Make infinite run time the default when running headless

locust/argument_parser.py

@@ -161,7 +161,7 @@ def setup_parser_arguments(parser):
     parser.add_argument(
         "-t",
         "--run-time",
-        help="Stop after the specified amount of time, e.g. (300s, 20m, 3h, 1h30m, etc.). Only used together with --headless",
+        help="Stop after the specified amount of time, e.g. (300s, 20m, 3h, 1h30m, etc.). Only used together with --headless. Defaults to run forever.",
         env_var="LOCUST_RUN_TIME",
     )
     parser.add_argument(

locust/main.py

@@ -251,15 +251,6 @@ def main():
             logger.error("Valid --run-time formats are: 20, 20s, 3m, 2h, 1h20m, 3h30m10s, etc.")
             sys.exit(1)
 
-        def spawn_run_time_limit_greenlet():
-            logger.info("Run time limit set to %s seconds" % options.run_time)
-
-            def timelimit_stop():
-                logger.info("Time limit reached. Stopping Locust.")
-                runner.quit()
-
-            gevent.spawn_later(options.run_time, timelimit_stop).link_exception(greenlet_exception_handler)
-
     if options.csv_prefix:
         stats_csv_writer = StatsCSVFileWriter(
             environment, stats.PERCENTILES_TO_REPORT, options.csv_prefix, options.stats_history_enabled
@@ -331,8 +322,20 @@ def timelimit_stop():
             else:
                 runner.start(options.num_users, options.spawn_rate)
 
+    def spawn_run_time_limit_greenlet():
+        def timelimit_stop():
+            logger.info("Time limit reached. Stopping Locust.")
+            runner.quit()
+
+        gevent.spawn_later(options.run_time, timelimit_stop).link_exception(greenlet_exception_handler)
+
     if options.run_time:
+        logger.info("Run time limit set to %s seconds" % options.run_time)
         spawn_run_time_limit_greenlet()
+    elif options.headless:
+        logger.info("No run time limit set, use CTRL+C to interrupt.")
+    else:
+        pass  # dont log anything - not having a time limit is normal when not running headless
 
     stats_printer_greenlet = None
     if not options.only_summary and (options.print_stats or (options.headless and not options.worker)):

locust/test/test_main.py

@@ -237,6 +237,22 @@ def test_default_headless_spawn_options(self):
             )
             self.assertIn("Spawning 1 users at the rate 1 users/s", output)
 
+    def test_headless_spawn_options_wo_run_time(self):
+        with mock_locustfile() as mocked:
+            proc = subprocess.Popen(
+                ["locust", "-f", mocked.file_path, "--host", "https://test.com/", "--headless"],
+                stdout=PIPE,
+                stderr=PIPE,
+            )
+            gevent.sleep(1)
+            proc.send_signal(signal.SIGTERM)
+            stdout, stderr = proc.communicate()
+            self.assertEqual(0, proc.returncode)
+            stderr = stderr.decode("utf-8")
+            self.assertIn("Starting Locust", stderr)
+            self.assertIn("No run time limit set, use CTRL+C to interrupt", stderr)
+            self.assertIn("Shutting down (exit code 0), bye", stderr)
+
     def test_default_headless_spawn_options_with_shape(self):
         content = (
             MOCK_LOUCSTFILE_CONTENT