https://github.com/dantetemplar/fastapi-how-to-log
Way to improve logging for FastAPI projects.
https://github.com/dantetemplar/fastapi-how-to-log
fastapi logging python
Last synced: 8 months ago
JSON representation
Way to improve logging for FastAPI projects.
- Host: GitHub
- URL: https://github.com/dantetemplar/fastapi-how-to-log
- Owner: dantetemplar
- License: mit
- Created: 2025-07-27T18:13:45.000Z (11 months ago)
- Default Branch: main
- Last Pushed: 2025-07-27T19:00:12.000Z (11 months ago)
- Last Synced: 2025-07-27T20:54:12.819Z (11 months ago)
- Topics: fastapi, logging, python
- Language: Python
- Homepage:
- Size: 38.1 KB
- Stars: 7
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# FastAPI Enhanced Logging
A comprehensive logging solution for FastAPI applications that provides enhanced debugging capabilities, performance monitoring, and cleaner log output.
## Features
### 🔗 Clickable Source Code Links
- **IDE Integration**: Log messages include clickable file paths that work in both PyCharm and VS Code
- **Precise Location**: Shows exact line numbers where log messages originate
- **Relative Paths**: Uses relative paths for cleaner output
https://github.com/user-attachments/assets/1badb8a6-b525-405e-8e5f-e5585be2be37
### 🧹 Clean Log Output
- **Reduced Boilerplate**: Filters out verbose FastAPI and uvicorn logs
- **HTTPX Filtering**: Suppresses noisy HTTP client library logs
- **Error Focus**: Shows only your application's errors, not framework noise
- **Stack Trace Cleanup**: Removes irrelevant framework stack
https://github.com/user-attachments/assets/572d0217-c10d-4af8-b4d8-deeac88ceb54
### ⏱️ Performance Monitoring
- **Handler Timing**: Automatically measures and logs execution time for each endpoint handler
🚨 Exception Handling & Logging
- **Validation Error Logging**: Automatically logs Pydantic validation errors with detailed context
- **HTTP Exception Tracking**: Captures and logs HTTP exceptions with proper error details
- **Human Readable Error Messages**: Returns clean error messages while maintaining comprehensive logging
## Usage
Copy the `logging_.py` module into your project and use it as follows:
```python
import logging_ # noqa
from logging_ import logger
from fastapi import FastAPI, HTTPException
from fastapi.exception_handlers import http_exception_handler
from fastapi.exceptions import RequestValidationError
from fastapi.requests import Request
from fastapi.responses import PlainTextResponse
from pydantic import ValidationError
from starlette.exceptions import HTTPException as StarletteHTTPException
app = FastAPI()
@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
as_validation_error = ValidationError.from_exception_data(
str(request.url.path),
line_errors=exc.errors(),
)
error_str = str(as_validation_error)
logger.warning(error_str, exc_info=False)
return PlainTextResponse(error_str, status_code=422)
@app.exception_handler(StarletteHTTPException)
async def custom_http_exception_handler(request: Request, exc: StarletteHTTPException):
logger.warning(exc, exc_info=exc)
return await http_exception_handler(request, exc)
@app.get("/")
async def root():
logger.info("This will show with source code location and timing")
return {"message": "Hello World"}
@app.get("/error")
async def error():
raise Exception("This is a test error")
```
## Example Output
```
[2025-07-27 20:24:48,880] [INFO] [File "app.py", line 19] This will show with source code location and timing
[2025-07-27 20:24:48,880] [INFO] [File "app.py", line 20] Handler `root` took 1 ms
[2025-07-27 21:59:30,463] [INFO] [uvicorn.access] 127.0.0.1:59962 - "GET /error HTTP/1.1" 500
[2025-07-27 21:59:30,464] [ERROR] [uvicorn.error] Exception in ASGI application
Traceback (most recent call last):
File "/home/dante/fastapi-how-to-log/app.py", line 54, in error
raise Exception("This is a test error")
Exception: This is a test error
```
The file path in the log message will be clickable ([File "app.py", line 19]) in your IDE, taking you directly to the source code.
## Customization
You can modify the `dictConfig` in `logging_.py` to adjust:
- Log levels for different components
- Output formatting
- Color schemes
- Filtered paths and libraries
## How It Works
### Source Code Linking
The `RelativePathFilter` adds relative file paths to log records, making them clickable in IDEs.
### Performance Monitoring
The `run_endpoint_function` is monkey-patched into FastAPI to automatically measure handler execution time.
### Log Filtering
The `CleanErrorFilter` removes framework noise from stack traces and suppresses unwanted log sources.
### Exception Handling
The custom exception handlers provide structured logging for validation errors and HTTP exceptions:
- **Validation Errors**: Converts FastAPI's `RequestValidationError` to Pydantic's `ValidationError` format for human readable messages
- **HTTP Exceptions**: Logs HTTP exceptions with full context while maintaining FastAPI's default error response behavior
## ⚠️ Disclaimer
**This solution uses some "cursed" techniques:**
- **Monkey Patching**: Directly modifies FastAPI's internal `run_endpoint_function`
- **Internal API Usage**: Relies on FastAPI's internal dependency injection system
- **Framework Coupling**: Tightly coupled to specific FastAPI and Starlette versions
While effective, these techniques may break with framework updates. Use at your own risk in production environments.
## Requirements
- Python 3.11+
- FastAPI
- colorlog
- uvicorn (for ASGI server)
## License
MIT License - feel free to use and modify as needed.