Category: devops

Skip the tutorials that break in production. Here's how to set up FastAPI properly from day one.

Most FastAPI tutorials get you running in 5 minutes. Then you spend 5 hours figuring out why it breaks in production.

We've deployed dozens of FastAPI servers. Here's what actually works.

The setup that doesn't lie to you

First, forget uvicorn main:app --reload for anything beyond your laptop. Here's the production-ready structure:

your-api/
├── app/
│   ├── __init__.py
│   ├── main.py
│   ├── models/
│   ├── routers/
│   └── dependencies.py
├── requirements.txt
├── docker-compose.yml
└── gunicorn.conf.py

gunicorn.conf.py is the real MVP

This file is where tutorials fail you:

bind = "0.0.0.0:8000"
workers = 4
worker_class = "uvicorn.workers.UvicornWorker"
max_requests = 1000
max_requests_jitter = 50
preload_app = True
timeout = 30
keepalive = 2

Why these settings matter:

max_requests prevents memory leaks from killing your server
preload_app saves memory when you scale workers
timeout = 30 because your database queries will sometimes be slow

Environment variables that don't suck

Use Pydantic's BaseSettings. It's not optional:

from pydantic_settings import BaseSettings

class Settings(BaseSettings):
    database_url: str
    secret_key: str
    debug: bool = False

    class Config:
        env_file = ".env"

Docker that works

Multi-stage builds aren't just for show-offs:

FROM python:3.11-slim as builder
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir --user -r requirements.txt

FROM python:3.11-slim
WORKDIR /app
COPY --from=builder /root/.local /root/.local
COPY . .
CMD ["gunicorn", "app.main:app"]

The part nobody talks about

Health checks. Your container orchestrator needs to know if your app is actually working:

@app.get("/health")
def health_check():
    return {"status": "healthy", "timestamp": datetime.utcnow()}

Add this to your Docker Compose:

healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
  interval: 30s
  timeout: 10s
  retries: 3

What we learned the hard way

After deploying FastAPI in production for 3 years:

CORS will bite you. Configure it early, not when your frontend team starts swearing.
Database connections leak. Use connection pooling from day one.
Logs matter. Structure them. Your future debugging self will thank you.
Version your API. /v1/ in the URL saves relationships later.