How to Export Variables from .env File and Access Them without Python-dotenv

Learn how to correctly export environment variables from a .env file and access them in your Python script without using the python-dotenv module.
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Understanding the Need for Environment Variables in Python

When developing Python applications, you often need to manage configurations and secrets like API keys and database passwords. A common approach is to use environment variables through a .env file. This file allows you to keep sensitive information separate from your codebase. However, you might run into issues when trying to access these variables, especially if you are not using a library like python-dotenv.

In this guide, we will explore a scenario where users encounter problems while attempting to export and access environment variables defined in a .env file. Specifically, we will address why variables do not seem to be recognized in a Python script after being sourced, and clarify how to properly set this up.

The Problem

Consider the following situation:

You create a .env file with the following content:

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After sourcing the .env file and running the script, you get unexpected results:

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Solution Explained

The Key Mistake: Misunderstanding .env Files

Source vs. Export:

The primary issue is that source is used to read and execute commands from a file in the current shell, but it does not export the variables correctly for child processes, such as when you run the Python script.

Variables defined in a sourced file do not automatically become accessible in new environments. They are only defined in the shell that sourced the file.

The Correct Approach

Auto-exporting Variables:

One way to work around this is to employ the -a option while using set:

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This step ensures that all variables defined in the .env file are exported automatically, making them accessible in the Python script.

Why .env Files Are Not Shell Scripts:

It's crucial to remember that .env files are not shell scripts and the rules around quoting can differ. For example:

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This demonstrates that sourcing the file executes the command echo, which ignores the value of TEST set only for that specific environment.

Using dotenv module

Using Python-dotenv:

If you use the python-dotenv library, it processes the .env file correctly and loads the variables into the environment at runtime. An example would be:

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This method avoids sourcing issues and ensures your environment variables are correctly available to your script.

Conclusion

In summary, managing environment variables through a .env file can be tricky if not done correctly. Avoid using source for .env files since they are not shell scripts, and if auto-exporting does not meet your needs, consider using the python-dotenv module. This will ensure that you have a smooth experience when it comes to accessing your environment variables in Python.

By understanding the differences in how environment variables are established and accessed, you can streamline your development process and improve your application's security.