Resolving the os.getenv() Confusion: How to Properly Load Environment Variables in Python

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Understanding the Issue: Wrong STAGING_BUCKET Value

The Problem at Hand

Imagine you're working on an Airflow project and recently decided to change the STAGING_BUCKET variable in your .env file from:

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to

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However, despite this change, running your code still returns the old value (diff-staging-bucket). How could this happen?

Existence of Global Variables: When you run env in your terminal, you discover that there is indeed a global environment variable STAGING_BUCKET set to diff-staging-bucket.

The Solution: How to Load Environment Variables Correctly

To resolve this issue, you must understand the distinction between .env files and environment variables set in your system. Below, I outline the necessary steps to ensure that your Python application accesses the correct variables.

What You Need to Know

Environment Variables vs. .env Files

Environment Variables: These are set using commands like export or setenv and can be defined in shell init files (e.g., .bashrc or .profile). When you launch your terminal, these variables come into effect, making them available to any application launched from that terminal.

.env Files: These files are simply a collection of variable definitions, and they do not automatically translate to environment variables recognized by your operating system or Python code. They require specific handling to load them correctly.

Using python-dotenv

To utilize variables defined in your .env file seamlessly, you can use a library called python-dotenv. This library ensures that the environment variables within your .env file are loaded into your environment at runtime.

Step-by-Step Implementation

Install the python-dotenv package:
Run the following command in your terminal:

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Modify your Python script:

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Run Your Project: After making these changes, run your Airflow project again. You should now see our-staging-bucket printed as expected.

Important Considerations

Ensure that your .env file is in the same directory as your Python script or specify the path to it in load_dotenv() if it's located elsewhere.

Remember to restart your terminal or any running instances of your application after you change the .env file to see the effects.

Conclusion

By following the steps outlined above, you'll successfully resolve the issue of incorrect variable values in your projects. Happy coding!