Handling SIGTERM in Gunicorn

Example of how to handle signals of termination with a custom Gunicorn worker.

Article

This is a repository was made as reference for the article in my blog:

• Handling SIGTERM in Gunicorn

Setup

With docker-compose

• Build with docker-compose build
• Start the API with docker-compose up

Just Gunicorn and Python

You can run Gunicorn locally, just make sure that:

• Use a recent Python, it was tested with 3.10
• Create a virtual environment
• Install the requirements.txt
• Run gunicorn command
  • Check Dockerfile for an example of how to call gunicorn
• You will have to send Gunicorn a signal manually like:

kill -TERM <Gunicorn PID>

The gunicorn PID can be obtained with ps aux | grep gunicorn

Testing

You can run service_a_client.py(which depends on requests) or service_a_client.sh(which depends on cURL)

• Run the client application (It will hang on)
• Cancel the docker-compose with CTRL+C for gracefully termination (or kill gunicorn like mentioned above)
• Check that the client received a HTTP 200 and a custom reason from the API

How to set a custom Gunicorn worker

Use the -k parameter and point to the worker path.module.class.

Example:

gunicorn -b 0.0.0.0:8080 --timeout 7200 -w 6 -k service_b.worker.CustomWorker service_b.app:app

License

Apache 2.0