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<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.config</span></code> — Logging configuration</a><ul>
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<li><a class="reference internal" href="#configuration-functions">Configuration functions</a></li>
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<section id="module-logging.config">
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<span id="logging-config-logging-configuration"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.config</span></code> — Logging configuration<a class="headerlink" href="#module-logging.config" title="Link to this heading">¶</a></h1>
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<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/logging/config.py">Lib/logging/config.py</a></p>
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<li><p><a class="reference internal" href="../howto/logging.html#logging-basic-tutorial"><span class="std std-ref">Basic Tutorial</span></a></p></li>
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<li><p><a class="reference internal" href="../howto/logging.html#logging-advanced-tutorial"><span class="std std-ref">Advanced Tutorial</span></a></p></li>
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<li><p><a class="reference internal" href="../howto/logging-cookbook.html#logging-cookbook"><span class="std std-ref">Logging Cookbook</span></a></p></li>
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<p>This section describes the API for configuring the logging module.</p>
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<section id="configuration-functions">
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<span id="logging-config-api"></span><h2>Configuration functions<a class="headerlink" href="#configuration-functions" title="Link to this heading">¶</a></h2>
|
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<p>The following functions configure the logging module. They are located in the
|
||
<a class="reference internal" href="#module-logging.config" title="logging.config: Configuration of the logging module."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.config</span></code></a> module. Their use is optional — you can configure the
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logging module using these functions or by making calls to the main API (defined
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in <a class="reference internal" href="logging.html#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code></a> itself) and defining handlers which are declared either in
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<a class="reference internal" href="logging.html#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code></a> or <a class="reference internal" href="logging.handlers.html#module-logging.handlers" title="logging.handlers: Handlers for the logging module."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.handlers</span></code></a>.</p>
|
||
<dl class="py function">
|
||
<dt class="sig sig-object py" id="logging.config.dictConfig">
|
||
<span class="sig-prename descclassname"><span class="pre">logging.config.</span></span><span class="sig-name descname"><span class="pre">dictConfig</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">config</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#logging.config.dictConfig" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Takes the logging configuration from a dictionary. The contents of
|
||
this dictionary are described in <a class="reference internal" href="#logging-config-dictschema"><span class="std std-ref">Configuration dictionary schema</span></a>
|
||
below.</p>
|
||
<p>If an error is encountered during configuration, this function will
|
||
raise a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>, <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>, <a class="reference internal" href="exceptions.html#AttributeError" title="AttributeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">AttributeError</span></code></a>
|
||
or <a class="reference internal" href="exceptions.html#ImportError" title="ImportError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ImportError</span></code></a> with a suitably descriptive message. The
|
||
following is a (possibly incomplete) list of conditions which will
|
||
raise an error:</p>
|
||
<ul class="simple">
|
||
<li><p>A <code class="docutils literal notranslate"><span class="pre">level</span></code> which is not a string or which is a string not
|
||
corresponding to an actual logging level.</p></li>
|
||
<li><p>A <code class="docutils literal notranslate"><span class="pre">propagate</span></code> value which is not a boolean.</p></li>
|
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<li><p>An id which does not have a corresponding destination.</p></li>
|
||
<li><p>A non-existent handler id found during an incremental call.</p></li>
|
||
<li><p>An invalid logger name.</p></li>
|
||
<li><p>Inability to resolve to an internal or external object.</p></li>
|
||
</ul>
|
||
<p>Parsing is performed by the <code class="xref py py-class docutils literal notranslate"><span class="pre">DictConfigurator</span></code> class, whose
|
||
constructor is passed the dictionary used for configuration, and
|
||
has a <code class="xref py py-meth docutils literal notranslate"><span class="pre">configure()</span></code> method. The <a class="reference internal" href="#module-logging.config" title="logging.config: Configuration of the logging module."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.config</span></code></a> module
|
||
has a callable attribute <code class="xref py py-attr docutils literal notranslate"><span class="pre">dictConfigClass</span></code>
|
||
which is initially set to <code class="xref py py-class docutils literal notranslate"><span class="pre">DictConfigurator</span></code>.
|
||
You can replace the value of <code class="xref py py-attr docutils literal notranslate"><span class="pre">dictConfigClass</span></code> with a
|
||
suitable implementation of your own.</p>
|
||
<p><a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a> calls <code class="xref py py-attr docutils literal notranslate"><span class="pre">dictConfigClass</span></code> passing
|
||
the specified dictionary, and then calls the <code class="xref py py-meth docutils literal notranslate"><span class="pre">configure()</span></code> method on
|
||
the returned object to put the configuration into effect:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">def</span><span class="w"> </span><span class="nf">dictConfig</span><span class="p">(</span><span class="n">config</span><span class="p">):</span>
|
||
<span class="n">dictConfigClass</span><span class="p">(</span><span class="n">config</span><span class="p">)</span><span class="o">.</span><span class="n">configure</span><span class="p">()</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>For example, a subclass of <code class="xref py py-class docutils literal notranslate"><span class="pre">DictConfigurator</span></code> could call
|
||
<code class="docutils literal notranslate"><span class="pre">DictConfigurator.__init__()</span></code> in its own <code class="xref py py-meth docutils literal notranslate"><span class="pre">__init__()</span></code>, then
|
||
set up custom prefixes which would be usable in the subsequent
|
||
<code class="xref py py-meth docutils literal notranslate"><span class="pre">configure()</span></code> call. <code class="xref py py-attr docutils literal notranslate"><span class="pre">dictConfigClass</span></code> would be bound to
|
||
this new subclass, and then <a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a> could be called exactly as
|
||
in the default, uncustomized state.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.2.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py function">
|
||
<dt class="sig sig-object py" id="logging.config.fileConfig">
|
||
<span class="sig-prename descclassname"><span class="pre">logging.config.</span></span><span class="sig-name descname"><span class="pre">fileConfig</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fname</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">defaults</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">disable_existing_loggers</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">encoding</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#logging.config.fileConfig" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Reads the logging configuration from a <a class="reference internal" href="configparser.html#module-configparser" title="configparser: Configuration file parser."><code class="xref py py-mod docutils literal notranslate"><span class="pre">configparser</span></code></a>-format file. The
|
||
format of the file should be as described in
|
||
<a class="reference internal" href="#logging-config-fileformat"><span class="std std-ref">Configuration file format</span></a>.
|
||
This function can be called several times from an application, allowing an
|
||
end user to select from various pre-canned configurations (if the developer
|
||
provides a mechanism to present the choices and load the chosen
|
||
configuration).</p>
|
||
<p>It will raise <a class="reference internal" href="exceptions.html#FileNotFoundError" title="FileNotFoundError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">FileNotFoundError</span></code></a> if the file
|
||
doesn’t exist and <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a> if the file is invalid or
|
||
empty.</p>
|
||
<dl class="field-list simple">
|
||
<dt class="field-odd">Parameters<span class="colon">:</span></dt>
|
||
<dd class="field-odd"><ul class="simple">
|
||
<li><p><strong>fname</strong> – A filename, or a file-like object, or an instance derived
|
||
from <a class="reference internal" href="configparser.html#configparser.RawConfigParser" title="configparser.RawConfigParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">RawConfigParser</span></code></a>. If a
|
||
<code class="xref py py-class docutils literal notranslate"><span class="pre">RawConfigParser</span></code>-derived instance is passed, it is used as
|
||
is. Otherwise, a <a class="reference internal" href="configparser.html#configparser.ConfigParser" title="configparser.ConfigParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">ConfigParser</span></code></a> is
|
||
instantiated, and the configuration read by it from the
|
||
object passed in <code class="docutils literal notranslate"><span class="pre">fname</span></code>. If that has a <a class="reference internal" href="readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-meth docutils literal notranslate"><span class="pre">readline()</span></code></a>
|
||
method, it is assumed to be a file-like object and read using
|
||
<a class="reference internal" href="configparser.html#configparser.ConfigParser.read_file" title="configparser.ConfigParser.read_file"><code class="xref py py-meth docutils literal notranslate"><span class="pre">read_file()</span></code></a>; otherwise,
|
||
it is assumed to be a filename and passed to
|
||
<a class="reference internal" href="configparser.html#configparser.ConfigParser.read" title="configparser.ConfigParser.read"><code class="xref py py-meth docutils literal notranslate"><span class="pre">read()</span></code></a>.</p></li>
|
||
<li><p><strong>defaults</strong> – Defaults to be passed to the <code class="xref py py-class docutils literal notranslate"><span class="pre">ConfigParser</span></code> can be specified
|
||
in this argument.</p></li>
|
||
<li><p><strong>disable_existing_loggers</strong> – If specified as <code class="docutils literal notranslate"><span class="pre">False</span></code>, loggers which
|
||
exist when this call is made are left
|
||
enabled. The default is <code class="docutils literal notranslate"><span class="pre">True</span></code> because this
|
||
enables old behaviour in a
|
||
backward-compatible way. This behaviour is to
|
||
disable any existing non-root loggers unless
|
||
they or their ancestors are explicitly named
|
||
in the logging configuration.</p></li>
|
||
<li><p><strong>encoding</strong> – The encoding used to open file when <em>fname</em> is filename.</p></li>
|
||
</ul>
|
||
</dd>
|
||
</dl>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.4: </span>An instance of a subclass of <a class="reference internal" href="configparser.html#configparser.RawConfigParser" title="configparser.RawConfigParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">RawConfigParser</span></code></a> is
|
||
now accepted as a value for <code class="docutils literal notranslate"><span class="pre">fname</span></code>. This facilitates:</p>
|
||
<blockquote>
|
||
<div><ul class="simple">
|
||
<li><p>Use of a configuration file where logging configuration is just part
|
||
of the overall application configuration.</p></li>
|
||
<li><p>Use of a configuration read from a file, and then modified by the using
|
||
application (e.g. based on command-line parameters or other aspects
|
||
of the runtime environment) before being passed to <code class="docutils literal notranslate"><span class="pre">fileConfig</span></code>.</p></li>
|
||
</ul>
|
||
</div></blockquote>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.10: </span>Added the <em>encoding</em> parameter.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.12: </span>An exception will be thrown if the provided file
|
||
doesn’t exist or is invalid or empty.</p>
|
||
</div>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py function">
|
||
<dt class="sig sig-object py" id="logging.config.listen">
|
||
<span class="sig-prename descclassname"><span class="pre">logging.config.</span></span><span class="sig-name descname"><span class="pre">listen</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">port</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">DEFAULT_LOGGING_CONFIG_PORT</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">verify</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#logging.config.listen" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Starts up a socket server on the specified port, and listens for new
|
||
configurations. If no port is specified, the module’s default
|
||
<code class="xref py py-const docutils literal notranslate"><span class="pre">DEFAULT_LOGGING_CONFIG_PORT</span></code> is used. Logging configurations will be
|
||
sent as a file suitable for processing by <a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a> or
|
||
<a class="reference internal" href="#logging.config.fileConfig" title="logging.config.fileConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">fileConfig()</span></code></a>. Returns a <a class="reference internal" href="threading.html#threading.Thread" title="threading.Thread"><code class="xref py py-class docutils literal notranslate"><span class="pre">Thread</span></code></a> instance on which
|
||
you can call <a class="reference internal" href="threading.html#threading.Thread.start" title="threading.Thread.start"><code class="xref py py-meth docutils literal notranslate"><span class="pre">start()</span></code></a> to start the server, and which
|
||
you can <a class="reference internal" href="threading.html#threading.Thread.join" title="threading.Thread.join"><code class="xref py py-meth docutils literal notranslate"><span class="pre">join()</span></code></a> when appropriate. To stop the server,
|
||
call <a class="reference internal" href="#logging.config.stopListening" title="logging.config.stopListening"><code class="xref py py-func docutils literal notranslate"><span class="pre">stopListening()</span></code></a>.</p>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">verify</span></code> argument, if specified, should be a callable which should
|
||
verify whether bytes received across the socket are valid and should be
|
||
processed. This could be done by encrypting and/or signing what is sent
|
||
across the socket, such that the <code class="docutils literal notranslate"><span class="pre">verify</span></code> callable can perform
|
||
signature verification and/or decryption. The <code class="docutils literal notranslate"><span class="pre">verify</span></code> callable is called
|
||
with a single argument - the bytes received across the socket - and should
|
||
return the bytes to be processed, or <code class="docutils literal notranslate"><span class="pre">None</span></code> to indicate that the bytes should
|
||
be discarded. The returned bytes could be the same as the passed in bytes
|
||
(e.g. when only verification is done), or they could be completely different
|
||
(perhaps if decryption were performed).</p>
|
||
<p>To send a configuration to the socket, read in the configuration file and
|
||
send it to the socket as a sequence of bytes preceded by a four-byte length
|
||
string packed in binary using <code class="docutils literal notranslate"><span class="pre">struct.pack('>L',</span> <span class="pre">n)</span></code>.</p>
|
||
<div class="admonition note" id="logging-eval-security">
|
||
<p class="admonition-title">Note</p>
|
||
<p>Because portions of the configuration are passed through
|
||
<a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>, use of this function may open its users to a security risk.
|
||
While the function only binds to a socket on <code class="docutils literal notranslate"><span class="pre">localhost</span></code>, and so does
|
||
not accept connections from remote machines, there are scenarios where
|
||
untrusted code could be run under the account of the process which calls
|
||
<a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a>. Specifically, if the process calling <a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a> runs
|
||
on a multi-user machine where users cannot trust each other, then a
|
||
malicious user could arrange to run essentially arbitrary code in a
|
||
victim user’s process, simply by connecting to the victim’s
|
||
<a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a> socket and sending a configuration which runs whatever
|
||
code the attacker wants to have executed in the victim’s process. This is
|
||
especially easy to do if the default port is used, but not hard even if a
|
||
different port is used. To avoid the risk of this happening, use the
|
||
<code class="docutils literal notranslate"><span class="pre">verify</span></code> argument to <a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a> to prevent unrecognised
|
||
configurations from being applied.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.4: </span>The <code class="docutils literal notranslate"><span class="pre">verify</span></code> argument was added.</p>
|
||
</div>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>If you want to send configurations to the listener which don’t
|
||
disable existing loggers, you will need to use a JSON format for
|
||
the configuration, which will use <a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a> for configuration.
|
||
This method allows you to specify <code class="docutils literal notranslate"><span class="pre">disable_existing_loggers</span></code> as
|
||
<code class="docutils literal notranslate"><span class="pre">False</span></code> in the configuration you send.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py function">
|
||
<dt class="sig sig-object py" id="logging.config.stopListening">
|
||
<span class="sig-prename descclassname"><span class="pre">logging.config.</span></span><span class="sig-name descname"><span class="pre">stopListening</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#logging.config.stopListening" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Stops the listening server which was created with a call to <a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a>.
|
||
This is typically called before calling <code class="xref py py-meth docutils literal notranslate"><span class="pre">join()</span></code> on the return value from
|
||
<a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a>.</p>
|
||
</dd></dl>
|
||
|
||
</section>
|
||
<section id="security-considerations">
|
||
<h2>Security considerations<a class="headerlink" href="#security-considerations" title="Link to this heading">¶</a></h2>
|
||
<p>The logging configuration functionality tries to offer convenience, and in part this
|
||
is done by offering the ability to convert text in configuration files into Python
|
||
objects used in logging configuration - for example, as described in
|
||
<a class="reference internal" href="#logging-config-dict-userdef"><span class="std std-ref">User-defined objects</span></a>. However, these same mechanisms (importing
|
||
callables from user-defined modules and calling them with parameters from the
|
||
configuration) could be used to invoke any code you like, and for this reason you
|
||
should treat configuration files from untrusted sources with <em>extreme caution</em> and
|
||
satisfy yourself that nothing bad can happen if you load them, before actually loading
|
||
them.</p>
|
||
</section>
|
||
<section id="configuration-dictionary-schema">
|
||
<span id="logging-config-dictschema"></span><h2>Configuration dictionary schema<a class="headerlink" href="#configuration-dictionary-schema" title="Link to this heading">¶</a></h2>
|
||
<p>Describing a logging configuration requires listing the various
|
||
objects to create and the connections between them; for example, you
|
||
may create a handler named ‘console’ and then say that the logger
|
||
named ‘startup’ will send its messages to the ‘console’ handler.
|
||
These objects aren’t limited to those provided by the <a class="reference internal" href="logging.html#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code></a>
|
||
module because you might write your own formatter or handler class.
|
||
The parameters to these classes may also need to include external
|
||
objects such as <code class="docutils literal notranslate"><span class="pre">sys.stderr</span></code>. The syntax for describing these
|
||
objects and connections is defined in <a class="reference internal" href="#logging-config-dict-connections"><span class="std std-ref">Object connections</span></a>
|
||
below.</p>
|
||
<section id="dictionary-schema-details">
|
||
<h3>Dictionary Schema Details<a class="headerlink" href="#dictionary-schema-details" title="Link to this heading">¶</a></h3>
|
||
<p>The dictionary passed to <a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a> must contain the following
|
||
keys:</p>
|
||
<ul class="simple">
|
||
<li><p><em>version</em> - to be set to an integer value representing the schema
|
||
version. The only valid value at present is 1, but having this key
|
||
allows the schema to evolve while still preserving backwards
|
||
compatibility.</p></li>
|
||
</ul>
|
||
<p>All other keys are optional, but if present they will be interpreted
|
||
as described below. In all cases below where a ‘configuring dict’ is
|
||
mentioned, it will be checked for the special <code class="docutils literal notranslate"><span class="pre">'()'</span></code> key to see if a
|
||
custom instantiation is required. If so, the mechanism described in
|
||
<a class="reference internal" href="#logging-config-dict-userdef"><span class="std std-ref">User-defined objects</span></a> below is used to create an instance;
|
||
otherwise, the context is used to determine what to instantiate.</p>
|
||
<ul id="logging-config-dictschema-formatters">
|
||
<li><p><em>formatters</em> - the corresponding value will be a dict in which each
|
||
key is a formatter id and each value is a dict describing how to
|
||
configure the corresponding <a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Formatter</span></code></a> instance.</p>
|
||
<p>The configuring dict is searched for the following optional keys
|
||
which correspond to the arguments passed to create a
|
||
<a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Formatter</span></code></a> object:</p>
|
||
<ul class="simple">
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">format</span></code></p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">datefmt</span></code></p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">style</span></code></p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">validate</span></code> (since version >=3.8)</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">defaults</span></code> (since version >=3.12)</p></li>
|
||
</ul>
|
||
<p>An optional <code class="docutils literal notranslate"><span class="pre">class</span></code> key indicates the name of the formatter’s
|
||
class (as a dotted module and class name). The instantiation
|
||
arguments are as for <a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Formatter</span></code></a>, thus this key is
|
||
most useful for instantiating a customised subclass of
|
||
<a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Formatter</span></code></a>. For example, the alternative class
|
||
might present exception tracebacks in an expanded or condensed
|
||
format. If your formatter requires different or extra configuration
|
||
keys, you should use <a class="reference internal" href="#logging-config-dict-userdef"><span class="std std-ref">User-defined objects</span></a>.</p>
|
||
</li>
|
||
<li><p><em>filters</em> - the corresponding value will be a dict in which each key
|
||
is a filter id and each value is a dict describing how to configure
|
||
the corresponding Filter instance.</p>
|
||
<p>The configuring dict is searched for the key <code class="docutils literal notranslate"><span class="pre">name</span></code> (defaulting to the
|
||
empty string) and this is used to construct a <a class="reference internal" href="logging.html#logging.Filter" title="logging.Filter"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.Filter</span></code></a>
|
||
instance.</p>
|
||
</li>
|
||
<li><p><em>handlers</em> - the corresponding value will be a dict in which each
|
||
key is a handler id and each value is a dict describing how to
|
||
configure the corresponding Handler instance.</p>
|
||
<p>The configuring dict is searched for the following keys:</p>
|
||
<ul>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">class</span></code> (mandatory). This is the fully qualified name of the
|
||
handler class.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">level</span></code> (optional). The level of the handler.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">formatter</span></code> (optional). The id of the formatter for this
|
||
handler.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">filters</span></code> (optional). A list of ids of the filters for this
|
||
handler.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.11: </span><code class="docutils literal notranslate"><span class="pre">filters</span></code> can take filter instances in addition to ids.</p>
|
||
</div>
|
||
</li>
|
||
</ul>
|
||
<p>All <em>other</em> keys are passed through as keyword arguments to the
|
||
handler’s constructor. For example, given the snippet:</p>
|
||
<div class="highlight-yaml notranslate"><div class="highlight"><pre><span></span><span class="nt">handlers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">console</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">class </span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">logging.StreamHandler</span>
|
||
<span class="w"> </span><span class="nt">formatter</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">brief</span>
|
||
<span class="w"> </span><span class="nt">level </span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">INFO</span>
|
||
<span class="w"> </span><span class="nt">filters</span><span class="p">:</span><span class="w"> </span><span class="p p-Indicator">[</span><span class="nv">allow_foo</span><span class="p p-Indicator">]</span>
|
||
<span class="w"> </span><span class="nt">stream </span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">ext://sys.stdout</span>
|
||
<span class="w"> </span><span class="nt">file</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">class </span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">logging.handlers.RotatingFileHandler</span>
|
||
<span class="w"> </span><span class="nt">formatter</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">precise</span>
|
||
<span class="w"> </span><span class="nt">filename</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">logconfig.log</span>
|
||
<span class="w"> </span><span class="nt">maxBytes</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">1024</span>
|
||
<span class="w"> </span><span class="nt">backupCount</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">3</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>the handler with id <code class="docutils literal notranslate"><span class="pre">console</span></code> is instantiated as a
|
||
<a class="reference internal" href="logging.handlers.html#logging.StreamHandler" title="logging.StreamHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.StreamHandler</span></code></a>, using <code class="docutils literal notranslate"><span class="pre">sys.stdout</span></code> as the underlying
|
||
stream. The handler with id <code class="docutils literal notranslate"><span class="pre">file</span></code> is instantiated as a
|
||
<a class="reference internal" href="logging.handlers.html#logging.handlers.RotatingFileHandler" title="logging.handlers.RotatingFileHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.handlers.RotatingFileHandler</span></code></a> with the keyword arguments
|
||
<code class="docutils literal notranslate"><span class="pre">filename='logconfig.log',</span> <span class="pre">maxBytes=1024,</span> <span class="pre">backupCount=3</span></code>.</p>
|
||
</li>
|
||
<li><p><em>loggers</em> - the corresponding value will be a dict in which each key
|
||
is a logger name and each value is a dict describing how to
|
||
configure the corresponding Logger instance.</p>
|
||
<p>The configuring dict is searched for the following keys:</p>
|
||
<ul>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">level</span></code> (optional). The level of the logger.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">propagate</span></code> (optional). The propagation setting of the logger.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">filters</span></code> (optional). A list of ids of the filters for this
|
||
logger.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.11: </span><code class="docutils literal notranslate"><span class="pre">filters</span></code> can take filter instances in addition to ids.</p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">handlers</span></code> (optional). A list of ids of the handlers for this
|
||
logger.</p></li>
|
||
</ul>
|
||
<p>The specified loggers will be configured according to the level,
|
||
propagation, filters and handlers specified.</p>
|
||
</li>
|
||
<li><p><em>root</em> - this will be the configuration for the root logger.
|
||
Processing of the configuration will be as for any logger, except
|
||
that the <code class="docutils literal notranslate"><span class="pre">propagate</span></code> setting will not be applicable.</p></li>
|
||
<li><p><em>incremental</em> - whether the configuration is to be interpreted as
|
||
incremental to the existing configuration. This value defaults to
|
||
<code class="docutils literal notranslate"><span class="pre">False</span></code>, which means that the specified configuration replaces the
|
||
existing configuration with the same semantics as used by the
|
||
existing <a class="reference internal" href="#logging.config.fileConfig" title="logging.config.fileConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">fileConfig()</span></code></a> API.</p>
|
||
<p>If the specified value is <code class="docutils literal notranslate"><span class="pre">True</span></code>, the configuration is processed
|
||
as described in the section on <a class="reference internal" href="#logging-config-dict-incremental"><span class="std std-ref">Incremental Configuration</span></a>.</p>
|
||
</li>
|
||
<li><p><em>disable_existing_loggers</em> - whether any existing non-root loggers are
|
||
to be disabled. This setting mirrors the parameter of the same name in
|
||
<a class="reference internal" href="#logging.config.fileConfig" title="logging.config.fileConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">fileConfig()</span></code></a>. If absent, this parameter defaults to <code class="docutils literal notranslate"><span class="pre">True</span></code>.
