From c4cdb82a39381fc2f9acd6cc171ea17649947de6 Mon Sep 17 00:00:00 2001
From: Henrik Levkowetz <henrik@levkowetz.com>
Date: Thu, 23 Feb 2017 11:53:31 +0000
Subject: [PATCH] Made the logging settings explicit in ietf/settings.py
 (instead of copying default then modifying), and added enough surrounding
 information to make it possible to read also for people not very familiar
 with Python's intricate logging infrastructure.  To a large extent to
 understand myself how the logging is set up in Django, and where to hook in
 the affirm() function.  - Legacy-Id: 12902

---
 ietf/settings.py | 104 +++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 87 insertions(+), 17 deletions(-)

diff --git a/ietf/settings.py b/ietf/settings.py
index ce526cc01..8720dfa44 100644
--- a/ietf/settings.py
+++ b/ietf/settings.py
@@ -168,11 +168,6 @@ AUTHENTICATION_BACKENDS = ( 'django.contrib.auth.backends.ModelBackend', )
 # ------------------------------------------------------------------------
 # Django/Python Logging Framework Modifications
 
-# enable HTML error emails
-from django.utils.log import DEFAULT_LOGGING
-LOGGING = DEFAULT_LOGGING.copy()
-LOGGING['handlers']['mail_admins']['include_html'] = True
-
 # Filter out "Invalid HTTP_HOST" emails
 # Based on http://www.tiwoc.de/blog/2013/03/django-prevent-email-notification-on-suspiciousoperation/
 from django.core.exceptions import SuspiciousOperation
@@ -182,11 +177,7 @@ def skip_suspicious_operations(record):
         if isinstance(exc_value, SuspiciousOperation):
             return False
     return True
-LOGGING['filters']['skip_suspicious_operations'] = {
-    '()': 'django.utils.log.CallbackFilter',
-    'callback': skip_suspicious_operations,
-}
-LOGGING['handlers']['mail_admins']['filters'] += [ 'skip_suspicious_operations' ]
+
 # Filter out UreadablePostError:
 from django.http import UnreadablePostError
 def skip_unreadable_post(record):
@@ -195,14 +186,93 @@ def skip_unreadable_post(record):
         if isinstance(exc_value, UnreadablePostError):
             return False
     return True
-LOGGING['filters']['skip_unreadable_posts'] = {
-    '()': 'django.utils.log.CallbackFilter',
-    'callback': skip_unreadable_post,
+
+# Copied from DEFAULT_LOGGING as of Django 1.10.5 on 22 Feb 2017, and modified
+# to incorporate html logging, invalid http_host filtering, and more.
+# Changes from the default has comments.
+
+# The Python logging flow is as follows:
+# (see https://docs.python.org/2.7/howto/logging.html#logging-flow)
+#
+#   Init: get a Logger: logger = logging.getLogger(name)
+#
+#   Logging call, e.g. logger.error(level, msg, *args, exc_info=(...), extra={...})
+#   --> Logger (discard if level too low for this logger)
+#       (create log record from level, msg, args, exc_info, extra)
+#       --> Filters (discard if any filter attach to logger rejects record)
+#           --> Handlers (discard if level too low for handler)
+#               --> Filters (discard if any filter attached to handler rejects record)
+#                   --> Formatter (format log record and emit)
+#
+
+LOGGING = {
+    'version': 1,
+    'disable_existing_loggers': False,
+    #
+    'loggers': {
+        'django': {
+            'handlers': ['console', 'mail_admins'],
+            'level': 'INFO',
+        },
+        'django.server': {
+            'handlers': ['django.server'],
+            'level': 'INFO',
+            'propagate': False,
+        },
+    },
+    #
+    # No logger filters
+    #
+    'handlers': {
+        'console': {
+            'level': 'INFO',
+            'filters': ['require_debug_true'],
+            'class': 'logging.StreamHandler',
+        },
+        'django.server': {
+            'level': 'INFO',
+            'class': 'logging.StreamHandler',
+            'formatter': 'django.server',
+        },
+        'mail_admins': {
+            'level': 'ERROR',
+            'filters': [
+                'require_debug_false',
+                'skip_suspicious_operations', # custom
+                'skip_unreadable_posts', # custom
+            ],
+            'class': 'django.utils.log.AdminEmailHandler',
+            'include_html': True,       # non-default
+        }
+    },
+    #
+    # All these are used by handlers
+    'filters': {
+        'require_debug_false': {
+            '()': 'django.utils.log.RequireDebugFalse',
+        },
+        'require_debug_true': {
+            '()': 'django.utils.log.RequireDebugTrue',
+        },
+        # custom filter, function defined above:
+        'skip_suspicious_operations': {
+            '()': 'django.utils.log.CallbackFilter',
+            'callback': skip_suspicious_operations,
+        },
+        # custom filter, function defined above:
+        'skip_unreadable_posts': {
+            '()': 'django.utils.log.CallbackFilter',
+            'callback': skip_unreadable_post,
+        },
+    },
+    # And finally the formatters
+    'formatters': {
+        'django.server': {
+            '()': 'django.utils.log.ServerFormatter',
+            'format': '[%(server_time)s] %(message)s',
+        }
+    },
 }
-LOGGING['handlers']['mail_admins']['filters'] += [ 'skip_unreadable_posts' ]
-
-
-
 
 # End logging
 # ------------------------------------------------------------------------