Collect HAproxy backend state per server

Change-Id: I6d7ede0cb9187a3d0ec99a4dfabf96fea0a634b2

deployment_scripts/puppet/modules/lma_collector/files/collectd/haproxy.py

@@ -240,6 +240,16 @@ class HAProxyPlugin(base.Base):
             if pxname not in backend_server_states:
                 backend_server_states[pxname] = defaultdict(int)
             backend_server_states[pxname][stat['status']] += 1
+            # Emit metric for the backend server
+            yield {
+                'type_instance': 'backend_server',
+                'values': STATUS_MAP[stat['status']],
+                'meta': {
+                    'backend': pxname,
+                    'state': stat['status'].lower(),
+                    'host': stat['svname'],
+                }
+            }
 
         for pxname, states in backend_server_states.iteritems():
             for s in STATUS_MAP.keys():

deployment_scripts/puppet/modules/lma_collector/files/plugins/decoders/collectd.lua

@@ -290,6 +290,9 @@ function process_message ()
                         msg['Fields']['tag_fields'] = { 'frontend' }
                         msg['Fields']['frontend'] = sample['meta']['frontend']
                     end
+                    if sample['meta']['host'] then
+                        msg['Fields']['hostname'] = sample['meta']['host']
+                    end
                 end
             elseif metric_source == 'apache' then
                 metric_name = string.gsub(metric_name, 'apache_', '')

doc/user/source/metrics/haproxy.rst

@@ -81,6 +81,10 @@ back-end server:
 * ``haproxy_backend_servers``, the count of servers grouped by state. This
   metric has an additional ``state`` field that contains the state of the
   back ends (either 'down' or 'up').
+* ``haproxy_backend_server``, the status of the backend server where values
+  ``0`` and ``1`` represent, respectively, ``DOWN`` and ``UP``.  This metric
+  has an additional ``state`` field that contains the state of the backend
+  (either 'down' or 'up').
 * ``haproxy_backend_session_current``, the number of current sessions.
 * ``haproxy_backend_session_total``, the cumulative number of sessions.
 * ``haproxy_backend_status``, the global back-end status where values ``0``