Stdout redirect in configure_logging

scrapy/utils/log.py

@@ -72,6 +72,9 @@ def configure_logging(settings=None):
     if settings:
         logging.root.setLevel(logging.NOTSET)
 
+        if settings.getbool('LOG_STDOUT'):
+            sys.stdout = StreamLogger(logging.getLogger('stdout'))
+
         # Set up the default log handler
         filename = settings.get('LOG_FILE')
         if filename:
@@ -102,6 +105,22 @@ def log_scrapy_info(settings):
     logger.info("Overridden settings: %(settings)r", {'settings': d})
 
 
+class StreamLogger(object):
+    """Fake file-like stream object that redirects writes to a logger instance
+
+    Taken from:
+        http://www.electricmonk.nl/log/2011/08/14/redirect-stdout-and-stderr-to-a-logger-in-python/
+    """
+    def __init__(self, logger, log_level=logging.INFO):
+        self.logger = logger
+        self.log_level = log_level
+        self.linebuf = ''
+
+    def write(self, buf):
+        for line in buf.rstrip().splitlines():
+            self.logger.log(self.log_level, line.rstrip())
+
+
 class LogCounterHandler(logging.Handler):
     """Record log levels count into a crawler stats"""
 

tests/test_utils_log.py

@@ -1,12 +1,14 @@
 # -*- coding: utf-8 -*-
+from __future__ import print_function
 import os
+import sys
 import logging
 import unittest
 
 from testfixtures import LogCapture
 from twisted.python.failure import Failure
 
-from scrapy.utils.log import FailureFormatter, LogCounterHandler
+from scrapy.utils.log import FailureFormatter, LogCounterHandler, StreamLogger
 from scrapy.utils.test import get_crawler
 
 
@@ -75,3 +77,20 @@ class LogCounterHandlerTest(unittest.TestCase):
     def test_filtered_out_level(self):
         self.logger.debug('test log msg')
         self.assertIsNone(self.crawler.stats.get_value('log_count/INFO'))
+
+
+class StreamLoggerTest(unittest.TestCase):
+
+    def setUp(self):
+        self.stdout = sys.stdout
+        logger = logging.getLogger('test')
+        logger.setLevel(logging.WARNING)
+        sys.stdout = StreamLogger(logger, logging.ERROR)
+
+    def tearDown(self):
+        sys.stdout = self.stdout
+
+    def test_redirect(self):
+        with LogCapture() as l:
+            print('test log msg')
+        l.check(('test', 'ERROR', 'test log msg'))