Custom arguments' help is not shown when calling locust --help

[fstamour]

Prerequisites

• I am using the latest version of Locust
• I am reporting a bug, not asking a question

Description

(I'm not certain you would consider this a bug or a feature request.)

How to reproduce

1. Create a locust.conf file in the current directory
2. Add custom arguments
3. Run locust --help (or even locust -f locustfile.py)

Expected result

• I expect locust to load the locustfile.py and run the init_command_line_parser hook
• I expect to see my custom arguments' help to be shown in locust --help 's output

Actual result

• The locustfile.py is not loaded at all when running locust --help.
• The custom arguments' help are not shown in locust --help 's output.

Possible fix

Replace the built-in help action by something that loads the locustfile before printing the help.

• Add an explicit --help argument (parser.add_argument('-h', '--help', action="store_true" ...)
• Check if args.help == True
• Call parser.print_help() and parser.exit() (just like the default _HelpAction does)

Command line

locust --help

Locustfile contents

import argparse

from locust import events

print("top-level")


@events.init_command_line_parser.add_listener
def init_command_line_parser(parser: argparse.ArgumentParser):
    """
    Initialize the command line parser with custom arguments.
    """
    print("init_command_line_parser")

    parser.add_argument(
        "--my-little-argument",
        type=str,
        help="Choose a custom load shape",
        choices=["a", "b", "c"],
    )

Python version

Test with both Python 3.10.12 and 3.12.6

Locust version

2.31.6

Operating system

Ubuntu 22.04.4 LTS and 24.04 LTS

[cyberw]

Yea this is a real bug. I think your suggested fix sounds reasonable and would love for you to PR it!

[shubhamsugara22]

@fstamour is anyone working this ? , would like to have a crack at it