Allow different log level for django.template

Debug log from the django.template is known to be too verbose. Recently
the sample local_settings.py in Horizon repo has been updated to
disable debug log from this module[1].

This change follows that decision and keep the default INFO log level
even when log_level='DEBUG' is set. Users are still able to enable
debug log from this module by setting the new django_template_log_level
parameter.

[1] 85e20a62e2b986f066484147d0a15446d2699559

Related-Bug: #1720893
Change-Id: I9c301db691da4adce1b9f6c40b7a3583e7e8a6f5

manifests/init.pp

@@ -138,6 +138,10 @@
 #    (optional) Log level of django module. This overrides log_level.
 #    Defaults to undef
 #
+#  [*django_template_log_level*]
+#    (optional) Log level of django.template module.
+#    Defaults to 'INFO'
+#
 #  [*syslog_facility*]
 #    (optional) Syslog facility used when syslog log hander is enabled.
 #    Defaults to 'local1'.
@@ -572,6 +576,7 @@ class horizon(
   $log_handlers                        = ['file'],
   $log_level                           = 'INFO',
   $django_log_level                    = undef,
+  $django_template_log_level           = 'INFO',
   $syslog_facility                     = 'local1',
   $help_url                            = 'http://docs.openstack.org',
   $local_settings_template             = 'horizon/local_settings.py.erb',

releasenotes/notes/django_template_log_level-187b891542873d91.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    The new ``horizon::django_template_log_level`` parameter has been added.
+    This parameter controls log level of the ``django.template`` module.

templates/local_settings.py.erb

@@ -846,6 +846,14 @@ LOGGING = {
             'level': '<%= @django_log_level_real %>',
             'propagate': False,
         },
+        # VariableDoesNotExist error in the debug level from django.template
+        # is VERY noisy and it is output even for valid cases,
+        # so set the default log level of django.template to INFO.
+        'django.template': {
+            'handlers': ['console'],
+            'level': '<%= @django_template_log_level %>',
+            'propagate': False,
+        },
         # Logging from django.db.backends is VERY verbose, send to null
         # by default.
         'django.db.backends': {