Add possibility to set logging source for Horizon

This patch adds HorizonLoggingSource parameter to enable fluentd to tail logs
from Horizon.

To keep consistency with other services the default value is set as single log located
in appropriate log directory, but we also need to enable customer to pass multiple
horizon log files also used by httpd.

Change-Id: I0161e6d9c76424b301e48b73f1d7b4b071af0676

deployment/horizon/horizon-container-puppet.yaml

@@ -137,6 +137,11 @@ parameters:
                  of hashes, and the hashes should have two items each (name, display)
                  containing Keystone domain name and a human-readable description of
                  the domain respectively.
+  HorizonLoggingSource:
+    type: json
+    default:
+      tag: openstack.horizon
+      file: /var/log/containers/horizon/horizon.log
 
 parameter_groups:
 - label: deprecated
@@ -251,6 +256,14 @@ outputs:
           - {}
       ansible_group_vars:
         keystone_enable_member: true
+      service_config_settings:
+        rsyslog:
+          tripleo_logging_sources_horizon:
+            yaql:
+              expression: $.data.sources.flatten()
+              data:
+                sources:
+                  - {get_param: HorizonLoggingSource}
       # BEGIN DOCKER SETTINGS
       puppet_config:
         config_volume: horizon