|
||
This value is ignored if <em>incremental</em> is <code class="docutils literal notranslate"><span class="pre">True</span></code>.</p></li>
|
||
</ul>
|
||
</section>
|
||
<section id="incremental-configuration">
|
||
<span id="logging-config-dict-incremental"></span><h3>Incremental Configuration<a class="headerlink" href="#incremental-configuration" title="Link to this heading">¶</a></h3>
|
||
<p>It is difficult to provide complete flexibility for incremental
|
||
configuration. For example, because objects such as filters
|
||
and formatters are anonymous, once a configuration is set up, it is
|
||
not possible to refer to such anonymous objects when augmenting a
|
||
configuration.</p>
|
||
<p>Furthermore, there is not a compelling case for arbitrarily altering
|
||
the object graph of loggers, handlers, filters, formatters at
|
||
run-time, once a configuration is set up; the verbosity of loggers and
|
||
handlers can be controlled just by setting levels (and, in the case of
|
||
loggers, propagation flags). Changing the object graph arbitrarily in
|
||
a safe way is problematic in a multi-threaded environment; while not
|
||
impossible, the benefits are not worth the complexity it adds to the
|
||
implementation.</p>
|
||
<p>Thus, when the <code class="docutils literal notranslate"><span class="pre">incremental</span></code> key of a configuration dict is present
|
||
and is <code class="docutils literal notranslate"><span class="pre">True</span></code>, the system will completely ignore any <code class="docutils literal notranslate"><span class="pre">formatters</span></code> and
|
||
<code class="docutils literal notranslate"><span class="pre">filters</span></code> entries, and process only the <code class="docutils literal notranslate"><span class="pre">level</span></code>
|
||
settings in the <code class="docutils literal notranslate"><span class="pre">handlers</span></code> entries, and the <code class="docutils literal notranslate"><span class="pre">level</span></code> and
|
||
<code class="docutils literal notranslate"><span class="pre">propagate</span></code> settings in the <code class="docutils literal notranslate"><span class="pre">loggers</span></code> and <code class="docutils literal notranslate"><span class="pre">root</span></code> entries.</p>
|
||
<p>Using a value in the configuration dict lets configurations to be sent
|
||
over the wire as pickled dicts to a socket listener. Thus, the logging
|
||
verbosity of a long-running application can be altered over time with
|
||
no need to stop and restart the application.</p>
|
||
</section>
|
||
<section id="object-connections">
|
||
<span id="logging-config-dict-connections"></span><h3>Object connections<a class="headerlink" href="#object-connections" title="Link to this heading">¶</a></h3>
|
||
<p>The schema describes a set of logging objects - loggers,
|
||
handlers, formatters, filters - which are connected to each other in
|
||
an object graph. Thus, the schema needs to represent connections
|
||
between the objects. For example, say that, once configured, a
|
||
particular logger has attached to it a particular handler. For the
|
||
purposes of this discussion, we can say that the logger represents the
|
||
source, and the handler the destination, of a connection between the
|
||
two. Of course in the configured objects this is represented by the
|
||
logger holding a reference to the handler. In the configuration dict,
|
||
this is done by giving each destination object an id which identifies
|
||
it unambiguously, and then using the id in the source object’s
|
||
configuration to indicate that a connection exists between the source
|
||
and the destination object with that id.</p>
|
||
<p>So, for example, consider the following YAML snippet:</p>
|
||
<div class="highlight-yaml notranslate"><div class="highlight"><pre><span></span><span class="nt">formatters</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">brief</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="c1"># configuration for formatter with id 'brief' goes here</span>
|
||
<span class="w"> </span><span class="nt">precise</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="c1"># configuration for formatter with id 'precise' goes here</span>
|
||
<span class="nt">handlers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">h1</span><span class="p">:</span><span class="w"> </span><span class="c1">#This is an id</span>
|
||
<span class="w"> </span><span class="c1"># configuration of handler with id 'h1' goes here</span>
|
||
<span class="w"> </span><span class="nt">formatter</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">brief</span>
|
||
<span class="w"> </span><span class="nt">h2</span><span class="p">:</span><span class="w"> </span><span class="c1">#This is another id</span>
|
||
<span class="w"> </span><span class="c1"># configuration of handler with id 'h2' goes here</span>
|
||
<span class="w"> </span><span class="nt">formatter</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">precise</span>
|
||
<span class="nt">loggers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">foo.bar.baz</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="c1"># other configuration for logger 'foo.bar.baz'</span>
|
||
<span class="w"> </span><span class="nt">handlers</span><span class="p">:</span><span class="w"> </span><span class="p p-Indicator">[</span><span class="nv">h1</span><span class="p p-Indicator">,</span><span class="w"> </span><span class="nv">h2</span><span class="p p-Indicator">]</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>(Note: YAML used here because it’s a little more readable than the
|
||
equivalent Python source form for the dictionary.)</p>
|
||
<p>The ids for loggers are the logger names which would be used
|
||
programmatically to obtain a reference to those loggers, e.g.
|
||
<code class="docutils literal notranslate"><span class="pre">foo.bar.baz</span></code>. The ids for Formatters and Filters can be any string
|
||
value (such as <code class="docutils literal notranslate"><span class="pre">brief</span></code>, <code class="docutils literal notranslate"><span class="pre">precise</span></code> above) and they are transient,
|
||
in that they are only meaningful for processing the configuration
|
||
dictionary and used to determine connections between objects, and are
|
||
not persisted anywhere when the configuration call is complete.</p>
|
||
<p>The above snippet indicates that logger named <code class="docutils literal notranslate"><span class="pre">foo.bar.baz</span></code> should
|
||
have two handlers attached to it, which are described by the handler
|
||
ids <code class="docutils literal notranslate"><span class="pre">h1</span></code> and <code class="docutils literal notranslate"><span class="pre">h2</span></code>. The formatter for <code class="docutils literal notranslate"><span class="pre">h1</span></code> is that described by id
|
||
<code class="docutils literal notranslate"><span class="pre">brief</span></code>, and the formatter for <code class="docutils literal notranslate"><span class="pre">h2</span></code> is that described by id
|
||
<code class="docutils literal notranslate"><span class="pre">precise</span></code>.</p>
|
||
</section>
|
||
<section id="user-defined-objects">
|
||
<span id="logging-config-dict-userdef"></span><h3>User-defined objects<a class="headerlink" href="#user-defined-objects" title="Link to this heading">¶</a></h3>
|
||
<p>The schema supports user-defined objects for handlers, filters and
|
||
formatters. (Loggers do not need to have different types for
|
||
different instances, so there is no support in this configuration
|
||
schema for user-defined logger classes.)</p>
|
||
<p>Objects to be configured are described by dictionaries
|
||
which detail their configuration. In some places, the logging system
|
||
will be able to infer from the context how an object is to be
|
||
instantiated, but when a user-defined object is to be instantiated,
|
||
the system will not know how to do this. In order to provide complete
|
||
flexibility for user-defined object instantiation, the user needs
|
||
to provide a ‘factory’ - a callable which is called with a
|
||
configuration dictionary and which returns the instantiated object.
|
||
This is signalled by an absolute import path to the factory being
|
||
made available under the special key <code class="docutils literal notranslate"><span class="pre">'()'</span></code>. Here’s a concrete
|
||
example:</p>
|
||
<div class="highlight-yaml notranslate"><div class="highlight"><pre><span></span><span class="nt">formatters</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">brief</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">format</span><span class="p">:</span><span class="w"> </span><span class="s">'%(message)s'</span>
|
||
<span class="w"> </span><span class="nt">default</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">format</span><span class="p">:</span><span class="w"> </span><span class="s">'%(asctime)s</span><span class="nv"> </span><span class="s">%(levelname)-8s</span><span class="nv"> </span><span class="s">%(name)-15s</span><span class="nv"> </span><span class="s">%(message)s'</span>
|
||
<span class="w"> </span><span class="nt">datefmt</span><span class="p">:</span><span class="w"> </span><span class="s">'%Y-%m-%d</span><span class="nv"> </span><span class="s">%H:%M:%S'</span>
|
||
<span class="w"> </span><span class="nt">custom</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">()</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">my.package.customFormatterFactory</span>
|
||
<span class="w"> </span><span class="nt">bar</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">baz</span>
|
||
<span class="w"> </span><span class="nt">spam</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">99.9</span>
|
||
<span class="w"> </span><span class="nt">answer</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">42</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The above YAML snippet defines three formatters. The first, with id
|
||
<code class="docutils literal notranslate"><span class="pre">brief</span></code>, is a standard <a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.Formatter</span></code></a> instance with the
|
||
specified format string. The second, with id <code class="docutils literal notranslate"><span class="pre">default</span></code>, has a
|
||
longer format and also defines the time format explicitly, and will
|
||
result in a <a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.Formatter</span></code></a> initialized with those two format
|
||
strings. Shown in Python source form, the <code class="docutils literal notranslate"><span class="pre">brief</span></code> and <code class="docutils literal notranslate"><span class="pre">default</span></code>
|
||
formatters have configuration sub-dictionaries:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">{</span>
|
||
<span class="s1">'format'</span> <span class="p">:</span> <span class="s1">'</span><span class="si">%(message)s</span><span class="s1">'</span>
|
||
<span class="p">}</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>and:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">{</span>
|
||
<span class="s1">'format'</span> <span class="p">:</span> <span class="s1">'</span><span class="si">%(asctime)s</span><span class="s1"> </span><span class="si">%(levelname)-8s</span><span class="s1"> </span><span class="si">%(name)-15s</span><span class="s1"> </span><span class="si">%(message)s</span><span class="s1">'</span><span class="p">,</span>
|
||
<span class="s1">'datefmt'</span> <span class="p">:</span> <span class="s1">'%Y-%m-</span><span class="si">%d</span><span class="s1"> %H:%M:%S'</span>
|
||
<span class="p">}</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>respectively, and as these dictionaries do not contain the special key
|
||
<code class="docutils literal notranslate"><span class="pre">'()'</span></code>, the instantiation is inferred from the context: as a result,
|
||
standard <a class="reference internal" href="logging.html#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.Formatter</span></code></a> instances are created. The
|
||
configuration sub-dictionary for the third formatter, with id
|
||
<code class="docutils literal notranslate"><span class="pre">custom</span></code>, is:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">{</span>
|
||
<span class="s1">'()'</span> <span class="p">:</span> <span class="s1">'my.package.customFormatterFactory'</span><span class="p">,</span>
|
||
<span class="s1">'bar'</span> <span class="p">:</span> <span class="s1">'baz'</span><span class="p">,</span>
|
||
<span class="s1">'spam'</span> <span class="p">:</span> <span class="mf">99.9</span><span class="p">,</span>
|
||
<span class="s1">'answer'</span> <span class="p">:</span> <span class="mi">42</span>
|
||
<span class="p">}</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>and this contains the special key <code class="docutils literal notranslate"><span class="pre">'()'</span></code>, which means that
|
||
user-defined instantiation is wanted. In this case, the specified
|
||
factory callable will be used. If it is an actual callable it will be
|
||
used directly - otherwise, if you specify a string (as in the example)
|
||
the actual callable will be located using normal import mechanisms.
