Logging

aiohttp uses standard logging for tracking the library activity.

We have the following loggers enumerated by names:

  • 'aiohttp.access'
  • 'aiohttp.client'
  • 'aiohttp.internal'
  • 'aiohttp.server'
  • 'aiohttp.web'
  • 'aiohttp.websocket'

You may subscribe to these loggers for getting logging messages. The page does not provide instructions for logging subscribing while the most friendly method is logging.config.dictConfig() for configuring whole loggers in your application.

Access logs

Access log by default is switched on and uses 'aiohttp.access' logger name.

The log may be controlled by aiohttp.web.AppRunner() and aiohttp.web.run_app().

Pass access_log parameter with value of logging.Logger instance to override default logger.

Note

Use web.run_app(app, access_log=None) for disabling access logs.

Other parameter called access_log_format may be used for specifying log format (see below).

Format specification

The library provides custom micro-language to specifying info about request and response:

Option Meaning
%% The percent sign
%a Remote IP-address (IP-address of proxy if using reverse proxy)
%t Time when the request was started to process
%P The process ID of the child that serviced the request
%r First line of request
%s Response status code
%b Size of response in bytes, including HTTP headers
%T The time taken to serve the request, in seconds
%Tf The time taken to serve the request, in seconds with fraction in %.06f format
%D The time taken to serve the request, in microseconds
%{FOO}i request.headers['FOO']
%{FOO}o response.headers['FOO']

Default access log format is:

'%a %t "%r" %s %b "%{Referer}i" "%{User-Agent}i"'

New in version 2.3.0.

access_log_class introduced.

Example of drop-in replacement for aiohttp.helpers.AccessLogger:

from aiohttp.abc import AbstractAccessLogger

class AccessLogger(AbstractAccessLogger):

    def log(self, request, response, time):
        self.logger.info(f'{request.remote} '
                         f'"{request.method} {request.path} '
                         f'done in {time}s: {response.status}')

Gunicorn access logs

When Gunicorn is used for deployment its default access log format will be automatically replaced with the default aiohttp’s access log format.

If Gunicorn’s option access_logformat is specified explicitly it should use aiohttp’s format specification.

Gunicorn access log works only if accesslog is specified explicitly in your config or as a command line option. This configuration can be either a path or '-'. If the application uses a custom logging setup intercepting the 'gunicorn.access' logger, accesslog should be set to '-' to prevent Gunicorn to create an empty access log file upon every startup.

Error logs

aiohttp.web uses logger named 'aiohttp.server' to store errors given on web requests handling.

The log is enabled by default.

To use different logger name please pass logger parameter (logging.Logger instance) to aiohttp.web.AppRunner() constructor.