How to Log Requests in FastAPI: Simple Guide with Examples

To log requests in FastAPI, create a custom middleware that intercepts each request and logs details like method and URL. Use BaseHTTPMiddleware from starlette.middleware.base to add this middleware to your app.

Syntax

Use BaseHTTPMiddleware to create a middleware class that intercepts requests. Override the dispatch method to access the request object and log its properties before passing control to the next handler.

Then add this middleware to your FastAPI app with add_middleware().

python

from fastapi import FastAPI, Request
from starlette.middleware.base import BaseHTTPMiddleware
import logging

class LogRequestsMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        logging.info(f"Request: {request.method} {request.url}")
        response = await call_next(request)
        return response

app = FastAPI()
app.add_middleware(LogRequestsMiddleware)

Example

This example shows a FastAPI app with a middleware that logs each incoming request's method and URL to the console.

python

import logging
from fastapi import FastAPI, Request
from starlette.middleware.base import BaseHTTPMiddleware

logging.basicConfig(level=logging.INFO)

class LogRequestsMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        logging.info(f"Request: {request.method} {request.url}")
        response = await call_next(request)
        return response

app = FastAPI()
app.add_middleware(LogRequestsMiddleware)

@app.get("/")
async def read_root():
    return {"message": "Hello World"}

Output

INFO:root:Request: GET http://127.0.0.1:8000/

Common Pitfalls

• Not awaiting call_next(request) causes the request to hang.
• Logging too much data synchronously can slow down requests.
• For production, configure logging properly instead of using print.
• Middleware order matters; place logging middleware early to capture all requests.

python

from fastapi import FastAPI, Request
from starlette.middleware.base import BaseHTTPMiddleware
import logging

# Wrong: forgetting to await call_next
class BadMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        logging.info(f"Request: {request.method} {request.url}")
        response = call_next(request)  # Missing await
        return response

# Correct:
class GoodMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        logging.info(f"Request: {request.method} {request.url}")
        response = await call_next(request)
        return response

Quick Reference

• Use BaseHTTPMiddleware to create request logging middleware.
• Override dispatch to log request details.
• Always await call_next(request) to continue processing.
• Configure Python's logging module for better control.

Key Takeaways

Create a custom middleware by subclassing BaseHTTPMiddleware to log requests in FastAPI.

Always await call_next(request) inside dispatch to avoid blocking requests.

Use Python's logging module instead of print for better log management.

Place logging middleware early to capture all incoming requests.

Keep logging lightweight to avoid slowing down your API responses.