Adding Osha description and enhancing templates

Fixing some template issues and adding osha description and how it works

Change-Id: I870b6669c3bec9f5f9d20b46de26463a216def42

README.rst

@@ -1,13 +1,40 @@
-Openstack Compute High Availability
+==================
+OSHA
+==================
 
-Osha allows Openstack to have High availability in compute nodes. Simply it monitors all compute nodes in your deployment
-and if there is any failure in one of the computes it launches the evacuation tool to evacuate this node and move all
-instances to another compute node.
+Osha, Openstack Compute node High Available provides compute node high availability for OpenStack.
+Simply Osha monitors all compute nodes running in a cloud deployment and if there is any failure
+in one of the compute nodes osha will fence this compute node then osha will try to evacuate all
+running instances on this compute node, finally Osha will notify all users who have workload/instances
+running on this compute node as well as will notify the cloud administrators.
 
-Osha has a plugable architecture so you can use any monitoring system you want to use it for monitoring your compute nodes
-just by adding a simple plugin and adjust your configuration file to use this plugin or combination of plugins if you want
+Osha has a pluggable architecture so it can be used with:
 
-Osha runs as scheduler in the control plane which communicates with the monitoring system to get compute nodes status
+1. Any monitoring system to monitor the compute nodes (currently we support only native openstack services status)
+2. Any fencing driver (currently supports IPMI, libvirt, ...)
+3. Any evacuation driver (currently supports evacuate api call, may be migrate ??)
+4. Any notification system (currently supports email based notifications, ...)
+
+just by adding a simple plugin and adjust the configuration file to use this
+plugin or in future a combination of plugins if required
+
+Osha should run in the control plane, however the architecture supports different scenarios.
 For running osha under high availability mode, it should run with active passive mode.
 
 
+-----------------
+How it works
+-----------------
+
+Starting Osha
+1. Osha Monitoring manager is going to load the required monitoring driver according to the configuration
+2. Osha will query the monitoring system to check if it considers any compute nodes to be down ?
+3.1. if no, Osha will exit displaying No failed nodes
+3.2. if yes, Osha will call the fencing manager to fence the failed compute node
+4. Fencing manager will load the correct fencer according to the configuration
+5. once the compute node is fenced and is powered off now we will start the evacuation process
+6. Osha will load the correct evacuation driver
+7. Osha will evacuate all instances to another computes
+8. Once the evacuation process completed, Osha will call the notification manager
+9. The notification manager will load the correct driver based on the configurations
+10. Osha will start the notification process ...

etc/templates/error.jinja

@@ -10,7 +10,8 @@
 
 <div id="content">
   <p>Dear Administrators, <br />
-      An compute node went down and Osha DID NOT successfully evacuate. Please, find the following details about the host: <br />
+      A compute node failed and Osha DID NOT successfully evacuate.
+      Please, find the following details about the host: <br />
       Host: {{ host }} <br />
       <p>
       Tenants:

etc/templates/success.jinja

@@ -10,7 +10,9 @@
 
 <div id="content">
   <p>Dear Administrators, <br />
-      An compute node went down and Osha did successfully evacuate all instances successfully. Please, find the following details about the evacuated host: <br />
+      A compute node failed and Osha successfully evacuated all instances running
+      on this compute node another computes. Please, find the following details
+      about the evacuated host: <br />
       Host: {{ host }} <br />
       <p>
       Tenants: