add zabbix roles information

Signed-off-by: siddharthvipul <siddharthvipul1@gmail.com>

docs/monitoring_metrics/zabbix.rst

@@ -0,0 +1,38 @@
+Monitoring / Metrics with Prometheus
+========================
+
+We are using Zabbix 5.0 (lts) server with PostgreSQL database. Starting with manual configuration in a test vm and then automating it for for deployment, Ansible roles `zabbix-server` and `zabbix-agent` are to results of this PoC work.
+Please follow FAQ to see how to access staging deployment of zabbix.
+
+zabbix-server
+-------------
+
+This role is ready at the base level but as the complexity of the monitoring
+increases, more work would be needed. At the current level, it
+
+  * Installs needed packages for server
+  * configure zabbix, apache and PostgreSQL configuration files
+  * configures web UI
+  * configures kerberos authentication
+
+While these basic things are good for POC, they are not ready to be in
+production until we have configured the following
+
+  * add inventory files for groups and users and have zabbix-cli restore those
+    in case of a fresh installation
+  * Network config audit (see common challenges)
+
+zabbix-agent
+------------
+
+This role is ready to be used and existing templates are good to gather basic
+information. Though specific of what kind of common data would be collected
+from all agent nodes needs to be discussed widely and set in template.
+Other than common metrics, one can also export custom metrics using
+zabbix-sender (see FAQ).
+
+
+Common challenges
+-----------------
+Lack of experience in selinux policies and network configuration, we are not
+very confident with those. A veteran sysadmin would be needed audit.