sanic/docs/sanic/logging.md

Logging

Sanic allows you to do different types of logging (access log, error log) on the requests based on the python3 logging API. You should have some basic knowledge on python3 logging if you want to create a new configuration.

Quick Start

A simple example using default settings would be like this:

from sanic import Sanic
from sanic.log import logger
from sanic.response import text

app = Sanic('test')

@app.route('/')
async def test(request):
    logger.info('Here is your log')
    return text('Hello World!')

if __name__ == "__main__":
  app.run(debug=True, access_log=True)

After the server is running, you can see some messages looks like:

[2018-11-06 21:16:53 +0800] [24622] [INFO] Goin' Fast @ http://127.0.0.1:8000
[2018-11-06 21:16:53 +0800] [24667] [INFO] Starting worker [24667]

You can send a request to server and it will print the log messages:

[2018-11-06 21:18:53 +0800] [25685] [INFO] Here is your log
[2018-11-06 21:18:53 +0800] - (sanic.access)[INFO][127.0.0.1:57038]: GET http://localhost:8000/  200 12

To use your own logging config, simply use logging.config.dictConfig, or pass log_config when you initialize Sanic app:

app = Sanic('test', log_config=LOGGING_CONFIG)

And to close logging, simply assign access_log=False:

if __name__ == "__main__":
  app.run(access_log=False)

This would skip calling logging functions when handling requests. And you could even do further in production to gain extra speed:

if __name__ == "__main__":
  # disable debug messages
  app.run(debug=False, access_log=False)

Configuration

By default, log_config parameter is set to use sanic.log.LOGGING_CONFIG_DEFAULTS dictionary for configuration.

There are three loggers used in sanic, and must be defined if you want to create your own logging configuration:

• sanic.root:
  Used to log internal messages.

• sanic.error:
  Used to log error logs.

• sanic.access:
  Used to log access logs.

Log format:

In addition to default parameters provided by python (asctime, levelname, message), Sanic provides additional parameters for access logger with:

• host (str)
  request.ip

• request (str)
  request.method + " " + request.url

• status (int)
  response.status

• byte (int)
  len(response.body)

The default access log format is

%(asctime)s - (%(name)s)[%(levelname)s][%(host)s]: %(request)s %(message)s %(status)d %(byte)d