fastapi

FastAPI Example

This example demonstrates building a FastAPI web service using the Python Container Builder.

Features Demonstrated

• ✅ Web service with external dependencies
• ✅ Using uv for fast dependency installation
• ✅ Multi-stage build to distroless runtime
• ✅ Health check endpoint

Project Structure

fastapi/
├── Dockerfile
├── requirements.txt
└── main.py

Building the Image

docker build -t fastapi-example .

Running the Container

docker run -p 8000:8000 fastapi-example

Then visit http://localhost:8000/docs to see the interactive API documentation.

Testing the API

# Health check
curl http://localhost:8000/health

# Get current time
curl http://localhost:8000/time

# Echo endpoint
curl -X POST http://localhost:8000/echo \
  -H "Content-Type: application/json" \
  -d '{"message": "Hello, World!"}'

Key Dockerfile Patterns

Build Stage

FROM ghcr.io/jski/python-container-builder:3.12 as build-venv
COPY requirements.txt /requirements.txt
RUN uv pip install -r /requirements.txt

Runtime Stage

FROM gcr.io/distroless/python3-debian12
COPY --from=build-venv /.venv /.venv
COPY main.py /app/main.py
WORKDIR /app
ENTRYPOINT ["/.venv/bin/python3", "-u", "main.py"]

Why This Works

1. Fast builds - uv installs dependencies much faster than pip
2. Small images - Distroless runtime contains only what's needed
3. Security - No package manager or shell in final image
4. Reliable - Virtual environment ensures dependency isolation

Customization

Different Python Version

Change the build image tag:

FROM ghcr.io/jski/python-container-builder:3.11 as build-venv
# Also change the runtime to match:
FROM gcr.io/distroless/python3-debian12

Add More Dependencies

Just update requirements.txt and rebuild. The build cache will reuse unchanged layers.

Production Settings

Consider adding:

• Environment variable for host/port configuration
• Multiple workers (uvicorn --workers)
• Health check monitoring
• Logging configuration