Why I have to use python-dotenv in order to load env variables to Python?

Question

I am trying to read in a python script some variables that I have in an environment file myfile.env:

LOCALHOST='1'

If in my python script I just run:

import os
print(os.environ)

It prints:

environ({'PATH': '....', 'HOSTNAME': '...', 'PYCHARM_HOSTED': '1', 'PYTHONUNBUFFERED': '1'})

But in these array I don't have the LOCALHOST variable. I found that I can use python-dotenv and now I see it and working, but I don't get why I have to use it, and it's not feasible to load them only using os module.

Ture Pålsson · Accepted Answer · 2022-04-05 17:32:06Z

2

Because a .env file is not the environment.

os.environ gets data from the environment which, somewhat oversimplified, is a string-to-string (name-to-value) mapping maintained by the operating system for each process, and inherited by child processes. Things are typically put there using export statements in a shell – they will then be inherited by all processes started from that shell — but there are other ways.

.env files are an application-level thing; the operating system does not know about them and they are not automatically loaded into the environment (and hence not picked up by os.environ). That is what python-dotenv takes care of for you.

answered Apr 5, 2022 at 17:32

Ture Pålsson

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1 Comment

mrc Over a year ago

Great thanks, and using docker, and setting env_file parameter doesnt load that file to the os.environment?

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