Updated documentation for CEILOMETER_BACKEND

- Updated devstackGSG.rst to set CEILOMETER_BACKEND
 - Added CEILOMETER_BACKEND to local.conf.minimal
 - Added a reno for this bug fix

Change-Id: Ibbf606021a1f0dcc0db6c586e092b03df423a7a5
Closes-Bug: #1655611

doc/source/devstackGSG.rst

@@ -36,6 +36,9 @@ from the collectd-ceilometer-plugin repo into your devstack directory.
 
 Edit the "HOST_IP" varible to appropriately match your environment.
 
+Also include your chosen "CEILOMETER_BACKEND", as there is no default backend for
+ceilometer. The options for this backend include mysql,es,postgresql or mongodb.
+
 If you wish to enable any extra features please follow the instructions in the
 "Additional Features" section below before moving on to the next step.
 
@@ -73,4 +76,4 @@ To enable this feature execute the following instructions:
   If you would like to add more than one new unit include them in the same line
   and seperate each meter and its unit with a comma, as shown below.
 
-| COLLECTD_CEILOMETER_UNITS="<meter> <unit>,<meter> <unit>"
+| COLLECTD_CEILOMETER_UNITS="<meter> <unit>,<meter> <unit>"

doc/source/examples/local.conf.minimal

@@ -20,6 +20,10 @@ enable_service rabbit
 enable_service dstat
 
 enable_plugin ceilometer https://github.com/openstack/ceilometer master
+# Ceilometer requires a backend, selected default is mysql.
+# For more options refer to devstackGSG.rst
+CEILOMETER_BACKEND=mysql
+
 enable_plugin collectd-ceilometer https://github.com/openstack/collectd-ceilometer-plugin stable/newton
 
 COLLECTD_INSTALL=True

releasenotes/notes/bug-1655611-2135600015157ed9.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - Fixes 'bug 1655611 https://bugs.launchpad.net/collectd-ceilometer-plugin/+bug/1655611'.
+    Included information on defining the "CEILOMETER_BACKEND", included information on the
+    the backend options in devstackGSG.rst. Added mysql as the backend to the
+    collectd-ceilometer-plugin.conf file. The ceilometer backend has to be defined as
+    there is no longer a default.