Python

Railpack builds and deploys Python applications with support for various package managers and dependency management tools.

Detection

Your project will be detected as a Python application if any of these conditions are met:

• A main.py file exists in the root directory
• A requirements.txt file exists
• A pyproject.toml file exists
• A Pipfile exists

Versions

The Python version is determined in the following order:

• Set via the RAILPACK_PYTHON_VERSION environment variable
• Read from the .python-version file
• Read from the runtime.txt file
• Read from the Pipfile if present
• Defaults to 3.13.2

Runtime Variables

These variables are available at runtime:

PYTHONFAULTHANDLER=1
PYTHONUNBUFFERED=1
PYTHONHASHSEED=random
PYTHONDONTWRITEBYTECODE=1
PIP_DISABLE_PIP_VERSION_CHECK=1
PIP_DEFAULT_TIMEOUT=100

Configuration

Railpack builds your Python application based on your project structure. The build process:

• Installs Python and required system dependencies
• Installs project dependencies using your preferred package manager
• Configures the Python environment for production

The start command is determined by:

1. Framework specific start command (see below)
2. main.py file in the root directory

Package Managers

Railpack supports multiple Python package managers:

• pip - Uses requirements.txt for dependencies
• poetry - Uses pyproject.toml and poetry.lock
• pdm - Uses pyproject.toml and pdm.lock
• uv - Uses pyproject.toml and uv.lock
• pipenv - Uses Pipfile

Config Variables

Variable	Description	Example
RAILPACK_PYTHON_VERSION	Override the Python version	3.11
RAILPACK_DJANGO_APP_NAME	Django app name	myapp.wsgi

System Dependencies

Railpack installs system dependencies for common Python packages:

• pdf2image: Installs poppler-utils
• pydub: Installs ffmpeg
• pymovie: Installs ffmpeg, qt5-qmake, and related Qt packages

Framework Support

Railpack detects and configures caches and commands for popular frameworks:

Django

Railpack detects Django projects by:

• Presence of manage.py
• Django being listed as a dependency

The start command is determined by:

1. RAILPACK_DJANGO_APP_NAME environment variable
2. Scanning Python files for WSGI_APPLICATION setting
3. Runs python manage.py migrate && gunicorn {appName}:application

Databases

Railpack automatically installs system dependencies for common databases:

• PostgreSQL: Installs libpq-dev at build time and libpq5 at runtime
• MySQL: Installs default-libmysqlclient-dev at build time and default-mysql-client at runtime