How To Remove Flask Application Warning Message Docker

As a developer who frequently uses Flask and Docker, I understand the importance of removing warning messages that may arise when deploying Flask applications within a Docker environment.

Understanding the Issue

When running a Flask application within a Docker container, you might encounter a warning message that looks something like this:

* Running on (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 123-456-789

This warning message can be distracting and may not be suitable for a production environment. Let’s explore how to remove this message and ensure a cleaner deployment.

Solution: Updating Flask App Configuration

To remove the warning message, we need to update the configuration of the Flask app. By setting the FLASK_ENV and FLASK_DEBUG environment variables, we can control the environment and debug mode of the Flask app respectively.

Here’s an example of setting these environment variables within the Dockerfile:

ENV FLASK_ENV=production

By setting FLASK_ENV to production and FLASK_DEBUG to 0, we can suppress the warning messages and ensure that the Flask app runs in a production-ready configuration.

Building the Docker Image

After updating the Flask app configuration, rebuild the Docker image to apply the changes. This can be done using the docker build command, ensuring that the updated Dockerfile is included in the build context.

Testing the Deployment

Once the Docker image is rebuilt, run the container and access the Flask application. You should no longer see the previous warning message, and the Flask app should be running in a cleaner, production-ready state.


Removing the Flask application warning message in a Docker environment is a crucial step towards achieving a seamless, professional deployment. By updating the Flask app configuration and rebuilding the Docker image, we can ensure that our application runs without unnecessary distractions. This approach not only enhances the user experience but also reflects a commitment to best practices in app deployment.