Debugging Cinder pods

This patch adds info about debugging following cinder service pods.

* cinder-api
* cinder-scheduler
* cinder-volume
* cinder-backup

docs/debugging.md

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+# Debugging Cinder Services
+
+Debugging services is a really important aspect of fixing issues with
+minimal downtime. It is really useful when trying to find and
+fix issues if something breaks in the deployment. We will be using
+``oc debug`` command for debugging Cinder pods. You can find more info
+about ``oc debug`` [here](https://www.redhat.com/sysadmin/how-oc-debug-works)
+and about ``kubectl debug``
+[here](https://kubernetes.io/docs/reference/kubectl/generated/kubectl_debug/).
+
+## Cinder API
+
+##### NOTE: Make sure that ``cinder-api`` statefulset has one replica count.
+
+To start debugging the Cinder API service, we will first list it's
+statefulset.
+
+``oc get statefulset -l component=cinder-api``
+
+Start the debug pod and keep labels to notify loadbalancer to redirect requests
+
+``oc debug statefulset/cinder-api --keep-labels``
+
+Unlabel the original cinder-api pod to stop it from being selected by
+loadbalancer
+
+``oc label pod cinder-api-0 component-``
+
+``oc label pod cinder-api-0 service-``
+
+#### REVERT
+
+After debug pod is removed (exited), label the cinder-api service pod again
+
+``oc label pods cinder-api-0 compoent=cinder-api``
+
+``oc label pods cinder-api-0 service=cinder``
+
+## Cinder Scheduler
+
+To debug the Cinder Scheduler service, you need to first start the debug pod
+
+``oc debug statefulset/cinder-scheduler``
+
+Set the replicas of cinderScheduler pod to 0.
+
+``oc edit oscp``
+
+```
+cinderScheduler:
+  replicas: 0
+```
+
+#### REVERT
+
+After exiting the debug pod, set the replicas again to 1.
+
+```
+cinderScheduler:
+  replicas: 1
+```
+
+## Cinder Volume
+
+To debug the Cinder Volume service, you need to first start the debug pod
+
+``oc debug statefulset/cinder-volume-ceph``
+
+Set the replicas of cinderVolume pod to 0.
+
+``oc edit oscp``
+
+```
+cinderVolume:
+  ceph:
+    replicas: 0
+```
+
+#### REVERT
+
+After exiting the debug pod, set the replicas again to 1.
+
+```
+cinderVolume:
+  ceph:
+    replicas: 1
+```
+
+## Cinder Backup
+
+To debug the Cinder Backup service, you need to first start the debug pod
+
+``oc debug statefulset/cinder-backup``
+
+Set the replicas of cinderBackup pod to 0.
+
+``oc edit oscp``
+
+```
+cinderBackup:
+  replicas: 0
+```
+
+#### REVERT
+
+After exiting the debug pod, set the replicas again to 1.
+
+```
+cinderBackup:
+  replicas: 1
+```