Redirect output to the logger. Closes #3134.

Redirects:
    - the standard output
    - the standard error
    - the twisted log output
to the logger.

3 files changed, 119 insertions, 20 deletions

diff --git a/changes/feature_3134-redirect-output-to-logger b/changes/feature_3134-redirect-output-to-logger
new file mode 100644
index 00000000..b397c5bc
--- /dev/null
+++ b/changes/feature_3134-redirect-output-to-logger
@@ -0,0 +1 @@
+  o Redirect stdout/stderr and twisted log to the logger. Closes #3134.
diff --git a/src/leap/app.py b/src/leap/app.py
index 0ee78310..c0902efa 100644
--- a/src/leap/app.py
+++ b/src/leap/app.py
@@ -27,6 +27,7 @@ from leap.common.events import server as event_server
 from leap.util import __version__ as VERSION
 from leap.util import leap_argparse
 from leap.util.leap_log_handler import LeapLogHandler
+from leap.util.streamtologger import StreamToLogger
 from leap.util.requirement_checker import check_requirements
 from leap.gui import locale_rc
 from leap.gui import twisted_main
@@ -61,40 +62,85 @@ def install_qtreactor(logger):
     logger.debug("Qt4 reactor installed")
 
 
-def main():
+def add_logger_handlers(debug=False, logfile=None):
     """
-    Starts the main event loop and launches the main window.
+    Create the logger and attach the handlers.
+
+    :param debug: the level of the messages that we should log
+    :type debug: bool
+    :param logfile: the file name of where we should to save the logs
+    :type logfile: str
+    :return: the new logger with the attached handlers.
+    :rtype: logging.Logger
     """
-    event_server.ensure_server(event_server.SERVER_PORT)
-
-    _, opts = leap_argparse.init_leapc_args()
-    debug = opts.debug
-    standalone = opts.standalone
-    bypass_checks = opts.danger
-
     # TODO: get severity from command line args
     if debug:
         level = logging.DEBUG
     else:
         level = logging.WARNING
 
-    # Console logger
+    # Create logger and formatter
     logger = logging.getLogger(name='leap')
     logger.setLevel(level)
-    console = logging.StreamHandler()
-    console.setLevel(level)
     log_format = '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
     formatter = logging.Formatter(log_format)
+
+    # Console handler
+    console = logging.StreamHandler()
+    console.setLevel(level)
     console.setFormatter(formatter)
     logger.addHandler(console)
+    logger.debug('Console handler plugged!')
 
     # LEAP custom handler
     leap_handler = LeapLogHandler()
     leap_handler.setLevel(level)
     logger.addHandler(leap_handler)
-
     logger.debug('Leap handler plugged!')
 
+    # File handler
+    if logfile is not None:
+        logger.debug('Setting logfile to %s ', logfile)
+        fileh = logging.FileHandler(logfile)
+        fileh.setLevel(logging.DEBUG)
+        fileh.setFormatter(formatter)
+        logger.addHandler(fileh)
+        logger.debug('File handler plugged!')
+
+    return logger
+
+
+def replace_stdout_stderr_with_logging(logger):
+    """
+    Replace:
+        - the standard output
+        - the standard error
+        - the twisted log output
+    with a custom one that writes to the logger.
+    """
+    sys.stdout = StreamToLogger(logger, logging.DEBUG)
+    sys.stderr = StreamToLogger(logger, logging.ERROR)
+
+    # Replace twisted's logger to use our custom output.
+    from twisted.python import log
+    log.startLogging(sys.stdout)
+
+
+def main():
+    """
+    Starts the main event loop and launches the main window.
+    """
+    event_server.ensure_server(event_server.SERVER_PORT)
+
+    _, opts = leap_argparse.init_leapc_args()
+    standalone = opts.standalone
+    bypass_checks = opts.danger
+    debug = opts.debug
+    logfile = opts.log_file
+
+    logger = add_logger_handlers(debug, logfile)
+    replace_stdout_stderr_with_logging(logger)
+
     if not we_are_the_one_and_only():
         # leap-client is already running
         logger.warning("Tried to launch more than one instance "
@@ -107,13 +153,6 @@ def main():
     logger.info('~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~')
     logger.info('LEAP client version %s', VERSION)
     logger.info('~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~')
-    logfile = opts.log_file
-    if logfile is not None:
-        logger.debug('Setting logfile to %s ', logfile)
-        fileh = logging.FileHandler(logfile)
-        fileh.setLevel(logging.DEBUG)
-        fileh.setFormatter(formatter)
-        logger.addHandler(fileh)
 
     logger.info('Starting app')
     app = QtGui.QApplication(sys.argv)
diff --git a/src/leap/util/streamtologger.py b/src/leap/util/streamtologger.py
new file mode 100644
index 00000000..25a06718
--- /dev/null
+++ b/src/leap/util/streamtologger.py
@@ -0,0 +1,59 @@
+# -*- coding: utf-8 -*-
+# streamtologger.py
+# Copyright (C) 2013 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Stream object that redirects writes to a logger instance.
+"""
+import logging
+
+
+class StreamToLogger(object):
+    """
+    Fake file-like stream object that redirects writes to a logger instance.
+
+    Credits to:
+    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):
+        """
+        Constructor, defines the logger and level to use to log messages.
+
+        :param logger: logger object to log messages.
+        :type logger: logging.Handler
+        :param log_level: the level to use to log messages through the logger.
+        :type log_level: int
+                        look at logging-levels in 'logging' docs.
+        """
+        self._logger = logger
+        self._log_level = log_level
+
+    def write(self, data):
+        """
+        Simulates the 'write' method in a file object.
+        It writes the data receibed in buf to the logger 'self._logger'.
+
+        :param data: data to write to the 'file'
+        :type data: str
+        """
+        for line in data.rstrip().splitlines():
+            self._logger.log(self._log_level, line.rstrip())
+
+    def flush(self):
+        """
+        Dummy method. Needed to replace the twisted.log output.
+        """
+        pass