OSDOCS#5338: Scale down data plane to zero

Author: xenolinux

hosted_control_planes/hcp-managing.adoc

@@ -18,5 +18,5 @@ include::modules/hosted-control-planes-pause-reconciliation.adoc[leveloffset=+1]
 //using service-level DNS for control plane services
 include::modules/hosted-control-planes-metrics-sets.adoc[leveloffset=+1]
 //automated machine management
+include::modules/scale-down-data-plane.adoc[leveloffset=+1]
 include::modules/delete-hosted-cluster.adoc[leveloffset=+1]
-

modules/scale-down-data-plane.adoc

@@ -0,0 +1,90 @@
+// Module included in the following assemblies:
+//
+// * hosted_control_planes/hcp-managing.adoc
+
+:_content-type: PROCEDURE
+[id="scale-down-data-plane_{context}"]
+= Scaling down the data plane to zero
+
+If you are not using the hosted control plane, to save the resources and cost you can scale down a data plane to zero.
+
+[NOTE]
+====
+Ensure you are prepared to scale down the data plane to zero. Because the workload from the worker nodes disappears after scaling down.
+====
+
+.Procedure
+
+. Set the `kubeconfig` file to access the hosted cluster by running the following command:
++
+[source,terminal]
+----
+$ export KUBECONFIG=<install_directory>/auth/kubeconfig
+----
+
+. Get the name of the `NodePool` resource associated to your hosted cluster by running the following command:
++
+[source,terminal]
+----
+$ oc get nodepool --namespace <HOSTED_CLUSTER_NAMESPACE>
+----
+
+. Optional: To prevent the pods from draining, add the `nodeDrainTimeout` field in the `NodePool` resource by running the following command:
++
+[source,terminal]
+----
+$ oc edit NodePool <nodepool> -o yaml --namespace <HOSTED_CLUSTER_NAMESPACE>
+----
++
+.Example output
+[source,yaml]
+----
+apiVersion: hypershift.openshift.io/v1alpha1
+kind: NodePool
+metadata:
+# ...
+  name: nodepool-1
+  namespace: clusters
+# ...
+spec:
+  arch: amd64
+  clusterName: clustername <1>
+  management:
+    autoRepair: false
+    replace:
+      rollingUpdate:
+        maxSurge: 1
+        maxUnavailable: 0
+      strategy: RollingUpdate
+    upgradeType: Replace
+  nodeDrainTimeout: 0s <2>
+# ...  
+----
+<1> Defines the name of your hosted cluster.
+<2> Specifies the total amount of time that the controller spends to drain a node. By default, the `nodeDrainTimeout: 0s` setting blocks the node draining process.
++
+[NOTE]
+====
+To allow the node draining process to continue for a certain period of time, you can set the value of the `nodeDrainTimeout` field accordingly, for example, `nodeDrainTimeout: 1m`.
+====
+
+. Scale down the `NodePool` resource associated to your hosted cluster by running the following command:
++
+[source,terminal]
+----
+$ oc scale nodepool/<NODEPOOL_NAME> --namespace <HOSTED_CLUSTER_NAMESPACE> --replicas=0
+----
++
+[NOTE]
+====
+After scaling down the data plan to zero, some pods in the control plane stay in the `Pending` status and the hosted control plane stays up and running. If necessary, you can scale up the `NodePool` resource.
+====
+
+. Optional: Scale up the `NodePool` resource associated to your hosted cluster by running the following command:
++
+[source,terminal]
+----
+$ oc scale nodepool/<NODEPOOL_NAME> --namespace <HOSTED_CLUSTER_NAMESPACE> --replicas=1
+----
++
+After rescaling the `NodePool` resource,  wait for couple of minutes for the `NodePool` resource to become available in a `Ready` state.