Django check at runtime if code is executed under "runserver command" or not

Question

I've got a project based on django, that wraps some custom code.

During import, this code is loading some heavy file to be executed. I need to check whether imports are executed under "runserver command" or not. This way I can prevent loading heavy files during django installation.

How can I check if code is executed under runserver command?

Edit/UPDATE:

Unlike this question: How can I tell whether my Django application is running on development server or not?, I don't need to know whether the server is in debug or production mode.

I need to "discriminate" some "imports" based on whether the command below

python manage.py <COMMAND>

is runserver or not, regardless of whether it's debug or production mode.

Why not just set an environment variable and check that way? So MY_VAR=1 python manage.py runserver, then you can use sys.environ('MY_VAR) == '1'? — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Nov 10 at 9:56
You'd probably be better off fixing the actual issue: you shouldn't do significant work when a file is imported, move the actual loading and computation inside some sort of function that you can call as needed. This will also be a problem for you in scenarios like unit testing, where you need the code available and may or may not want the expensive object load. — David Maze
– David Maze, Commented Nov 10 at 10:37
David, yes I agree, but in the project we use external library that by default has initialization with heavy files. — Domenico Monaco
– Domenico Monaco, Commented Nov 13 at 8:39
This question is similar to: How can I tell whether my Django application is running on development server or not?. If you believe it’s different, please edit the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem. — Vegard
– Vegard, Commented Nov 14 at 16:51
The linked question is not about debug or production mode, and most of the answers there directly answer the question of detecting whether the server is operating under runserver and/or doing conditional work based on that result, for example this one. — Vegard
– Vegard, Commented yesterday

willeM_ Van Onsem · Accepted Answer · 2025-11-13 13:25:42Z

1

You can probably hack this into the handle of the runserver command, through monkey patching, i.e.:

# bad idea!!

GLOBAL_VAR = {
  'AS_RUNSERVER': False,
}

from django.core.management.commands.runserver import Command

old_handle = Command.handle
def new_handle(self, *args, **kwargs):
    GLOBAL_VAR['AS_RUNSERVER'] = True
    old_hande(self, *args, **kwargs)
Command.handle = new_handle

but I would advise to make this more clean, and work with an environment variable, like:

import sys

if os.environ.get('ENV_AS_RUN_SERVER') == '1':
    # ...

and then run this with:

ENV_AS_RUN_SERVER=1 python manage.py runserver

edited Nov 13 at 13:25

answered Nov 10 at 10:02

willeM_ Van Onsem

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DragonBobZ · Accepted Answer · 2025-11-10 14:51:57Z

You can override the runserver command to do whatever you want, it's a normal management command.

# your_app/management/commands/runserver.py
from django.conf import settings

from django.contrib.staticfiles.management.commands.runserver import Command as RunserverCommand

class Command(RunserverCommand):
    def add_arguments(self, parser):
        super().handle(self, parser)
        # you can add additional arguments here, maybe to decide whether you
        # should load your file or not

    def handle(self, *args, **kwargs):
        . . .
        # do special things here
        . . .
        super().handle(*args, **kwargs)

But you need to make sure the app housing this management command is installed before django.contrib.staticfiles in your INSTALLED_APPS setting.

INSTALLED_APPS = [
  . . .
  'your_app',
  . . .
  # load this after your_app so custom runserver command loads first
  'django.contrib.staticfiles',
]

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