Loads environment variables from a .envrc or .env file into os.environ. Also useful to load .env environment variables into PyCharm's Python Console

env_loader.py

# Loads environment variables from a .envrc or .env file into os.environ
# Also useful to load .env environment variables into PyCharm's Python Console
# Usage: Download this file into your project's directory and add the following snippet
# to the Python Console's Starting Script.
# Settings > Build, Execution, Deployment > Console > Python Console > Starting script
# ```
# from env_loader import load
# load(".env")
# del load
# ```
# Alternatively, you can add the snippet directly to the Starting Script, but you will
# have to `del` all the variables created by the snippet afterward.
import os
import re

# REGEX_ENVIRONMENT_VARIABLES matches lines that set environment variables
REGEX_ENVIRONMENT_VARIABLES = re.compile(r"^(?:export)?\s+(\w+)=(.*)$")
# REGEX_INTERPOLATION matches values with interpolations in the form ${VAR}
REGEX_INTERPOLATION = re.compile(r"(\$\{(\w+)\})")


def load(filepath: str, echo: bool = False):
    with open(filepath, "r") as the_file:
        for line in the_file:
            match = REGEX_ENVIRONMENT_VARIABLES.match(line)
            if match:
                key, value = match.groups()
                value = value.strip("\"'")
                interpolations = REGEX_INTERPOLATION.findall(value)
                for interpolation_match, interpolation_key in interpolations:
                    if interpolation_key not in os.environ:
                        raise Exception(
                            f"Variable {interpolation_key} is used, but not defined"
                        )
                    value = value.replace(
                        interpolation_match, os.environ[interpolation_key]
                    )
                if echo:
                    print(f"{key}={value}")
                os.environ[key] = value