Logs should go to stderr (#1383)

Currently, we log to stdout, which is contrary to UNIX conventions.
Also, it makes it impossible to redirect normal standard output of commands
like cmsRWSHelper to a file.

Closes #1382.

Author: gollux

cms/log.py

@@ -393,16 +393,16 @@ def process(self, msg: str, kwargs: dict):
 
 
 # Install a shell handler.
-shell_handler = StreamHandler(sys.stdout)
+shell_handler = StreamHandler(sys.stderr)
 shell_handler.setLevel(logging.INFO)
-shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stdout)))
+shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stderr)))
 root_logger.addHandler(shell_handler)
 
 
 def set_detailed_logs(detailed: bool):
     """Set or unset the shell logs to detailed."""
     global shell_handler
-    color = has_color_support(sys.stdout)
+    color = has_color_support(sys.stderr)
     formatter = DetailedFormatter(color) \
         if detailed else CustomFormatter(color)
     shell_handler.setFormatter(formatter)

cmsranking/Logger.py

@@ -243,9 +243,9 @@ def format(self, record):
 root_logger.setLevel(logging.DEBUG)
 
 # Define the stream handler to output on stderr.
-shell_handler = StreamHandler(sys.stdout)
+shell_handler = StreamHandler(sys.stderr)
 shell_handler.setLevel(logging.INFO)
-shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stdout)))
+shell_handler.setFormatter(CustomFormatter(has_color_support(sys.stderr)))
 root_logger.addHandler(shell_handler)