|
||
The callable will be called with the <strong>remaining</strong> items in the
|
||
configuration sub-dictionary as keyword arguments. In the above
|
||
example, the formatter with id <code class="docutils literal notranslate"><span class="pre">custom</span></code> will be assumed to be
|
||
returned by the call:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">my</span><span class="o">.</span><span class="n">package</span><span class="o">.</span><span class="n">customFormatterFactory</span><span class="p">(</span><span class="n">bar</span><span class="o">=</span><span class="s1">'baz'</span><span class="p">,</span> <span class="n">spam</span><span class="o">=</span><span class="mf">99.9</span><span class="p">,</span> <span class="n">answer</span><span class="o">=</span><span class="mi">42</span><span class="p">)</span>
|
||
</pre></div>
|
||
</div>
|
||
<div class="admonition warning">
|
||
<p class="admonition-title">Warning</p>
|
||
<p>The values for keys such as <code class="docutils literal notranslate"><span class="pre">bar</span></code>, <code class="docutils literal notranslate"><span class="pre">spam</span></code> and <code class="docutils literal notranslate"><span class="pre">answer</span></code> in
|
||
the above example should not be configuration dictionaries or references such
|
||
as <code class="docutils literal notranslate"><span class="pre">cfg://foo</span></code> or <code class="docutils literal notranslate"><span class="pre">ext://bar</span></code>, because they will not be processed by the
|
||
configuration machinery, but passed to the callable as-is.</p>
|
||
</div>
|
||
<p>The key <code class="docutils literal notranslate"><span class="pre">'()'</span></code> has been used as the special key because it is not a
|
||
valid keyword parameter name, and so will not clash with the names of
|
||
the keyword arguments used in the call. The <code class="docutils literal notranslate"><span class="pre">'()'</span></code> also serves as a
|
||
mnemonic that the corresponding value is a callable.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.11: </span>The <code class="docutils literal notranslate"><span class="pre">filters</span></code> member of <code class="docutils literal notranslate"><span class="pre">handlers</span></code> and <code class="docutils literal notranslate"><span class="pre">loggers</span></code> can take
|
||
filter instances in addition to ids.</p>
|
||
</div>
|
||
<p>You can also specify a special key <code class="docutils literal notranslate"><span class="pre">'.'</span></code> whose value is a dictionary is a
|
||
mapping of attribute names to values. If found, the specified attributes will
|
||
be set on the user-defined object before it is returned. Thus, with the
|
||
following configuration:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">{</span>
|
||
<span class="s1">'()'</span> <span class="p">:</span> <span class="s1">'my.package.customFormatterFactory'</span><span class="p">,</span>
|
||
<span class="s1">'bar'</span> <span class="p">:</span> <span class="s1">'baz'</span><span class="p">,</span>
|
||
<span class="s1">'spam'</span> <span class="p">:</span> <span class="mf">99.9</span><span class="p">,</span>
|
||
<span class="s1">'answer'</span> <span class="p">:</span> <span class="mi">42</span><span class="p">,</span>
|
||
<span class="s1">'.'</span> <span class="p">{</span>
|
||
<span class="s1">'foo'</span><span class="p">:</span> <span class="s1">'bar'</span><span class="p">,</span>
|
||
<span class="s1">'baz'</span><span class="p">:</span> <span class="s1">'bozz'</span>
|
||
<span class="p">}</span>
|
||
<span class="p">}</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>the returned formatter will have attribute <code class="docutils literal notranslate"><span class="pre">foo</span></code> set to <code class="docutils literal notranslate"><span class="pre">'bar'</span></code> and
|
||
attribute <code class="docutils literal notranslate"><span class="pre">baz</span></code> set to <code class="docutils literal notranslate"><span class="pre">'bozz'</span></code>.</p>
|
||
<div class="admonition warning">
|
||
<p class="admonition-title">Warning</p>
|
||
<p>The values for attributes such as <code class="docutils literal notranslate"><span class="pre">foo</span></code> and <code class="docutils literal notranslate"><span class="pre">baz</span></code> in
|
||
the above example should not be configuration dictionaries or references such
|
||
as <code class="docutils literal notranslate"><span class="pre">cfg://foo</span></code> or <code class="docutils literal notranslate"><span class="pre">ext://bar</span></code>, because they will not be processed by the
|
||
configuration machinery, but set as attribute values as-is.</p>
|
||
</div>
|
||
</section>
|
||
<section id="handler-configuration-order">
|
||
<span id="handler-config-dict-order"></span><h3>Handler configuration order<a class="headerlink" href="#handler-configuration-order" title="Link to this heading">¶</a></h3>
|
||
<p>Handlers are configured in alphabetical order of their keys, and a configured
|
||
handler replaces the configuration dictionary in (a working copy of) the
|
||
<code class="docutils literal notranslate"><span class="pre">handlers</span></code> dictionary in the schema. If you use a construct such as
|
||
<code class="docutils literal notranslate"><span class="pre">cfg://handlers.foo</span></code>, then initially <code class="docutils literal notranslate"><span class="pre">handlers['foo']</span></code> points to the
|
||
configuration dictionary for the handler named <code class="docutils literal notranslate"><span class="pre">foo</span></code>, and later (once that
|
||
handler has been configured) it points to the configured handler instance.
|
||
Thus, <code class="docutils literal notranslate"><span class="pre">cfg://handlers.foo</span></code> could resolve to either a dictionary or a handler
|
||
instance. In general, it is wise to name handlers in a way such that dependent
|
||
handlers are configured _after_ any handlers they depend on; that allows
|
||
something like <code class="docutils literal notranslate"><span class="pre">cfg://handlers.foo</span></code> to be used in configuring a handler that
|
||
depends on handler <code class="docutils literal notranslate"><span class="pre">foo</span></code>. If that dependent handler were named <code class="docutils literal notranslate"><span class="pre">bar</span></code>,
|
||
problems would result, because the configuration of <code class="docutils literal notranslate"><span class="pre">bar</span></code> would be attempted
|
||
before that of <code class="docutils literal notranslate"><span class="pre">foo</span></code>, and <code class="docutils literal notranslate"><span class="pre">foo</span></code> would not yet have been configured.
