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Fix typos and add a paragraph for initializers doc (#4369)

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* Fix typos and add a paragraph for initializers doc

- Fixed a few consistency issues and typos in the doc
- Also fixed an username typo in assignees
- Added a paragraph explaining how the example initializerconfiguration will
  be applied once it is created.

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

* Add .pending to metadata.initializers, re-wording

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>
This commit is contained in:
Ahmet Alp Balkan
2017-07-31 23:15:39 -07:00
committed by Andrew Chen
parent 11238eea0e
commit acef396611
1 changed files with 15 additions and 11 deletions
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docs/admin/extensible-admission-controllers.md
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@@ -3,7 +3,7 @@ assignees:
- smarterclayton - smarterclayton
- lavalamp - lavalamp
- whitlockjc - whitlockjc
- caesrxuchao - caesarxuchao
title: Dynamic Admission Control title: Dynamic Admission Control
--- ---
@@ -41,7 +41,7 @@ This page describes how to use Initializers and External Admission Webhooks.
Once the controller has performed its assigned task, it removes its name from 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 the list. For example, it may send a PATCH that inserts a container in a pod and
also removes its name from `metadata.initializers`. Initializers may make also removes its name from `metadata.initializers.pending`. Initializers may make
mutations to objects. mutations to objects.
Objects which have a non-empty initializer list are considered uninitialized, Objects which have a non-empty initializer list are considered uninitialized,
@@ -64,7 +64,7 @@ external admission webhooks, as they have better performance.
When an object is POSTed, it is checked against all existing When an object is POSTed, it is checked against all existing
`initializerConfiguration` objects (explained below). For all that it matches, `initializerConfiguration` objects (explained below). For all that it matches,
all `spec.initializers[].name`s are appended to the new object's all `spec.initializers[].name`s are appended to the new object's
`metadata.initializers` field. `metadata.initializers.pending` field.
An initializer controller should list and watch for uninitialized objects, by An initializer controller should list and watch for uninitialized objects, by
using the query parameter `?includeUninitialized=true`. If using client-go, just using the query parameter `?includeUninitialized=true`. If using client-go, just
@@ -73,7 +73,7 @@ set
to true. to true.
For the observed uninitialized objects, an initializer controller should first For the observed uninitialized objects, an initializer controller should first
check if its name matches `metadata.initializers[0]`. If so, it should then 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. perform its assigned task and remove its name from the list.
### Enable initializers alpha feature ### Enable initializers alpha feature
@@ -99,13 +99,13 @@ API](/docs/api-reference/{{page.version}}/#deployment-v1beta1-apps).
### Configure initializers on the fly ### Configure initializers on the fly
You can configure what initializers are enabled and what resources are subject You can configure what initializers are enabled and what resources are subject
to the initializers by creating `initializerconfigurations`. to the initializers by creating `initializerConfiguration` resources.
You should first deploy the initializer controller and make sure that it is You should first deploy the initializer controller and make sure that it is
working properly before creating the `initializerconfigurations`. Otherwise, any working properly before creating the `initializerConfiguration`. Otherwise, any
newly created resources will be stuck in an uninitialized state. newly created resources will be stuck in an uninitialized state.
The following is an example `initiallizerConfiguration`. The following is an example `initializerConfiguration`:
```yaml ```yaml
apiVersion: admissionregistration.k8s.io/v1alpha1 apiVersion: admissionregistration.k8s.io/v1alpha1
@@ -126,12 +126,16 @@ initializers:
- pods - 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 stuck uninitialized.
Make sure that all expansions of the `<apiGroup, apiVersions, resources>` tuple 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`. in a `rule` are valid. If they are not, separate them in different `rules`.
After you create the `initializerConfiguration`, the system will take a few
seconds to honor the new configuration.
## External Admission Webhooks ## External Admission Webhooks
### What are external admission webhooks? ### What are external admission webhooks?
@@ -232,7 +236,7 @@ it is working properly before creating the externaladmissionhookconfigurations.
Otherwise, depending whether the webhook is configured as fail open or fail Otherwise, depending whether the webhook is configured as fail open or fail
closed, operations will be unconditionally accepted or rejected. closed, operations will be unconditionally accepted or rejected.
The following is an example externaladmissionhookconfiguration. The following is an example `externaladmissionhookconfiguration`:
```yaml ```yaml
apiVersion: admissionregistration.k8s.io/v1alpha1 apiVersion: admissionregistration.k8s.io/v1alpha1