Added argument to change log format. (#414)

CHANGELOG.txt

@@ -11,6 +11,8 @@ Unreleased
   range of versions does not represent a good use of maintainer time. Going
   forward the latest Twisted version will be required.
 
+* Added `log-fmt` CLI argument.
+
 3.0.2 (2021-04-07)
 ------------------
 

daphne/cli.py

@@ -90,6 +90,11 @@ class CommandLineInterface:
             help="Where to write the access log (- for stdout, the default for verbosity=1)",
             default=None,
         )
+        self.parser.add_argument(
+            "--log-fmt",
+            help="Log format to use",
+            default="%(asctime)-15s %(levelname)-8s %(message)s"
+        )
         self.parser.add_argument(
             "--ping-interval",
             type=int,
@@ -215,7 +220,7 @@ class CommandLineInterface:
                 2: logging.DEBUG,
                 3: logging.DEBUG,  # Also turns on asyncio debug
             }[args.verbosity],
-            format="%(asctime)-15s %(levelname)-8s %(message)s",
+            format=args.log_fmt,
         )
         # If verbosity is 1 or greater, or they told us explicitly, set up access log
         access_log_stream = None