---
title: "How to Deploy a Celery App | Hostman Docs"
description: "Learn to easily deploy Celery Python apps on Hostman. Study scalable task queue setup and different optimization techniques."
---

> For the complete documentation index for AI agents, see [llms.txt](https://hostman.com/llms.txt).

You can find the step-by-step deployment guide [here](https://hostman.com/docs/app-platform/backend-apps/).

## Application Build

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:

```shell
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:

```shell
pip3 install --upgrade -r requirements.txt
```

The default start command is:

```shell
celery -A tasks worker --loglevel=INFO
```

## Requirements

-   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

### Deployment fails

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.