Updated plugin doc for Argo CD rollout feature

Author: gtrivedi88

artifacts/rhdh-plugins-reference/argocd/argocd-plugin-admin.adoc

@@ -70,6 +70,143 @@ global:
         disabled: false
 ----
 
+== (Optional) Enabling Argo CD Rollouts feature
+
+The Argo CD Rollouts feature enhances Kubernetes by providing advanced deployment strategies, such as blue-green and canary deployments, for your applications. When integrated into the backstage Kubernetes plugin, it allows developers and operations team to visualize and manage these Rollouts seamlessly within the Backstage interface.
+
+.Prerequisites
+
+* *Backstage Kubernetes plugin installed:* Verify that the @backstage/plugin-kubernetes-backend is installed and configured. Follow the installation guide and configuration guide if needed.
+
+* *Kubernetes cluster access:* Ensure you have access to the Kubernetes cluster with the necessary permissions to create and manage custom resources and `ClusterRoles`.
+
+* *Argo Rollouts resources:* Confirm that the Kubernetes cluster has the `argoproj.io` group resources (for example, Rollouts and AnalysisRuns) installed.
+
+.Procedures
+
+. Update `app-config.yaml` for custom resources.
+
+.. Open the `app-config.yaml` file in your Backstage instance.
+
+.. Add the following `customResources` component under the `kubernetes` configuration to enable Argo Rollouts and AnalysisRuns:
++
+[source,yaml]
+----
+kubernetes:
+  ...
+  customResources:
+    - group: 'argoproj.io'
+      apiVersion: 'v1alpha1'
+      plural: 'Rollouts'
+    - group: 'argoproj.io'
+      apiVersion: 'v1alpha1'
+      plural: 'analysisruns'
+----
+
+. Grant `ClusterRole` permissions for custom resources.
+
+.. Verify whether the Backstage Kubernetes plugin is already configured. If it is, the `ClusterRole` for Rollouts and AnalysisRuns might already be granted.
++
+[NOTE]
+====
+You can use a prepared manifest for a read-only `ClusterRole` that provides access for both the Kubernetes plugin and the ArgoCD plugin.
+====
+
+.. If not already granted, use the following YAML manifest to create the ClusterRole:
++
+[source,yaml]
+----
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: backstage-read-only
+rules:
+  - apiGroups:
+      - argoproj.io
+    resources:
+      - Rollouts
+      - analysisruns
+    verbs:
+      - get
+      - list
+----
+
+.. Apply the manifest to the cluster using `kubectl`:
++
+[source,bash]
+----
+kubectl apply -f <your-clusterrole-file>.yaml
+----
+
+.. Ensure the `ServiceAccount` accessing the cluster has this `ClusterRole` assigned.
+
+. Add annotations to `catalog-info.yaml` to identify Kubernetes resources for Backstage
+
+.. For identifying resources by entity ID:
++
+[source,yaml]
+----
+annotations:
+  ...
+  backstage.io/kubernetes-id: <BACKSTAGE_ENTITY_NAME>
+----
+
+.. For identifying resources by namespace (optional):
++
+[source,yaml]
+----
+annotations:
+  ...
+  backstage.io/kubernetes-namespace: <RESOURCE_NAMESPACE>
+----
+
+.. For using custom label selectors (takes precedence over the above annotations):
++
+[source,yaml]
+----
+annotations:
+  ...
+  backstage.io/kubernetes-label-selector: 'app=my-app,component=front-end'
+----
+
+. Add label to Kubernetes resources to enable Backstage to find the appropriate Kubernetes resources.
+
+.. Backstage Kubernetes plugin label: Add this label to map resources to specific Backstage entities.
++
+[source,yaml]
+----
+labels:
+  ...
+  backstage.io/kubernetes-id: <BACKSTAGE_ENTITY_NAME>
+----
+
+.. GitOps application mapping: Add this label to map Argo CD Rollouts to a specific GitOps application
++
+[source,yaml]
+----
+labels:
+  ...
+  app.kubernetes.io/instance: <GITOPS_APPLICATION_NAME>
+----
+
++
+[NOTE]
+====
+If using the label selector annotation (backstage.io/kubernetes-label-selector), ensure the specified labels are present on the resources. The label selector will override other annotations like kubernetes-id or kubernetes-namespace.
+====
+
+.Verification
+
+. Push code changes to your GitOps repository to trigger a deployment.
+
+. Open the Backstage interface and navigate to the entity you configured.
+
+. Confirm that:
+
+** Kubernetes resources, such as Rollouts and AnalysisRuns, are visible under the *Kubernetes* tab.
+
+** The Argo CD Rollouts feature is functioning as expected, allowing you to monitor rollouts status and manage deployments.
+
 [role="_additional-resources"]
 .Additional resources