Auto reloading python Flask app upon code changes
Experience real-time code updates in Flask by enabling debug
setting in app.run()
. This results in an automatic server refresh whenever you save your code:
This setup provides an instantly updated preview of your changes, without the manual hassle of restarting the Flask server.
Detailed set-up guide
Environment variables to kick-start the auto-reload
In Flask, development-friendly features can be toggled ON by setting certain environment variables:
FLASK_APP
: Set to the name of your module entry point:FLASK_ENV
: Set to'development'
to activate development environment features, including auto-reloading:
For Flask 2.2+, make sure the FLASK_DEBUG
environment variable is set to 1
. It's the secret key to unlock debugging and auto-reloading:
Command line magic with flask run
You can also harness the power of flask run
command-line utility to start your application in debug mode, thereby enabling auto-reloading:
Want to explore all options flask run
provides? Run the below command:
Unleash the beast: Werkzeug debugger
The Werkzeug debugger can also serve your debugging and auto-reloading needs. How to enable it:
Automatic .env
loading and uWSGI integration
Auotomating environment loading using python-dotenv
Congure Flask seamlessly by using python-dotenv
to automatically read environment variables from a .env
file:
This reads in your .env
configurations, including FLASK_APP
and FLASK_ENV
, easing Flask's auto-reload functionality.
Nginx + uWSGI: The Super Duo
As your Flask application grows, you may consider integrating Nginx and uWSGI for better performance and congruency with production environments. uWSGI's touch-reload
can be used for auto-reloading triggered by filesystem changes:
Simply touch the specified file to reload:
Automate uWSGI reloads
Consider making a simple script to automate touching the file and trigger uWSGI's reload:
A word of caution for production usage
Remember: Debug mode and auto-reloading are superheroes for local development, but often morph into villains in a production environment due to potential security risks and performance overhead. Ensure these features are not enabled in a live, production environment.
Extending Your Development Workflow
Auto-reloading in front-end development
In addition to app code, template changes are also auto-reloaded. This enhances front-end development by instantaneously reflecting HTML/CSS updates:
Keeping your configurations tidy
Maintain a dedicated settings file to keep track of and organize multiple configurations:
Then, just pump up your app with these settings!
Visual Studio Code: Your debugging companion
You can also integrate Flask with Visual Studio Code for a smoother debugging experience:
- Get the Python extension running.
- Use the integrated terminal to set environment variables.
- Start the auto-reloading Flask server using the terminal.
Now you have your IDE's debugging tools and Flask's auto-reloading working in harmony. Code and debug in a breeze!
References
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