Resolving the ModuleNotFoundError in Composer Airflow

Discover how to fix the `No module named "exchangelib"` error in Composer Airflow by updating your Kubernetes cluster. Learn the best practices for managing custom operators in Airflow.
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How to Fix the No module named "exchangelib" Error in Composer Airflow

If you’re working with Apache Airflow in Google Cloud Composer and have created a custom operator, you might encounter a frustrating issue: the “ModuleNotFoundError: No module named 'exchangelib'”. This error can disrupt your workflow and make deploying your Directed Acyclic Graphs (DAGs) a headache. In this post, we’ll explore the problem and provide a clear, step-by-step solution to help you get your environment back on track.

Understanding the Problem

Here’s a breakdown of the scenario:

Key Points

You created a custom operator with an import statement:

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When you try to run your DAG, you receive the error from the Airflow web server, indicating that the exchangelib module cannot be found.

The error resolves itself only when the import statement is added directly in the DAG file. This behavior can be puzzling and frustrating for developers.

The Solution: Updating the Composer Cluster

After investigating the issue, the most effective solution was to force an update on the Composer cluster by updating the underlying Kubernetes (k8s) cluster. This method has proven to resolve similar module import issues and ensure that all dependencies are properly recognized and utilized.

Steps to Update Your Composer Cluster

Navigate to your Google Cloud Console:

Open the Google Cloud Console in your web browser.

Access the Composer Environment:

Find the Composer section in the navigation menu and select your Composer environment where the DAGs are running.

Update the Composer Environment:

Click on the Edit button at the top of the environment details page.

Scroll to the bottom of the settings and look for the option to update your Kubernetes version.

Change the version if a newer stable release is available. This ensures any underlying issues are resolved and your environment is up-to-date.

Click Save or Update to apply the changes. This may take some time to complete.

Redeploy Your DAG:

Once the update is complete, redeploy your DAG files. Ensure that the import statements are correctly placed in both the operator and the DAG files.

Check the Airflow Web Server:

After redeploying, monitor the Airflow web server logs to verify that there are no import errors related to the exchangelib module.

Conclusion

The ModuleNotFoundError can be a real roadblock when deploying DAGs in Composer Airflow, particularly when it seems like everything is set up correctly. However, by following the steps outlined in this guide and updating your Composer cluster, you can effectively eliminate the issue and streamline your workflow. Remember, keeping your environment updated is crucial in avoiding such pitfalls in the future.

Feel free to share your experiences with similar errors and solutions below! Your insights can help others in the community facing similar challenges.