Add details about metrics to dev guide.

docs/devguide/source/index.rst

@@ -15,8 +15,7 @@ Welcome to the KubeDR Developer Guide!
    ci_builds
    local_builds
    automated_tests
-
-
+   monitoring
 
 Search
 ======

docs/devguide/source/monitoring.rst

@@ -0,0 +1,61 @@
+============
+ Monitoring
+============
+
+Since *KubeDR* is built with `kubebuilder`_ framework, it
+automatically comes with a way to export `Prometheus`_ metrics. In
+fact, `controller runtime`_ exports several metrics dealing with
+internal implementation details but they are only relevant for
+developers. 
+
+*KubeDR* adds several metrics that are of interest to the
+users. For details about these metrics, check the `user guide`_. 
+
+Here are some high level details regarding the implementation and
+testing of metrics sub-system. 
+
+- All metrics are defined in the file ``kubedr/metrics/metrics.go``. 
+
+The metrics end point is protected by RBAC so until we figure out how
+to configure Prometheus in this setting, the feature was tested in the
+following way:
+
+- Remove RBAC by commenting out the line::
+
+     - manager_auth_proxy_patch.yaml 
+
+  and uncommenting the line::
+
+     - manager_prometheus_metrics_patch.yaml
+
+  in the file::
+
+      kubedr/config/default/kustomization.yaml. 
+
+You need to build *KubeDR* after this change. Once *KubeDR* is
+deployed after this change, run the following command to make metrics
+end point accessible on local host:
+
+.. code-block:: bash
+
+  $ kubectl -n kubedr-system port-forward <KUBEDR-CONTROLLER-POD> 8080:8080
+
+Here is an example:
+
+.. code-block:: bash
+
+  $ kubectl -n kubedr-system port-forward kubedr-controller-manager-bd9f4467c-ljblq 8080:8080
+
+Now, the following command will show all the relevant metrics:
+
+.. code-block:: bash
+
+  $ curl -s http://localhost:8080/metrics | grep kubedr_
+
+.. _kubebuilder: https://book.kubebuilder.io/
+.. _Prometheus: https://prometheus.io
+.. _controller runtime: https://github.com/kubernetes-sigs/controller-runtime
+.. _user guide: https://catalogicsoftware.com/clab-docs/kubedr/userguide
+
+
+