|
||
However, if the dependent handler were named <code class="docutils literal notranslate"><span class="pre">foobar</span></code>, it would be configured
|
||
after <code class="docutils literal notranslate"><span class="pre">foo</span></code>, with the result that <code class="docutils literal notranslate"><span class="pre">cfg://handlers.foo</span></code> would resolve to
|
||
configured handler <code class="docutils literal notranslate"><span class="pre">foo</span></code>, and not its configuration dictionary.</p>
|
||
</section>
|
||
<section id="access-to-external-objects">
|
||
<span id="logging-config-dict-externalobj"></span><h3>Access to external objects<a class="headerlink" href="#access-to-external-objects" title="Link to this heading">¶</a></h3>
|
||
<p>There are times where a configuration needs to refer to objects
|
||
external to the configuration, for example <code class="docutils literal notranslate"><span class="pre">sys.stderr</span></code>. If the
|
||
configuration dict is constructed using Python code, this is
|
||
straightforward, but a problem arises when the configuration is
|
||
provided via a text file (e.g. JSON, YAML). In a text file, there is
|
||
no standard way to distinguish <code class="docutils literal notranslate"><span class="pre">sys.stderr</span></code> from the literal string
|
||
<code class="docutils literal notranslate"><span class="pre">'sys.stderr'</span></code>. To facilitate this distinction, the configuration
|
||
system looks for certain special prefixes in string values and
|
||
treat them specially. For example, if the literal string
|
||
<code class="docutils literal notranslate"><span class="pre">'ext://sys.stderr'</span></code> is provided as a value in the configuration,
|
||
then the <code class="docutils literal notranslate"><span class="pre">ext://</span></code> will be stripped off and the remainder of the
|
||
value processed using normal import mechanisms.</p>
|
||
<p>The handling of such prefixes is done in a way analogous to protocol
|
||
handling: there is a generic mechanism to look for prefixes which
|
||
match the regular expression <code class="docutils literal notranslate"><span class="pre">^(?P<prefix>[a-z]+)://(?P<suffix>.*)$</span></code>
|
||
whereby, if the <code class="docutils literal notranslate"><span class="pre">prefix</span></code> is recognised, the <code class="docutils literal notranslate"><span class="pre">suffix</span></code> is processed
|
||
in a prefix-dependent manner and the result of the processing replaces
|
||
the string value. If the prefix is not recognised, then the string
|
||
value will be left as-is.</p>
|
||
</section>
|
||
<section id="access-to-internal-objects">
|
||
<span id="logging-config-dict-internalobj"></span><h3>Access to internal objects<a class="headerlink" href="#access-to-internal-objects" title="Link to this heading">¶</a></h3>
|
||
<p>As well as external objects, there is sometimes also a need to refer
|
||
to objects in the configuration. This will be done implicitly by the
|
||
configuration system for things that it knows about. For example, the
|
||
string value <code class="docutils literal notranslate"><span class="pre">'DEBUG'</span></code> for a <code class="docutils literal notranslate"><span class="pre">level</span></code> in a logger or handler will
|
||
automatically be converted to the value <code class="docutils literal notranslate"><span class="pre">logging.DEBUG</span></code>, and the
|
||
<code class="docutils literal notranslate"><span class="pre">handlers</span></code>, <code class="docutils literal notranslate"><span class="pre">filters</span></code> and <code class="docutils literal notranslate"><span class="pre">formatter</span></code> entries will take an
|
||
object id and resolve to the appropriate destination object.</p>
|
||
<p>However, a more generic mechanism is needed for user-defined
|
||
objects which are not known to the <a class="reference internal" href="logging.html#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code></a> module. For
|
||
example, consider <a class="reference internal" href="logging.handlers.html#logging.handlers.MemoryHandler" title="logging.handlers.MemoryHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.handlers.MemoryHandler</span></code></a>, which takes
|
||
a <code class="docutils literal notranslate"><span class="pre">target</span></code> argument which is another handler to delegate to. Since
|
||
the system already knows about this class, then in the configuration,
|
||
the given <code class="docutils literal notranslate"><span class="pre">target</span></code> just needs to be the object id of the relevant
|
||
target handler, and the system will resolve to the handler from the
|
||
id. If, however, a user defines a <code class="docutils literal notranslate"><span class="pre">my.package.MyHandler</span></code> which has
|
||
an <code class="docutils literal notranslate"><span class="pre">alternate</span></code> handler, the configuration system would not know that
|
||
the <code class="docutils literal notranslate"><span class="pre">alternate</span></code> referred to a handler. To cater for this, a generic
|
||
resolution system allows the user to specify:</p>
|
||
<div class="highlight-yaml notranslate"><div class="highlight"><pre><span></span><span class="nt">handlers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">file</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="c1"># configuration of file handler goes here</span>
|
||
|
||
<span class="w"> </span><span class="nt">custom</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">()</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">my.package.MyHandler</span>
|
||
<span class="w"> </span><span class="nt">alternate</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">cfg://handlers.file</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The literal string <code class="docutils literal notranslate"><span class="pre">'cfg://handlers.file'</span></code> will be resolved in an
|
||
analogous way to strings with the <code class="docutils literal notranslate"><span class="pre">ext://</span></code> prefix, but looking
|
||
in the configuration itself rather than the import namespace. The
|
||
mechanism allows access by dot or by index, in a similar way to
|
||
that provided by <code class="docutils literal notranslate"><span class="pre">str.format</span></code>. Thus, given the following snippet:</p>
|
||
<div class="highlight-yaml notranslate"><div class="highlight"><pre><span></span><span class="nt">handlers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">email</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">class</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">logging.handlers.SMTPHandler</span>
|
||
<span class="w"> </span><span class="nt">mailhost</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">localhost</span>
|
||
<span class="w"> </span><span class="nt">fromaddr</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">my_app@domain.tld</span>
|
||
<span class="w"> </span><span class="nt">toaddrs</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="p p-Indicator">-</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">support_team@domain.tld</span>
|
||
<span class="w"> </span><span class="p p-Indicator">-</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">dev_team@domain.tld</span>
|
||
<span class="w"> </span><span class="nt">subject</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">Houston, we have a problem.</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>in the configuration, the string <code class="docutils literal notranslate"><span class="pre">'cfg://handlers'</span></code> would resolve to
|
||
the dict with key <code class="docutils literal notranslate"><span class="pre">handlers</span></code>, the string <code class="docutils literal notranslate"><span class="pre">'cfg://handlers.email</span></code>
|
||
would resolve to the dict with key <code class="docutils literal notranslate"><span class="pre">email</span></code> in the <code class="docutils literal notranslate"><span class="pre">handlers</span></code> dict,
|
||
and so on. The string <code class="docutils literal notranslate"><span class="pre">'cfg://handlers.email.toaddrs[1]</span></code> would
|
||
resolve to <code class="docutils literal notranslate"><span class="pre">'dev_team@domain.tld'</span></code> and the string
|
||
<code class="docutils literal notranslate"><span class="pre">'cfg://handlers.email.toaddrs[0]'</span></code> would resolve to the value
|
||
<code class="docutils literal notranslate"><span class="pre">'support_team@domain.tld'</span></code>. The <code class="docutils literal notranslate"><span class="pre">subject</span></code> value could be accessed
|
||
using either <code class="docutils literal notranslate"><span class="pre">'cfg://handlers.email.subject'</span></code> or, equivalently,
|
||
<code class="docutils literal notranslate"><span class="pre">'cfg://handlers.email[subject]'</span></code>. The latter form only needs to be
|
||
used if the key contains spaces or non-alphanumeric characters. Please note
|
||
that the characters <code class="docutils literal notranslate"><span class="pre">[</span></code> and <code class="docutils literal notranslate"><span class="pre">]</span></code> are not allowed in the keys. If an
|
||
index value consists only of decimal digits, access will be attempted
|
||
using the corresponding integer value, falling back to the string
|
||
value if needed.</p>
|
||
<p>Given a string <code class="docutils literal notranslate"><span class="pre">cfg://handlers.myhandler.mykey.123</span></code>, this will
|
||
resolve to <code class="docutils literal notranslate"><span class="pre">config_dict['handlers']['myhandler']['mykey']['123']</span></code>.
