Deploying a Celery App

Last updated May 14, 2024

You can find the step-by-step deployment guide here.

Application Build
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Hostman uses the following environment when building a Celery application:

  • Python 3.10, 3.11, 3.12, 3.13, or 3.14
  • pip
  • gunicorn
  • System libraries for working with PostgreSQL and MySQL

Hostman will execute the following commands during the build:

apt-get install -y python3 python3-pip gunicorn python3-psycopg2 libpq-dev python-dev default-mysql-client python3-dev default-libmysqlclient-dev python3-mysqldb --fix-missing
pip3 install psycopg2 
ln /usr/bin/python3 /usr/bin/python -sf
ln /usr/bin/pip3 /usr/bin/pip -sf
pip3 install celery

To install dependencies, add the following line to the build command:

pip3 install --upgrade -r requirements.txt

The default start command is:

celery -A tasks worker --loglevel=INFO

Requirements
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  • Make sure the application initialization file is named main.py.
  • Make sure the application is listening on 0.0.0.0 rather than 127.0.0.1; otherwise, external connections will not work.

Troubleshooting
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Deployment fails
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If there are problems with deployment, first check the deployment log. You will be able to determine at what point something went wrong.

Often the problems are related to the start command. Check that everything in your development environment works with gunicorn. Make sure that all modules required to run the application are present in the requirements.txt file.