Merge pull request #28290 from shannonxtreme/api-eviction

Add information to API Evictions from Safely Drain a Node

content/en/docs/tasks/administer-cluster/safely-drain-node.md

@@ -23,8 +23,6 @@ This task also assumes that you have met the following prerequisites:
      and have [configured PodDisruptionBudgets](/docs/tasks/run-application/configure-pdb/) for
      applications that need them.
 
-
-
 <!-- steps -->
 
 ## (Optional) Configure a disruption budget {#configure-poddisruptionbudget}
@@ -100,95 +98,12 @@ replicas to fall below the specified budget are blocked.
 
 If you prefer not to use [kubectl drain](/docs/reference/generated/kubectl/kubectl-commands/#drain) (such as
 to avoid calling to an external command, or to get finer control over the pod
-eviction process), you can also programmatically cause evictions using the eviction API.
+eviction process), you can also programmatically cause evictions using the
+eviction API.
 
-You should first be familiar with using [Kubernetes language clients](/docs/tasks/administer-cluster/access-cluster-api/#programmatic-access-to-the-api) to access the API.
-
-The eviction subresource of a
-Pod can be thought of as a kind of policy-controlled DELETE operation on the Pod
-itself. To attempt an eviction (more precisely: to attempt to
-*create* an Eviction), you POST an attempted operation. Here's an example:
-
-{{< tabs name="Eviction_example" >}}
-{{% tab name="policy/v1" %}}
-{{< note >}}
-`policy/v1` Eviction is available in v1.22+. Use `policy/v1beta1` with prior releases.
-{{< /note >}}
-
-```json
-{
-  "apiVersion": "policy/v1",
-  "kind": "Eviction",
-  "metadata": {
-    "name": "quux",
-    "namespace": "default"
-  }
-}
-```
-{{% /tab %}}
-{{% tab name="policy/v1beta1" %}}
-{{< note >}}
-Deprecated in v1.22 in favor of `policy/v1`
-{{< /note >}}
-
-```json
-{
-  "apiVersion": "policy/v1beta1",
-  "kind": "Eviction",
-  "metadata": {
-    "name": "quux",
-    "namespace": "default"
-  }
-}
-```
-{{% /tab %}}
-{{< /tabs >}}
-
-You can attempt an eviction using `curl`:
-
-```bash
-curl -v -H 'Content-type: application/json' https://your-cluster-api-endpoint.example/api/v1/namespaces/default/pods/quux/eviction -d @eviction.json
-```
-
-The API can respond in one of three ways:
-
-- If the eviction is granted, then the Pod is deleted as if you sent
-  a `DELETE` request to the Pod's URL and received back `200 OK`.
-- If the current state of affairs wouldn't allow an eviction by the rules set
-  forth in the budget, you get back `429 Too Many Requests`. This is
-  typically used for generic rate limiting of *any* requests, but here we mean
-  that this request isn't allowed *right now* but it may be allowed later.
-- If there is some kind of misconfiguration; for example multiple PodDisruptionBudgets
-  that refer the same Pod, you get a `500 Internal Server Error` response.
-
-For a given eviction request, there are two cases:
-
-- There is no budget that matches this pod. In this case, the server always
-  returns `200 OK`.
-- There is at least one budget. In this case, any of the three above responses may
- apply.
-
-## Stuck evictions
-
-In some cases, an application may reach a broken state, one where unless you intervene the
-eviction API will never return anything other than 429 or 500.
-
-For example: this can happen if ReplicaSet is creating Pods for your application but
-the replacement Pods do not become `Ready`. You can also see similar symptoms if the
-last Pod evicted has a very long termination grace period.
-
-In this case, there are two potential solutions:
-
-- Abort or pause the automated operation. Investigate the reason for the stuck application,
-  and restart the automation.
-- After a suitably long wait, `DELETE` the Pod from your cluster's control plane, instead
-  of using the eviction API.
-
-Kubernetes does not specify what the behavior should be in this case; it is up to the
-application owners and cluster owners to establish an agreement on behavior in these cases.
+For more information, see [API-initiated eviction](/docs/concepts/scheduling-eviction/api-eviction/).
 
 ## {{% heading "whatsnext" %}}
 
-
 * Follow steps to protect your application by [configuring a Pod Disruption Budget](/docs/tasks/run-application/configure-pdb/).