[1.10.x] Fixed #27271 -- Fixed a crash in runserver logging.

Allowed ServerFormatter to handle simple string messages or messages with
formatting arguments. The formatter will set the server_time variable on
the log record if it's required by the format string but wasn't passed in
extra parameters.

Backport of 6709ea4ae9 from master

django/utils/log.py

@@ -164,28 +164,32 @@ class ServerFormatter(logging.Formatter):
         super(ServerFormatter, self).__init__(*args, **kwargs)
 
     def format(self, record):
-        args = record.args
         msg = record.msg
+        status_code = getattr(record, 'status_code', None)
 
-        if len(args) == 0:
-            msg = self.style.HTTP_BAD_REQUEST(msg)
-        else:
-            if args[1][0] == '2':
+        if status_code:
+            if 200 <= status_code < 300:
                 # Put 2XX first, since it should be the common case
                 msg = self.style.HTTP_SUCCESS(msg)
-            elif args[1][0] == '1':
+            elif 100 <= status_code < 200:
                 msg = self.style.HTTP_INFO(msg)
-            elif args[1] == '304':
+            elif status_code == 304:
                 msg = self.style.HTTP_NOT_MODIFIED(msg)
-            elif args[1][0] == '3':
+            elif 300 <= status_code < 400:
                 msg = self.style.HTTP_REDIRECT(msg)
-            elif args[1] == '404':
+            elif status_code == 404:
                 msg = self.style.HTTP_NOT_FOUND(msg)
-            elif args[1][0] == '4':
+            elif 400 <= status_code < 500:
                 msg = self.style.HTTP_BAD_REQUEST(msg)
             else:
-                # Any 5XX, or any other response
+                # Any 5XX, or any other status code
                 msg = self.style.HTTP_SERVER_ERROR(msg)
 
+        if self.uses_server_time() and not hasattr(record, 'server_time'):
+            record.server_time = self.formatTime(record, self.datefmt)
+
         record.msg = msg
         return super(ServerFormatter, self).format(record)
+
+    def uses_server_time(self):
+        return self._fmt.find('%(server_time)') >= 0

docs/releases/1.10.2.txt

@@ -22,3 +22,6 @@ Bugfixes
   ``SplitDateTimeWidget``, ``SelectDateWidget``, and ``SplitArrayWidget``
   (:ticket:`27186`). Custom widgets affected by this issue may need to
   implement a :meth:`~django.forms.Widget.value_omitted_from_data` method.
+
+* Fixed a crash in ``runserver`` logging during a "Broken pipe" error
+  (:ticket:`27271`).

tests/logging_tests/tests.py

@@ -3,19 +3,22 @@ from __future__ import unicode_literals
 
 import logging
 import warnings
+from contextlib import contextmanager
 
 from admin_scripts.tests import AdminScriptTestCase
 
 from django.conf import settings
 from django.core import mail
 from django.core.files.temp import NamedTemporaryFile
+from django.core.management import color
 from django.db import connection
 from django.test import RequestFactory, SimpleTestCase, override_settings
 from django.test.utils import LoggingCaptureMixin, patch_logger
+from django.utils import six
 from django.utils.deprecation import RemovedInNextVersionWarning
 from django.utils.log import (
     DEFAULT_LOGGING, AdminEmailHandler, CallbackFilter, RequireDebugFalse,
-    RequireDebugTrue,
+    RequireDebugTrue, ServerFormatter,
 )
 
 from .logconfig import MyEmailBackend
@@ -513,3 +516,47 @@ class SchemaLoggerTests(SimpleTestCase):
                 }},
             )]
         )
+
+
+class LogFormattersTests(SimpleTestCase):
+
+    def test_server_formatter_styles(self):
+        color_style = color.make_style('')
+        formatter = ServerFormatter()
+        formatter.style = color_style
+        log_msg = 'log message'
+        status_code_styles = [
+            (200, 'HTTP_SUCCESS'),
+            (100, 'HTTP_INFO'),
+            (304, 'HTTP_NOT_MODIFIED'),
+            (300, 'HTTP_REDIRECT'),
+            (404, 'HTTP_NOT_FOUND'),
+            (400, 'HTTP_BAD_REQUEST'),
+            (500, 'HTTP_SERVER_ERROR'),
+        ]
+        for status_code, style in status_code_styles:
+            record = logging.makeLogRecord({'msg': log_msg, 'status_code': status_code})
+            self.assertEqual(formatter.format(record), getattr(color_style, style)(log_msg))
+        record = logging.makeLogRecord({'msg': log_msg})
+        self.assertEqual(formatter.format(record), log_msg)
+
+    def test_server_formatter_default_format(self):
+        server_time = '2016-09-25 10:20:30'
+        log_msg = 'log message'
+        logger = logging.getLogger('django.server')
+
+        @contextmanager
+        def patch_django_server_logger():
+            old_stream = logger.handlers[0].stream
+            new_stream = six.StringIO()
+            logger.handlers[0].stream = new_stream
+            yield new_stream
+            logger.handlers[0].stream = old_stream
+
+        with patch_django_server_logger() as logger_output:
+            logger.info(log_msg, extra={'server_time': server_time})
+            self.assertEqual('[%s] %s\n' % (server_time, log_msg), logger_output.getvalue())
+
+        with patch_django_server_logger() as logger_output:
+            logger.info(log_msg)
+            six.assertRegex(self, logger_output.getvalue(), r'^\[[-:,.\s\d]+\] %s' % log_msg)