|
||
If the string is specified as <code class="docutils literal notranslate"><span class="pre">cfg://handlers.myhandler.mykey[123]</span></code>,
|
||
the system will attempt to retrieve the value from
|
||
<code class="docutils literal notranslate"><span class="pre">config_dict['handlers']['myhandler']['mykey'][123]</span></code>, and fall back
|
||
to <code class="docutils literal notranslate"><span class="pre">config_dict['handlers']['myhandler']['mykey']['123']</span></code> if that
|
||
fails.</p>
|
||
</section>
|
||
<section id="import-resolution-and-custom-importers">
|
||
<span id="logging-import-resolution"></span><h3>Import resolution and custom importers<a class="headerlink" href="#import-resolution-and-custom-importers" title="Link to this heading">¶</a></h3>
|
||
<p>Import resolution, by default, uses the builtin <a class="reference internal" href="functions.html#import__" title="__import__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__import__()</span></code></a> function
|
||
to do its importing. You may want to replace this with your own importing
|
||
mechanism: if so, you can replace the <code class="xref py py-attr docutils literal notranslate"><span class="pre">importer</span></code> attribute of the
|
||
<code class="xref py py-class docutils literal notranslate"><span class="pre">DictConfigurator</span></code> or its superclass, the
|
||
<code class="xref py py-class docutils literal notranslate"><span class="pre">BaseConfigurator</span></code> class. However, you need to be
|
||
careful because of the way functions are accessed from classes via
|
||
descriptors. If you are using a Python callable to do your imports, and you
|
||
want to define it at class level rather than instance level, you need to wrap
|
||
it with <a class="reference internal" href="functions.html#staticmethod" title="staticmethod"><code class="xref py py-func docutils literal notranslate"><span class="pre">staticmethod()</span></code></a>. For example:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span><span class="w"> </span><span class="nn">importlib</span><span class="w"> </span><span class="kn">import</span> <span class="n">import_module</span>
|
||
<span class="kn">from</span><span class="w"> </span><span class="nn">logging.config</span><span class="w"> </span><span class="kn">import</span> <span class="n">BaseConfigurator</span>
|
||
|
||
<span class="n">BaseConfigurator</span><span class="o">.</span><span class="n">importer</span> <span class="o">=</span> <span class="nb">staticmethod</span><span class="p">(</span><span class="n">import_module</span><span class="p">)</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>You don’t need to wrap with <a class="reference internal" href="functions.html#staticmethod" title="staticmethod"><code class="xref py py-func docutils literal notranslate"><span class="pre">staticmethod()</span></code></a> if you’re setting the import
|
||
callable on a configurator <em>instance</em>.</p>
|
||
</section>
|
||
<section id="configuring-queuehandler-and-queuelistener">
|
||
<span id="configure-queue"></span><h3>Configuring QueueHandler and QueueListener<a class="headerlink" href="#configuring-queuehandler-and-queuelistener" title="Link to this heading">¶</a></h3>
|
||
<p>If you want to configure a <a class="reference internal" href="logging.handlers.html#logging.handlers.QueueHandler" title="logging.handlers.QueueHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">QueueHandler</span></code></a>, noting that this
|
||
is normally used in conjunction with a <a class="reference internal" href="logging.handlers.html#logging.handlers.QueueListener" title="logging.handlers.QueueListener"><code class="xref py py-class docutils literal notranslate"><span class="pre">QueueListener</span></code></a>, you
|
||
can configure both together. After the configuration, the <code class="docutils literal notranslate"><span class="pre">QueueListener</span></code> instance
|
||
will be available as the <a class="reference internal" href="logging.handlers.html#logging.handlers.QueueHandler.listener" title="logging.handlers.QueueHandler.listener"><code class="xref py py-attr docutils literal notranslate"><span class="pre">listener</span></code></a> attribute of
|
||
the created handler, and that in turn will be available to you using
|
||
<a class="reference internal" href="logging.html#logging.getHandlerByName" title="logging.getHandlerByName"><code class="xref py py-func docutils literal notranslate"><span class="pre">getHandlerByName()</span></code></a> and passing the name you have used for the
|
||
<code class="docutils literal notranslate"><span class="pre">QueueHandler</span></code> in your configuration. The dictionary schema for configuring the pair
|
||
is shown in the example YAML snippet below.</p>
|
||
<div class="highlight-yaml notranslate"><div class="highlight"><pre><span></span><span class="nt">handlers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">qhand</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="nt">class</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">logging.handlers.QueueHandler</span>
|
||
<span class="w"> </span><span class="nt">queue</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">my.module.queue_factory</span>
|
||
<span class="w"> </span><span class="nt">listener</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">my.package.CustomListener</span>
|
||
<span class="w"> </span><span class="nt">handlers</span><span class="p">:</span>
|
||
<span class="w"> </span><span class="p p-Indicator">-</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">hand_name_1</span>
|
||
<span class="w"> </span><span class="p p-Indicator">-</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">hand_name_2</span>
|
||
<span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">...</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">queue</span></code> and <code class="docutils literal notranslate"><span class="pre">listener</span></code> keys are optional.</p>
|
||
<p>If the <code class="docutils literal notranslate"><span class="pre">queue</span></code> key is present, the corresponding value can be one of the following:</p>
|
||
<ul>
|
||
<li><p>An object implementing the <a class="reference internal" href="queue.html#queue.Queue.put_nowait" title="queue.Queue.put_nowait"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Queue.put_nowait</span></code></a>
|
||
and <a class="reference internal" href="queue.html#queue.Queue.get" title="queue.Queue.get"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Queue.get</span></code></a> public API. For instance, this may be
|
||
an actual instance of <a class="reference internal" href="queue.html#queue.Queue" title="queue.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">queue.Queue</span></code></a> or a subclass thereof, or a proxy
|
||
obtained by <a class="reference internal" href="multiprocessing.html#multiprocessing.managers.SyncManager.Queue" title="multiprocessing.managers.SyncManager.Queue"><code class="xref py py-meth docutils literal notranslate"><span class="pre">multiprocessing.managers.SyncManager.Queue()</span></code></a>.</p>
|
||
<p>This is of course only possible if you are constructing or modifying
|
||
the configuration dictionary in code.</p>
|
||
</li>
|
||
<li><p>A string that resolves to a callable which, when called with no arguments, returns
|
||
the queue instance to use. That callable could be a <a class="reference internal" href="queue.html#queue.Queue" title="queue.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">queue.Queue</span></code></a> subclass
|
||
or a function which returns a suitable queue instance,
|
||
such as <code class="docutils literal notranslate"><span class="pre">my.module.queue_factory()</span></code>.</p></li>
|
||
<li><p>A dict with a <code class="docutils literal notranslate"><span class="pre">'()'</span></code> key which is constructed in the usual way as discussed in
|
||
<a class="reference internal" href="#logging-config-dict-userdef"><span class="std std-ref">User-defined objects</span></a>. The result of this construction should be a
|
||
<a class="reference internal" href="queue.html#queue.Queue" title="queue.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">queue.Queue</span></code></a> instance.</p></li>
|
||
</ul>
|
||
<p>If the <code class="docutils literal notranslate"><span class="pre">queue</span></code> key is absent, a standard unbounded <a class="reference internal" href="queue.html#queue.Queue" title="queue.Queue"><code class="xref py py-class docutils literal notranslate"><span class="pre">queue.Queue</span></code></a> instance is
|
||
created and used.</p>
|
||
<p>If the <code class="docutils literal notranslate"><span class="pre">listener</span></code> key is present, the corresponding value can be one of the following:</p>
|
||
<ul class="simple">
|
||
<li><p>A subclass of <a class="reference internal" href="logging.handlers.html#logging.handlers.QueueListener" title="logging.handlers.QueueListener"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.handlers.QueueListener</span></code></a>. This is of course only
|
||
possible if you are constructing or modifying the configuration dictionary in
|
||
code.</p></li>
|
||
<li><p>A string which resolves to a class which is a subclass of <code class="docutils literal notranslate"><span class="pre">QueueListener</span></code>, such as
|
||
<code class="docutils literal notranslate"><span class="pre">'my.package.CustomListener'</span></code>.</p></li>
|
||
<li><p>A dict with a <code class="docutils literal notranslate"><span class="pre">'()'</span></code> key which is constructed in the usual way as discussed in
|
||
<a class="reference internal" href="#logging-config-dict-userdef"><span class="std std-ref">User-defined objects</span></a>. The result of this construction should be a
|
||
callable with the same signature as the <code class="docutils literal notranslate"><span class="pre">QueueListener</span></code> initializer.</p></li>
|
||
</ul>
|
||
<p>If the <code class="docutils literal notranslate"><span class="pre">listener</span></code> key is absent, <a class="reference internal" href="logging.handlers.html#logging.handlers.QueueListener" title="logging.handlers.QueueListener"><code class="xref py py-class docutils literal notranslate"><span class="pre">logging.handlers.QueueListener</span></code></a> is used.</p>
|
||
<p>The values under the <code class="docutils literal notranslate"><span class="pre">handlers</span></code> key are the names of other handlers in the
|
||
configuration (not shown in the above snippet) which will be passed to the queue
