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.. _aiohttp-logging: |
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Logging |
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======= |
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.. currentmodule:: aiohttp |
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*aiohttp* uses standard :mod:`logging` for tracking the |
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library activity. |
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We have the following loggers enumerated by names: |
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- ``'aiohttp.access'`` |
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- ``'aiohttp.client'`` |
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- ``'aiohttp.internal'`` |
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- ``'aiohttp.server'`` |
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- ``'aiohttp.web'`` |
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- ``'aiohttp.websocket'`` |
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You may subscribe to these loggers for getting logging messages. The |
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page does not provide instructions for logging subscribing while the |
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most friendly method is :func:`logging.config.dictConfig` for |
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configuring whole loggers in your application. |
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Logging does not work out of the box. It requires at least minimal ``'logging'`` |
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configuration. |
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Example of minimal working logger setup:: |
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import logging |
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from aiohttp import web |
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app = web.Application() |
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logging.basicConfig(level=logging.DEBUG) |
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web.run_app(app, port=5000) |
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.. versionadded:: 4.0.0 |
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Access logs |
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----------- |
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Access logs are enabled by default. If the `debug` flag is set, and the default |
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logger ``'aiohttp.access'`` is used, access logs will be output to |
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:obj:`~sys.stderr` if no handlers are attached. |
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Furthermore, if the default logger has no log level set, the log level will be |
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set to :obj:`logging.DEBUG`. |
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This logging may be controlled by :meth:`aiohttp.web.AppRunner` and |
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:func:`aiohttp.web.run_app`. |
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To override the default logger, pass an instance of :class:`logging.Logger` to |
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override the default logger. |
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.. note:: |
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Use ``web.run_app(app, access_log=None)`` to disable access logs. |
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In addition, *access_log_format* may be used to specify the log format. |
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.. _aiohttp-logging-access-log-format-spec: |
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Format specification |
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^^^^^^^^^^^^^^^^^^^^ |
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The library provides custom micro-language to specifying info about |
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request and response: |
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+--------------+---------------------------------------------------------+ |
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| Option | Meaning | |
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+==============+=========================================================+ |
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| ``%%`` | The percent sign | |
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+--------------+---------------------------------------------------------+ |
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| ``%a`` | Remote IP-address | |
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| | (IP-address of proxy if using reverse proxy) | |
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+--------------+---------------------------------------------------------+ |
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| ``%t`` | Time when the request was started to process | |
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+--------------+---------------------------------------------------------+ |
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| ``%P`` | The process ID of the child that serviced the request | |
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+--------------+---------------------------------------------------------+ |
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| ``%r`` | First line of request | |
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+--------------+---------------------------------------------------------+ |
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| ``%s`` | Response status code | |
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+--------------+---------------------------------------------------------+ |
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| ``%b`` | Size of response in bytes, including HTTP headers | |
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+--------------+---------------------------------------------------------+ |
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| ``%T`` | The time taken to serve the request, in seconds | |
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+--------------+---------------------------------------------------------+ |
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| ``%Tf`` | The time taken to serve the request, in seconds | |
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| | with fraction in %.06f format | |
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+--------------+---------------------------------------------------------+ |
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| ``%D`` | The time taken to serve the request, in microseconds | |
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+--------------+---------------------------------------------------------+ |
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| ``%{FOO}i`` | ``request.headers['FOO']`` | |
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+--------------+---------------------------------------------------------+ |
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| ``%{FOO}o`` | ``response.headers['FOO']`` | |
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+--------------+---------------------------------------------------------+ |
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The default access log format is:: |
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'%a %t "%r" %s %b "%{Referer}i" "%{User-Agent}i"' |
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.. versionadded:: 2.3.0 |
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*access_log_class* introduced. |
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Example of a drop-in replacement for the default access logger:: |
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from aiohttp.abc import AbstractAccessLogger |
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class AccessLogger(AbstractAccessLogger): |
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def log(self, request, response, time): |
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self.logger.info(f'{request.remote} ' |
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f'"{request.method} {request.path} ' |
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f'done in {time}s: {response.status}') |
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.. _gunicorn-accesslog: |
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Gunicorn access logs |
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^^^^^^^^^^^^^^^^^^^^ |
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When `Gunicorn <http://docs.gunicorn.org/en/latest/index.html>`_ is used for |
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:ref:`deployment <aiohttp-deployment-gunicorn>`, its default access log format |
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will be automatically replaced with the default aiohttp's access log format. |
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If Gunicorn's option access_logformat_ is |
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specified explicitly, it should use aiohttp's format specification. |
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Gunicorn's access log works only if accesslog_ is specified explicitly in your |
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config or as a command line option. |
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This configuration can be either a path or ``'-'``. If the application uses |
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a custom logging setup intercepting the ``'gunicorn.access'`` logger, |
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accesslog_ should be set to ``'-'`` to prevent Gunicorn to create an empty |
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access log file upon every startup. |
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Error logs |
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---------- |
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:mod:`aiohttp.web` uses a logger named ``'aiohttp.server'`` to store errors |
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given on web requests handling. |
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This log is enabled by default. |
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To use a different logger name, pass *logger* (:class:`logging.Logger` |
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instance) to the :meth:`aiohttp.web.AppRunner` constructor. |
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.. _access_logformat: |
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http://docs.gunicorn.org/en/stable/settings.html#access-log-format |
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.. _accesslog: |
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http://docs.gunicorn.org/en/stable/settings.html#accesslog |
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