How do you deploy FastAPI in production?

Summary

Run Uvicorn with multiple worker processes (uvicorn --workers N or Gunicorn with uvicorn.workers.UvicornWorker), behind a reverse proxy or load balancer, usually in containers, with health checks and proper proxy header handling.

Longer Answer

Rule of thumb: start with workers ≈ CPU cores and tune with load tests. In Kubernetes, many teams run one worker per container and scale pods instead. Set --proxy-headers and --forwarded-allow-ips behind a proxy so request.client and scheme are right. The FastAPI CLI (fastapi run) wraps Uvicorn for production.

Code Example

# Dockerfile (simplified)
FROM python:3.13-slim
WORKDIR /app
COPY pyproject.toml uv.lock ./
RUN pip install uv && uv sync --frozen --no-dev
COPY app ./app
CMD ["uv", "run", "uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000", "--workers", "4", "--proxy-headers"]

Key Points

• Multiple worker processes for CPU parallelism
• Reverse proxy/LB in front (TLS, buffering)
• One worker per container in Kubernetes is common
• Health/readiness endpoints