Managing Gunicorn Processes With Supervisor

Last week, I have written a post about gunicorn applications. We started gunicorn manually, and our application worked. Yay!

However, everything is not so great. When (If) the server reboots, gunicorn must be started manually, again. We should find a way to automate this. Actually, there are few ways to accomplish this, such as: init scripts, and supervisord.

Init scripts are more than enough. But they have some drawbacks. They are not so easy to write or maintain. If you have several projects, things get even harder. Supervisord is a relatively easier way for managing multiple gunicorn processes.

Let’s start with installing supervisor:

sudo apt-get install supervisor

Supervisor uses configuration files for applications located in /etc/supervisor/conf.d/ directory. The configuration for our application is below:

[program:hello]
command = gunicorn hello:app
directory = /path/to/hello/
user = username

This is a very basic configuration required to run gunicorn. Since we are using virtualenv, we need to change “command” parameter to use python and gunicorn from our environment instead of global ones.

command = /path/to/virtualenv/bin/python /path/to/virtualenv/bin/gunicorn hello:app

Now we can test, whether our configuration works or does not. Reload supervisor with following commands and start our application. Stop gunicorn if it is running, and start it again with supervisor.

supervisorctl reread
supervisorctl update
supervisorctl start hello

Now gunicorn must be running, you can make sure by visiting page. If server reboots, supervisor starts it. If gunicorn fails, supervisor restarts it. Finally, everything is great!

You can find more information about supervisor configuration parameters in the documentation. You can also read my blog post about restarting and reloading supervisor.

How to Run Flask Applications with Nginx Using Gunicorn

We have recently bought a VPS for İTÜ24, the online newsletter of Istanbul Technical University. The server is running on Ubuntu Server 12.04 operating system. Due to limited memory resources and performance concerns, we preferred to setup nginx as web server.

Our server will serve several web pages and applications developed in various programming languages, such as PHP, Python, Ruby (on Rails). Currently, we have one Python application, which is using Flask framework.

How we run Flask application with nginx, step by step…
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