How to add timestamp to each request in uvicorn logs?

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06-10-2024

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Logging Timestamps in Your Uvicorn Requests: A Simple Guide

Uvicorn, a lightning-fast ASGI server, is a popular choice for Python web development. While it provides excellent performance, getting detailed logging information can sometimes be a challenge. One crucial detail often missing is the timestamp for each request.

This article will guide you through the process of adding timestamps to your Uvicorn logs, ensuring you have a clear picture of when requests are coming in and how long they take to process.

Scenario: Imagine you're working on a web application and need to investigate potential performance bottlenecks. You're running your application with Uvicorn, but the default logs lack timestamps, making it difficult to track request timings.

Original Code (Default Uvicorn logging):

import uvicorn

from fastapi import FastAPI

app = FastAPI()

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

if __name__ == "__main__":
    uvicorn.run(app, host="127.0.0.1", port=8000)

Adding Timestamps:

The easiest way to add timestamps is using the access_log parameter in uvicorn.run. This allows you to customize the logging format to include timestamps alongside other request details.

Enhanced Code with Timestamps:

import uvicorn

from fastapi import FastAPI

app = FastAPI()

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

if __name__ == "__main__":
    uvicorn.run(app, host="127.0.0.1", port=8000,
                access_log=True,
                log_config={"format": "%(asctime)s - %(levelname)s - %(message)s"})

Explanation:

1. We set access_log=True to enable access logging.
2. We provide a log_config dictionary to customize the logging format.
3. The format key defines the structure of each log message, with %(asctime)s specifically inserting the timestamp.

Additional Insights:

• The default log_config for Uvicorn doesn't include a timestamp. You can refer to the Uvicorn documentation for more information about logging configurations.
• The logging module in Python provides advanced control over your logging. You can customize log levels, create custom log handlers, and even rotate log files based on size or time.
• If you're looking for detailed insights into your application's performance, consider using profiling tools like cProfile or tracing libraries like OpenTelemetry. These tools can provide granular information about function calls, execution times, and resource usage.

Conclusion:

Adding timestamps to your Uvicorn logs is a simple yet essential step for effective debugging and performance analysis. By customizing the logging format, you gain valuable insights into your application's behavior and identify potential issues quickly. Remember to leverage the power of Python's logging module and explore profiling tools for a comprehensive understanding of your web application's performance.