Add option to log to stderr

freqtrade/configuration/arguments.py

@@ -9,7 +9,8 @@ from typing import Any, Dict, List, Optional
 from freqtrade import constants
 from freqtrade.configuration.cli_options import AVAILABLE_CLI_OPTIONS
 
-ARGS_COMMON = ["verbosity", "logfile", "version", "config", "datadir", "user_data_dir"]
+ARGS_COMMON = ["verbosity", "log_to_stderr", "logfile", "version", "config", "datadir",
+               "user_data_dir"]
 
 ARGS_STRATEGY = ["strategy", "strategy_path"]
 

freqtrade/configuration/cli_options.py

@@ -34,6 +34,12 @@ AVAILABLE_CLI_OPTIONS = {
         action='count',
         default=0,
     ),
+    "log_to_stderr": Arg(
+        '-E', '--stderr',
+        help='Force log messages to be printed to stderr instead of stdout.',
+        action='store_true',
+        default=False,
+    ),
     "logfile": Arg(
         '--logfile',
         help='Log to the file specified.',

freqtrade/configuration/configuration.py

@@ -125,6 +125,8 @@ class Configuration:
         # Log level
         config.update({'verbosity': self.args.get("verbosity", 0)})
 
+        config.update({'log_to_stderr': self.args.get("log_to_stderr", False)})
+
         if 'logfile' in self.args and self.args["logfile"]:
             config.update({'logfile': self.args["logfile"]})
 

freqtrade/loggers.py

@@ -33,8 +33,9 @@ def setup_logging(config: Dict[str, Any]) -> None:
     # Log level
     verbosity = config['verbosity']
 
-    # Log to stdout, not stderr
+    # By default, log to stdout, not stderr
-    log_handlers: List[logging.Handler] = [logging.StreamHandler(sys.stdout)]
+    stream = sys.stderr if config['log_to_stderr'] else sys.stdout
+    log_handlers: List[logging.Handler] = [logging.StreamHandler(stream)]
 
     if config.get('logfile'):
         log_handlers.append(RotatingFileHandler(config['logfile'],