ml-jira-2756:Documented monitoring Argo CD instances

Miner update to address merge review.

Author: masauso-lungu

_topic_maps/_topic_map.yml

@@ -1944,6 +1944,8 @@ Topics:
     File: uninstalling-openshift-gitops
   - Name: Setting up a new Argo CD instance
     File: setting-up-argocd-instance
+  - Name: Monitoring Argo CD instances
+    File: monitoring-argo-cd-instances  
   - Name: Using Argo Rollouts for progressive deployment delivery
     File: using-argo-rollouts-for-progressive-deployment-delivery
   - Name: Configuring an OpenShift cluster by deploying an application with cluster configurations

cicd/gitops/monitoring-argo-cd-instances.adoc

@@ -0,0 +1,17 @@
+:_content-type: ASSEMBLY
+[id="monitoring-argo-cd-instances"]
+= Monitoring Argo CD instances
+include::_attributes/common-attributes.adoc[]
+:context: monitoring-argo-cd-instances
+
+toc::[]
+
+By default, the {gitops-title} Operator automatically detects an installed Argo CD instance in your defined namespace, for example, `openshift-gitops`, and connects it to the monitoring stack of the cluster to provide alerts for out-of-sync applications.
+
+.Prerequisites
+* You have access to the cluster with `cluster-admin` privileges.
+* You have access to the {product-title} web console.
+* You have installed the {gitops-title} Operator in your cluster.
+* You have installed an Argo CD application in your defined namespace, for example, `openshift-gitops`.
+
+include::modules/gitops-monitoring-argo-cd-health-using-prometheus-metrics.adoc[leveloffset=+1]

modules/gitops-monitoring-argo-cd-health-using-prometheus-metrics.adoc

@@ -0,0 +1,24 @@
+// Module included in the following assemblies:
+//
+// * cicd/gitops/monitoring-argo-cd-instances.adoc
+
+:_content-type: PROCEDURE
+[id="gitops-monitoring-argo-cd-health-using-promethous-metrics_{context}"]
+= Monitoring Argo CD health using Prometheus metrics
+
+You can monitor the health status of an Argo CD application by running Prometheus metrics queries against it.
+
+.Procedure
+
+. In the *Developer* perspective of the web console, select the namespace where your Argo CD application is installed, and navigate to *Observe* -> *Metrics*.
+. From the *Select query* drop-down list, select *Custom query*.
+. To check the health status of your Argo CD application, enter the Prometheus Query Language (PromQL) query similar to the following example in the *Expression* field:
++
+.Example
+[source, terminal]
+----
+sum(argocd_app_info{dest_namespace=~"<your_defined_namespace>",health_status!=""}) by (health_status) <1>
+----
+<1> Replace the `<your_defined_namespace>` variable with the actual name of your defined namespace, for example `openshift-gitops`.
+
+