What does Codara need from a Python project?
A dependency file at the root of the repository: requirements.txt, pyproject.toml or a Pipfile. A uv.lock or poetry.lock next to pyproject.toml tells Railpack to install with uv or Poetry. Pin the Python version in a .python-version file.
Your web server must listen on all interfaces and on the port in the PORT environment variable, which Codara sets (8080 unless you choose another port). uvicorn needs --host 0.0.0.0 --port $PORT. gunicorn binds to 0.0.0.0:$PORT on its own when PORT is set.
3.12Which start command does Codara use?
Railpack recognises three common layouts and writes the start command itself. For anything else, add a railpack.json file at the root with your own start command; it takes precedence over the detected one.
{
"deploy": {
"startCommand": "uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-8080}"
}
}| Framework | Detected when | Start command |
|---|---|---|
| FastAPI | fastapi and uvicorn are dependencies and the app object is app in main.py at the root | uvicorn main:app --host 0.0.0.0 --port ${PORT:-8000} |
| Flask | gunicorn is a dependency and the app object is app in main.py at the root | gunicorn --bind 0.0.0.0:${PORT:-8000} main:app |
| Django | manage.py is at the root and django is a dependency; add gunicorn too | python manage.py migrate && gunicorn --bind 0.0.0.0:${PORT:-8000} <project>.wsgi:application |
| Anything else | Your own layout, e.g. app/main.py | The deploy.startCommand in railpack.json |
How do you create the app?
Install the Codara GitHub App on the repository’s owner and create a project. In the console, open Apps → New app, choose the project and environment, select GitHub repository and the branch, and submit. The wizard creates the app and starts its first build; every later push to the branch deploys again. Set a health check path, such as /health, in the app’s settings.
codaracloud apps create api --client my-workspace --project research \
--repo acme/research-api --branch main
codaracloud deploy api --client my-workspace --project research --source
codaracloud logs api --followHow do you connect Postgres and run migrations?
Create a Postgres database in the same environment and connect it to the app: Codara injects DATABASE_URL and DATABASE_DIRECT_URL and restarts the app. Read the connection URL from DATABASE_URL in your code; in Django, dj-database-url does it for you.
Run migrations as the app’s pre-deploy command, for example alembic upgrade head or python manage.py migrate. It runs once in the new image before traffic moves, and a failure keeps the current release serving. Railpack’s default Django command also runs migrate each time a container starts; if you prefer migrations only in the pre-deploy command, set your own start command in railpack.json.
import os
import dj_database_url
DATABASES = {"default": dj_database_url.config(conn_max_age=600)}
ALLOWED_HOSTS = os.environ.get("ALLOWED_HOSTS", "").split(",")
CSRF_TRUSTED_ORIGINS = [f"https://{h}" for h in ALLOWED_HOSTS if h]Set ALLOWED_HOSTS to your codara.cloud hostname and your own domain as a runtime variable, and SECRET_KEY as a secret. For static files, WhiteNoise is the usual choice with one container: run python manage.py collectstatic --noinput in your start command before gunicorn.
Where do Celery workers and scheduled tasks go?
A Celery or RQ worker is a separate service in the same environment, built from the same repository with its own start command. Codara also runs managed Redis for the broker. Scheduled work, such as a nightly report or a cleanup script, belongs in a Codara job with a cron expression rather than a sleeping loop in the web process.
Questions
- Do I need a Dockerfile for a Python app?
- No. Railpack builds Python apps from requirements.txt, pyproject.toml or a Pipfile. Add a Dockerfile only if you need system libraries or a base image of your own; Codara then uses it as written.
- Why does my app work locally but not on Codara?
- Usually the server listens on 127.0.0.1 or on a fixed port. Bind to 0.0.0.0 and to the PORT variable, and check the app’s logs after a release.
- Can I use uv or Poetry?
- Yes. With pyproject.toml, a uv.lock makes Railpack install with uv and a poetry.lock with Poetry.