Added a section for day2 operator for azure disk encryption sets.

Author: subhtk

installing/installing_azure/enabling-user-managed-encryption-azure.adoc

@@ -10,6 +10,8 @@ In {product-title} version {product-version}, you can install a cluster with a u
 
 include::modules/installation-azure-preparing-diskencryptionsets.adoc[leveloffset=+1]
 
+include::modules/installation-azure-day2-operations-diskencryptionsets.adoc[leveloffset=+1]
+
 [id="enabling-disk-encryption-sets-azure-next-steps"]
 == Next steps
 

modules/installation-azure-day2-operations-diskencryptionsets.adoc

@@ -0,0 +1,70 @@
+//Module included in the following assemblies:
+//
+// * installing/installing_azure/enabling-disk-encryption-sets-azure.adoc
+
+:_mod-docs-content-type: PROCEDURE
+[id="preparing-disk-encryption-sets-day2-operator"]
+= Preparing an Azure Disk Encryption Set for Day2 operator
+The {product-title} installer can use an existing Disk Encryption Set with a user-managed key. To enable this feature, you can create a Disk Encryption Set in Azure and provide the key to the installer. 
+
+.Prerequisite
+
+* To enable encryption at host by using system managed key during the installation, set the following fields in `install-config.yaml`:
+
+.Procedure
+
+. Mark the node from the `encyptionATHost` cluster resource group as unschedulable using the following command:
++
+[source,terminal]
+----
+$ oc adm cordon <node_name>
+----
+
+. Drain the node to safely evacuate running pods:
++
+[source,terminal]
+----
+$ oc adm drain <node_name> --ignore-daemonsets --delete-emptydir-data
+----
+
+. De-allocate the node using the following command:
++
+[source,terminal]
+----
+$ az vm deallocate -n <node_name> -g <cluster_resource_group>
+----
+
+. Set the `encryptionAtHost` property to `true` using the following command:
++
+[source,terminal]
+----
+$ az vm update -n <node_name> -g <cluster_resource_group> --set securityProfile.encryptionAtHost=true
+----
+
+. Start the node by running the following commands:
++
+[source,terminal]
+----
+$ az vm start -n <node_name> -g <cluster_resource_group>
+----
+
+. Mark the node as schedulable using the follwoing command:
++
+[source,terminal]
+----
+$ oc adm uncordon <node_name>
+----
+
+. Make sure that all the operators are available.
+
+. Repeat the above steps on all the nodes of the `encryptionAtHost`.
+
+[NOTE]
+====
+If you want to enable encryption at host during installation, set the following fields in the `install-config.yaml` file:
+
+* `compute.platform.azure.encryptionAtHost`
+* `controlPlane.platform.azure.encryptionAtHost`
+* `platform.azure.defaultMachinePlatform.encryptionAtHost`
+
+====