litewave-logger 0.4.0

A lightweight logging library with context carry forward

Litewave Logger

This module provides a centralized and consistent logging solution for Litewave services. It ensures that a request-id is maintained across all services, including HTTP requests and Celery tasks, allowing for easy tracing of requests as they propagate through the system.

Features

• Centralized Logging: A single module to configure and manage logging across all services.
• JSON Logging: All logs are formatted as JSON for easy parsing and integration with log aggregation systems.
• Request ID Propagation: Automatically injects a request-id into all log messages.
• FastAPI Integration: Middleware for FastAPI to handle request-id for incoming HTTP requests and adds it to response headers.
• Celery Integration: Signal handlers to propagate the request-id to Celery tasks automatically.
• Requests Library Patching: Automatically injects the request-id into outgoing HTTP requests made with the requests library.
• Endpoint Exclusion: Configure endpoints that should not be logged (e.g., health checks, metrics).

Installation

1. Add the litewave_logger directory to your Python project.
2. Ensure that the dependencies listed in the main requirements.txt (fastapi, celery, requests) are installed.

Usage

To use the litewave_logger in your service, follow these steps:

1. Initialize the logger: In your main application file (e.g., api.py), import and call the setup_logging function. This should be done as early as possible.

   from litewave_logger import setup_logging
   
   # Optionally exclude endpoints from logging (e.g., health checks, metrics)
   setup_logging(excluded_endpoints=['/health', '/metrics'])
   

2. Add the FastAPI middleware: If your service is a FastAPI application, add the RequestIdMiddleware to your FastAPI app.

   from fastapi import FastAPI
   from litewave_logger.middleware import RequestIdMiddleware
   
   app = FastAPI()
   app.add_middleware(RequestIdMiddleware)
   

3. Patch the requests library: To ensure the request-id is propagated to other services, patch the requests library.

   from litewave_logger.requests import patch_requests
   
   patch_requests()
   

4. Connect Celery signals: If your service uses Celery, you need to import the Celery module to ensure the signal handlers are registered. The signal handlers are automatically connected via decorators, so you don't need to call them directly.

   # Just import the module - signal handlers are automatically registered
   import litewave_logger.celery
   

Example

Here's a complete example of how to integrate the litewave_logger into a FastAPI application:

from fastapi import FastAPI
from litewave_logger import setup_logging
from litewave_logger.middleware import RequestIdMiddleware
from litewave_logger.requests import patch_requests

# Import Celery module to register signal handlers (if using Celery)
import litewave_logger.celery

# 1. Initialize logging (optionally exclude endpoints)
setup_logging(excluded_endpoints=['/health', '/metrics'])

# 2. Patch requests library
patch_requests()

app = FastAPI()

# 3. Add RequestIdMiddleware
app.add_middleware(RequestIdMiddleware)

# Your application code here...

How It Works

Request ID Flow

1. Incoming HTTP Request: The RequestIdMiddleware checks for an X-Request-ID header. If present, it uses that value; otherwise, it generates a new UUID.
2. Context Variable: The request ID is stored in a context variable (request_id_var) that is automatically maintained across async operations.
3. Logging: All log messages automatically include the request ID via the RequestIdFilter.
4. Outgoing Requests: When using the requests library, the request ID is automatically injected as the X-Request-ID header.
5. Response Headers: The request ID is added to the response headers as X-Request-ID.
6. Celery Tasks: When a Celery task is published, the request ID is automatically included in the task headers and propagated to the worker process.

Log Format

All logs are formatted as JSON with the following structure:

{
  "timestamp": "2024-01-01 12:00:00",
  "level": "INFO",
  "request_id": "550e8400-e29b-41d4-a716-446655440000",
  "path": "/api/users",
  "method": "GET",
  "message": "request received",
  "status_code": 200,
  "error": null
}