can not override environment settings that already have value with a file

[bmoelans]

I have

env = environ.Env(
    DEBUG=(bool, False),
)
ENV_FILE = str(env.path('ENV_FILE', default='/'))
if os.path.isfile(ENV_FILE):
    overrides = {'DATABASE_URL': os.environ.pop('DATABASE_URL', '')}
    env.read_env(env_file=ENV_FILE, **overrides)
else:
    # unset if no file was found
    ENV_FILE = None

Problem is that in my ENV_FILE, I want to set DATABASE_URL that already has a value when reading the ENV_FILE.

But because def read_env(env_file=None, **overrides) uses setdefault(key, str(val)) this value can not be overwritten.

Is it possible to extend def read_env with an extra boolean argument to decide whether or not to override existing environment variables?

[ericpascual]

Got the exact same problem, and it turned me crazy to find why my code was not working.

By the way, the handling of the overrides argument is a bit strange, because the passed values will not override anything at the end of the day if the variable exists already. Maybe the setdefault used there is not intentional and it should have been a set instead.

[fdemmer]

@bmoelans do i understand correctly, that you have an environment variable DATABASE_URL that should take precedent over the same variable set in a file?

if so, you can just read the file without any overriding. read_env() does not overwrite existing environment variables.

the **overrides argument is confusing though... i'm going to create a pr to change that... not sure what the use case or intention was though, as the tests confirm the rather useless behaviour of not overriding anything.

[bmoelans]

Well the reason of the issue is that we use docker containers for development and that certain variables are already set in docker-compose.yml file before launching Django. The reason behind this is that any developer can run the software out of the box.
I could use docker-compose.override.yml or so, but the env-file are more flexible to switch context.

What is the reason behind the fact that you do not allow to override already set settings?

What I did to solve it for now:

overrides = {'DATABASE_URL': os.environ.pop('DATABASE_URL', ''),
                   'DJANGO_SITE_TYPE': os.environ.pop('DJANGO_SITE_TYPE', '')}
env.read_env(env_file=ENV_FILE, **overrides)

[fdemmer]

What is the reason behind the fact that you do not allow to override already set settings?

i have no idea; not my code; just came to use this recently myself :)

my pull request would make your code sample work and override DATABASE_URL and DJANGO_SITE_TYPE.

[kerthcet]

so is there any result?

[kutenai]

The PR adds a new argument -- overwrite=False to read_env. When set to True, then values from the file overwrite any existing values.

I can only see one downside -- if "overrides" had a value named 'overwrite', then it would enable overwrite behavior.

It is unfortunate the the module uses **overrides as it does, since this puts a limit on adding any new keyword arguments.

I would personally like to see read_env deprecated as written, and replaced with a more flexible version, i.e.

def read_env(cls, env_file=None, overwrite=False, overrides=None):
    if overrides is not None:
        # do some overrides here.

[T-101]

Any chance of merging this PR?

[patrickjrm]

+1 for merging PR #191.

The similar python-dotenv project does have an override=True option.

https://github.com/theskumar/python-dotenv#getting-started

[sdementen]

any news on when this PR could be merged ?
I was bitten by a variant of this bug: an .env file containing twice the same variable for which I expected the last definition of the variable to be the final one

[JakeUrban]

I would also like this PR to be merged. I set fake ENV variables in my Dockerfile that I need to override with variables from my .env file.

[dantheman39]

Also would love for this to be merged.

[mpochron]

Simple to load env file to override environments from settings:

overrides = {key: os.environ.pop(key, value) for key, value in os.environ.items()}
environ.Env.read_env(env_file=str(ROOT_DIR.path('.env')), **overrides)

[sergeyklay]

This is resolved in develop branch. Thank you for the report, and for helping us make django-environ better. And I am sorry about the delay.