.. currentmodule:: aiohttp .. _aiohttp-logging: Logging ======= *aiohttp* uses standard :mod:`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 :func:`logging.config.dictConfig` for configuring whole loggers in your application. Logging does not work out of the box. It requires at least minimal ``'logging'`` configuration. Example of minimal working logger setup:: import logging from aiohttp import web app = web.Application() logging.basicConfig(level=logging.DEBUG) web.run_app(app, port=5000) .. versionadded:: 4.0.0 Access logs ----------- Access logs are enabled by default. If the `debug` flag is set, and the default logger ``'aiohttp.access'`` is used, access logs will be output to :obj:`~sys.stderr` if no handlers are attached. Furthermore, if the default logger has no log level set, the log level will be set to :obj:`logging.DEBUG`. This logging may be controlled by :meth:`aiohttp.web.AppRunner` and :func:`aiohttp.web.run_app`. To override the default logger, pass an instance of :class:`logging.Logger` to override the default logger. .. note:: Use ``web.run_app(app, access_log=None)`` to disable access logs. In addition, *access_log_format* may be used to specify the log format. .. _aiohttp-logging-access-log-format-spec: 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']`` | +--------------+---------------------------------------------------------+ The default access log format is:: '%a %t "%r" %s %b "%{Referer}i" "%{User-Agent}i"' .. versionadded:: 2.3.0 *access_log_class* introduced. Example of a drop-in replacement for the default access logger:: 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}') .. versionadded:: 4.0.0 ``AccessLogger.log()`` can now access any exception raised while processing the request with ``sys.exc_info()``. .. versionadded:: 4.0.0 If your logging needs to perform IO you can instead inherit from :class:`aiohttp.abc.AbstractAsyncAccessLogger`:: from aiohttp.abc import AbstractAsyncAccessLogger class AccessLogger(AbstractAsyncAccessLogger): async def log(self, request, response, time): logging_service = request.app['logging_service'] await logging_service.log(f'{request.remote} ' f'"{request.method} {request.path} ' f'done in {time}s: {response.status}') This also allows access to the results of coroutines on the ``request`` and ``response``, e.g. ``request.text()``. .. _gunicorn-accesslog: Gunicorn access logs ^^^^^^^^^^^^^^^^^^^^ When `Gunicorn `_ is used for :ref:`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's 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 ---------- :mod:`aiohttp.web` uses a logger named ``'aiohttp.server'`` to store errors given on web requests handling. This log is enabled by default. To use a different logger name, pass *logger* (:class:`logging.Logger` instance) to the :meth:`aiohttp.web.AppRunner` constructor. .. _access_logformat: http://docs.gunicorn.org/en/stable/settings.html#access-log-format .. _accesslog: http://docs.gunicorn.org/en/stable/settings.html#accesslog