided by the user and are not validated by Kubernetes in any way. In the future, if an annotation is determined to be widely useful, it may be promoted to a named field of ImageReviewSpec.
 
-### Initializers (alpha) {#initializers}
-
-The admission controller determines the initializers of a resource based on the existing
-`InitializerConfiguration`s. It sets the pending initializers by modifying the
-metadata of the resource to be created.
-For more information, please check [Dynamic Admission Control](/docs/reference/access-authn-authz/extensible-admission-controllers/).
-
 ### LimitPodHardAntiAffinityTopology {#limitpodhardantiaffinitytopology}
 
 This admission controller denies any pod that defines `AntiAffinity` topology key other than

content/en/docs/reference/access-authn-authz/extensible-admission-controllers.md

@@ -5,6 +5,7 @@ reviewers:
 - whitlockjc
 - caesarxuchao
 - deads2k
+- liggitt
 title: Dynamic Admission Control
 content_template: templates/concept
 weight: 40
@@ -19,16 +20,14 @@ the following:
 * They need to be compiled into kube-apiserver.
 * They are only configurable when the apiserver starts up.
 
-Two features, *Admission Webhooks* (beta in 1.9) and *Initializers* (alpha),
-address these limitations. They allow admission controllers to be developed
-out-of-tree and configured at runtime.
+*Admission Webhooks* (beta in 1.9) addresses these limitations. It allows
+admission controllers to be developed out-of-tree and configured at runtime.
+
+This page describes how to use Admission Webhooks.
 
-This page describes how to use Admission Webhooks and Initializers.
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-## Admission Webhooks
-
 ### What are admission webhooks?
 
 Admission webhooks are HTTP callbacks that receive admission requests and do
@@ -196,116 +195,4 @@ users:
 ```
 
 Of course you need to set up the webhook server to handle these authentications.
-
-## Initializers
-
-### What are initializers?
-
-*Initializer* has two meanings:
-
-* A list of pending pre-initialization tasks, stored in every object's metadata
-  (e.g., "AddMyCorporatePolicySidecar").
-
-* A user customized controller, which actually performs those tasks. The name of the task
-  corresponds to the controller which performs the task. For clarity, we call
-  them *initializer controllers* in this page.
-
-Once the controller has performed its assigned task, it removes its name from
-the list. For example, it may send a PATCH that inserts a container in a pod and
-also removes its name from `metadata.initializers.pending`. Initializers may make
-mutations to objects.
-
-Objects which have a non-empty initializer list are considered uninitialized,
-and are not visible in the API unless specifically requested by using the query parameter,
-`?includeUninitialized=true`.
-
-### When to use initializers?
-
-Initializers are useful for admins to force policies (e.g., the
-[AlwaysPullImages](/docs/reference/access-authn-authz/admission-controllers/#alwayspullimages)
-admission controller), or to inject defaults (e.g., the
-[DefaultStorageClass](/docs/reference/access-authn-authz/admission-controllers/#defaultstorageclass)
-admission controller), etc.
-
-{{< note >}}
-If your use case does not involve mutating objects, consider using
-external admission webhooks, as they have better performance.
-{{< /note >}}
-
-### How are initializers triggered?
-
-When an object is POSTed, it is checked against all existing
-`initializerConfiguration` objects (explained below). For all that it matches,
-all `spec.initializers[].name`s are appended to the new object's
-`metadata.initializers.pending` field.
-
-An initializer controller should list and watch for uninitialized objects, by
-using the query parameter `?includeUninitialized=true`. If using client-go, just
-set
-[listOptions.includeUninitialized](https://github.com/kubernetes/kubernetes/blob/v1.7.0-rc.1/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types.go#L315)
-to true.
-
-For the observed uninitialized objects, an initializer controller should first
-check if its name matches `metadata.initializers.pending[0]`. If so, it should then
-perform its assigned task and remove its name from the list.
-
-### Enable initializers alpha feature
-
-*Initializers* is an alpha feature, so it is disabled by default. To turn it on,
-you need to:
-
-* Include "Initializers" in the `--enable-admission-plugins` flag when starting
-  `kube-apiserver`. If you have multiple `kube-apiserver` replicas, all should
-  have the same flag setting.
-
-* Enable the dynamic admission controller registration API by adding
-  `admissionregistration.k8s.io/v1alpha1` to the `--runtime-config` flag passed
-  to `kube-apiserver`, e.g.
-  `--runtime-config=admissionregistration.k8s.io/v1alpha1`. Again, all replicas
-  should have the same flag setting.
-
-### Deploy an initializer controller
-
-You should deploy an initializer controller via the [deployment
-API](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#deployment-v1beta1-apps).
-
-### Configure initializers on the fly
-
-You can configure what initializers are enabled and what resources are subject
-to the initializers by creating `initializerConfiguration` resources.
-
-You should first deploy the initializer controller and make sure that it is
-working properly before creating the `initializerConfiguration`. Otherwise, any
-newly created resources will be stuck in an uninitialized state.
-
-The following is an example `initializerConfiguration`:
-
-```yaml
-apiVersion: admissionregistration.k8s.io/v1alpha1
-kind: InitializerConfiguration
-metadata:
-  name: example-config
-initializers:
-  # the name needs to be fully qualified, i.e., containing at least two "."
-  - name: podimage.example.com
-    rules:
-      # apiGroups, apiVersion, resources all support wildcard "*".
-      # "*" cannot be mixed with non-wildcard.
-      - apiGroups:
-          - ""
-        apiVersions:
-          - v1
-        resources:
-          - pods
-```
-
-After you create the `initializerConfiguration`, the system will take a few
-seconds to honor the new configuration. Then, `"podimage.example.com"` will be
-appended to the `metadata.initializers.pending` field of newly created pods. You
-should already have a ready "podimage" initializer controller that handles pods
-whose `metadata.initializers.pending[0].name="podimage.example.com"`. Otherwise
-the pods will be stuck in an uninitialized state.
-
-Make sure that all expansions of the `<apiGroup, apiVersions, resources>` tuple
-in a `rule` are valid. If they are not, separate them in different `rules`.
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