Generating a properly secure SECRET_KEY in Django

secret-key-gen.py

"""
Two things are wrong with Django's default `SECRET_KEY` system:

1. It is not random but pseudo-random
2. It saves and displays the SECRET_KEY in `settings.py`

This snippet
1. uses `SystemRandom()` instead to generate a random key
2. saves a local `secret.txt`

The result is a random and safely hidden `SECRET_KEY`.
"""
try:
    SECRET_KEY
except NameError:
    SECRET_FILE = os.path.join(PROJECT_PATH, 'secret.txt')
    try:
        SECRET_KEY = open(SECRET_FILE).read().strip()
    except IOError:
        try:
            import random
            SECRET_KEY = ''.join([random.SystemRandom().choice('abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(-_=+)') for i in range(50)])
            secret = file(SECRET_FILE, 'w')
            secret.write(SECRET_KEY)
            secret.close()
        except IOError:
            Exception('Please create a %s file with random characters \
            to generate your secret key!' % SECRET_FILE)

To see a working example, feel free to git clone my pony-forum repo or deploy it on dotCloud.

This is great, but won't work with PaaS providers like Heroku where the file system is ephemeral. In those cases, modifying this gist to save the secret in a environment variable would fix the issue.

May I suggest using string.printable instead of a hardcoded list of printable characters?

I think string printable includes carriage return and tab.

Ok then may I suggest this version instead:

SECRET_KEY = ''.join([random.SystemRandom().choice("{}{}{}".format(string.ascii_letters, string.digits, string.punctuation)) for i in range(50)])

I made a fork that works on a cloud provider like Heroku:

import os

"""
Two things are wrong with Django's default `SECRET_KEY` system:

1. It is not random but pseudo-random
2. It saves and displays the SECRET_KEY in `settings.py`

This snippet gets an environment variable `DJANGO_SECRET_KEY`

The result is a random and safely hidden `SECRET_KEY`.
"""
try:
    SECRET_KEY
except NameError:
    SECRET_FILE = os.path.join(PROJECT_DIR, 'secret.txt')
    try:
        SECRET_KEY = open(SECRET_FILE).read().strip()
    except IOError:
        SECRET_KEY = os.environ.get('DJANGO_SECRET_KEY')

Why does this try to evaluate SECRET_KEY first? It's not defined anywhere.

If you are using this on a server that runs multiple apps as different UIDs, you should think about setting the permissions bits 0600

Here is a one-liner, that will print to the console:

function mk_dj_secret() { python -c "import random,string;print 'SECRET_KEY=\"%s\"'%''.join([random.SystemRandom().choice(\"{}{}{}\".format(string.ascii_letters, string.digits, string.punctuation)) for i in range(63)])" ;}

you can pipe that to an .env file or a settings.py file:

mk_dj_secret  >> ~/secrets/my_app.env

This is what I use when deploying with docker, and I use decouple in my settings.py

For setting SECRET_KEY env var on Heroku in a single line:

heroku config:set SECRET_KEY=$(python -c 'import random; import string; print("".join([random.SystemRandom().choice("{}{}{}".format(string.ascii_letters, string.digits, string.punctuation)) for i in range(50)]))')

@SEJeff: he is using that particular set of characters because that's the one used by the original function get_random_secret_key(). See line 86 on https://github.com/django/django/blob/3c447b108ac70757001171f7a4791f493880bf5b/django/core/management/utils.py

For starters, notice how there are no capital letters in the original set. So that means you can not use string.ascii_letters, but have to use string.ascii_lowercase instead. Then take a look at the part past the integers. There are 14 "punctuation" characters there, while string.punctuation contains 32.

Your suggestion might work, or it might not. I don't know enough about cryptography nor how the SECRET_KEY is used throughout Django. But it's not a drop-in replacement since it will not generate keys containing the same set of characters.

Actually, Django is using the exact same method to derive the secret key as this snippet and has been since at least 2012 https://github.com/django/django/blame/3c447b108ac70757001171f7a4791f493880bf5b/django/utils/crypto.py#L20

Properly escaped:

function django_secret() { python -c "import random,string;print(''.join([random.SystemRandom().choice(\"{}{}{}\".format(string.ascii_letters, string.digits, string.punctuation)) for i in range(63)]).replace('\\'','\\'\"\\'\"\\''))"; }
echo "DJANGO_SECRET_KEY='$(django_secret)'"

Simplest and most accurate way is to just use the function in Django directly:

python manage.py shell -c 'from django.core.management import utils; print(utils.get_random_secret_key())'

Thanks tjps ... using that in my app.

Is secret-key-gen.py intended to be a one-time generator or would you possibly call at boot time to generate new key? I don't use heroku/(ephemeral fs), but maybe that usage would solve that issue too?

...or generating with any method including tjps' suggestion?

[update] One bad side affect to new secret key is credentials are lost and forces re-authentication (if used).

Hi everyone, I'm very interesting to try that in our django project Epitome.

@ndarville, @SEJeff and everyone thank you for writing this code.

The reason I need this is because I am developing a script to automate installation in linux distributions. The problem is that I haven't found a way to automate the creation of a unique secret key.

I know I'm asking for a lot, but if someone could someone create a pull request to our settings.py file with a script that will automatically create a secret key regardless of being in linux or windows and with the user not having to do anything further, I will be extremely grateful. I have tried implementing the code snippets here but with no success.

Please send me a message if you would like to discuss further, I will be happy to hear from you.

in windows python manage.py shell -c "from django.core.management import utils; print(utils.get_random_secret_key())" (nb double not single quotes)

Simplest and most accurate way is to just use the function in Django directly:

python manage.py shell -c 'from django.core.management import utils; print(utils.get_random_secret_key())'

That's great. Thanks a lot for this info @tjps.

This is one of those gists I made a million years ago for myself and then forgot all about that seems to have taken on its own SEO life subsequently. You definitely shouldn't use the original advice at this point. :)

If using Python 3.6+ also consider e.g. secrets.token_urlsafe .

Another form of the one line command is:

$ python -c "from django.core.management.utils import get_random_secret_key; print(get_random_secret_key())"

from https://stackoverflow.com/a/68085559/1959568.

Please note that your local interpreter might only be available through a versioned binary name, like python3, and/or its absolute path, e.g. /usr/lib/python3.