|
||
listener.</p>
|
||
<p>Any custom queue handler and listener classes will need to be defined with the same
|
||
initialization signatures as <a class="reference internal" href="logging.handlers.html#logging.handlers.QueueHandler" title="logging.handlers.QueueHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">QueueHandler</span></code></a> and
|
||
<a class="reference internal" href="logging.handlers.html#logging.handlers.QueueListener" title="logging.handlers.QueueListener"><code class="xref py py-class docutils literal notranslate"><span class="pre">QueueListener</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.12.</span></p>
|
||
</div>
|
||
</section>
|
||
</section>
|
||
<section id="configuration-file-format">
|
||
<span id="logging-config-fileformat"></span><h2>Configuration file format<a class="headerlink" href="#configuration-file-format" title="Link to this heading">¶</a></h2>
|
||
<p>The configuration file format understood by <a class="reference internal" href="#logging.config.fileConfig" title="logging.config.fileConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">fileConfig()</span></code></a> is based on
|
||
<a class="reference internal" href="configparser.html#module-configparser" title="configparser: Configuration file parser."><code class="xref py py-mod docutils literal notranslate"><span class="pre">configparser</span></code></a> functionality. The file must contain sections called
|
||
<code class="docutils literal notranslate"><span class="pre">[loggers]</span></code>, <code class="docutils literal notranslate"><span class="pre">[handlers]</span></code> and <code class="docutils literal notranslate"><span class="pre">[formatters]</span></code> which identify by name the
|
||
entities of each type which are defined in the file. For each such entity, there
|
||
is a separate section which identifies how that entity is configured. Thus, for
|
||
a logger named <code class="docutils literal notranslate"><span class="pre">log01</span></code> in the <code class="docutils literal notranslate"><span class="pre">[loggers]</span></code> section, the relevant
|
||
configuration details are held in a section <code class="docutils literal notranslate"><span class="pre">[logger_log01]</span></code>. Similarly, a
|
||
handler called <code class="docutils literal notranslate"><span class="pre">hand01</span></code> in the <code class="docutils literal notranslate"><span class="pre">[handlers]</span></code> section will have its
|
||
configuration held in a section called <code class="docutils literal notranslate"><span class="pre">[handler_hand01]</span></code>, while a formatter
|
||
called <code class="docutils literal notranslate"><span class="pre">form01</span></code> in the <code class="docutils literal notranslate"><span class="pre">[formatters]</span></code> section will have its configuration
|
||
specified in a section called <code class="docutils literal notranslate"><span class="pre">[formatter_form01]</span></code>. The root logger
|
||
configuration must be specified in a section called <code class="docutils literal notranslate"><span class="pre">[logger_root]</span></code>.</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>The <a class="reference internal" href="#logging.config.fileConfig" title="logging.config.fileConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">fileConfig()</span></code></a> API is older than the <a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a> API and does
|
||
not provide functionality to cover certain aspects of logging. For example,
|
||
you cannot configure <a class="reference internal" href="logging.html#logging.Filter" title="logging.Filter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Filter</span></code></a> objects, which provide for
|
||
filtering of messages beyond simple integer levels, using <a class="reference internal" href="#logging.config.fileConfig" title="logging.config.fileConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">fileConfig()</span></code></a>.
|
||
If you need to have instances of <a class="reference internal" href="logging.html#logging.Filter" title="logging.Filter"><code class="xref py py-class docutils literal notranslate"><span class="pre">Filter</span></code></a> in your logging
|
||
configuration, you will need to use <a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a>. Note that future
|
||
enhancements to configuration functionality will be added to
|
||
<a class="reference internal" href="#logging.config.dictConfig" title="logging.config.dictConfig"><code class="xref py py-func docutils literal notranslate"><span class="pre">dictConfig()</span></code></a>, so it’s worth considering transitioning to this newer
|
||
API when it’s convenient to do so.</p>
|
||
</div>
|
||
<p>Examples of these sections in the file are given below.</p>
|
||
<div class="highlight-ini notranslate"><div class="highlight"><pre><span></span><span class="k">[loggers]</span>
|
||
<span class="na">keys</span><span class="o">=</span><span class="s">root,log02,log03,log04,log05,log06,log07</span>
|
||
|
||
<span class="k">[handlers]</span>
|
||
<span class="na">keys</span><span class="o">=</span><span class="s">hand01,hand02,hand03,hand04,hand05,hand06,hand07,hand08,hand09</span>
|
||
|
||
<span class="k">[formatters]</span>
|
||
<span class="na">keys</span><span class="o">=</span><span class="s">form01,form02,form03,form04,form05,form06,form07,form08,form09</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The root logger must specify a level and a list of handlers. An example of a
|
||
root logger section is given below.</p>
|
||
<div class="highlight-ini notranslate"><div class="highlight"><pre><span></span><span class="k">[logger_root]</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">NOTSET</span>
|
||
<span class="na">handlers</span><span class="o">=</span><span class="s">hand01</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">level</span></code> entry can be one of <code class="docutils literal notranslate"><span class="pre">DEBUG,</span> <span class="pre">INFO,</span> <span class="pre">WARNING,</span> <span class="pre">ERROR,</span> <span class="pre">CRITICAL</span></code> or
|
||
<code class="docutils literal notranslate"><span class="pre">NOTSET</span></code>. For the root logger only, <code class="docutils literal notranslate"><span class="pre">NOTSET</span></code> means that all messages will be
|
||
logged. Level values are <a class="reference internal" href="functions.html#func-eval"><span class="std std-ref">evaluated</span></a> in the context of the <code class="docutils literal notranslate"><span class="pre">logging</span></code>
|
||
package’s namespace.</p>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">handlers</span></code> entry is a comma-separated list of handler names, which must
|
||
appear in the <code class="docutils literal notranslate"><span class="pre">[handlers]</span></code> section. These names must appear in the
|
||
<code class="docutils literal notranslate"><span class="pre">[handlers]</span></code> section and have corresponding sections in the configuration
|
||
file.</p>
|
||
<p>For loggers other than the root logger, some additional information is required.
|
||
This is illustrated by the following example.</p>
|
||
<div class="highlight-ini notranslate"><div class="highlight"><pre><span></span><span class="k">[logger_parser]</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">DEBUG</span>
|
||
<span class="na">handlers</span><span class="o">=</span><span class="s">hand01</span>
|
||
<span class="na">propagate</span><span class="o">=</span><span class="s">1</span>
|
||
<span class="na">qualname</span><span class="o">=</span><span class="s">compiler.parser</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">level</span></code> and <code class="docutils literal notranslate"><span class="pre">handlers</span></code> entries are interpreted as for the root logger,
|
||
except that if a non-root logger’s level is specified as <code class="docutils literal notranslate"><span class="pre">NOTSET</span></code>, the system
|
||
consults loggers higher up the hierarchy to determine the effective level of the
|
||
logger. The <code class="docutils literal notranslate"><span class="pre">propagate</span></code> entry is set to 1 to indicate that messages must
|
||
propagate to handlers higher up the logger hierarchy from this logger, or 0 to
|
||
indicate that messages are <strong>not</strong> propagated to handlers up the hierarchy. The
|
||
<code class="docutils literal notranslate"><span class="pre">qualname</span></code> entry is the hierarchical channel name of the logger, that is to
|
||
say the name used by the application to get the logger.</p>
|
||
<p>Sections which specify handler configuration are exemplified by the following.</p>
|
||
<div class="highlight-ini notranslate"><div class="highlight"><pre><span></span><span class="k">[handler_hand01]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">StreamHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">NOTSET</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form01</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">(sys.stdout,)</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">class</span></code> entry indicates the handler’s class (as determined by <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>
|
||
in the <code class="docutils literal notranslate"><span class="pre">logging</span></code> package’s namespace). The <code class="docutils literal notranslate"><span class="pre">level</span></code> is interpreted as for
|
||
loggers, and <code class="docutils literal notranslate"><span class="pre">NOTSET</span></code> is taken to mean ‘log everything’.</p>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">formatter</span></code> entry indicates the key name of the formatter for this
|
||
handler. If blank, a default formatter (<code class="docutils literal notranslate"><span class="pre">logging._defaultFormatter</span></code>) is used.
|
||
If a name is specified, it must appear in the <code class="docutils literal notranslate"><span class="pre">[formatters]</span></code> section and have
|
||
a corresponding section in the configuration file.</p>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">args</span></code> entry, when <a class="reference internal" href="functions.html#func-eval"><span class="std std-ref">evaluated</span></a> in the context of the <code class="docutils literal notranslate"><span class="pre">logging</span></code>
|
||
package’s namespace, is the list of arguments to the constructor for the handler
|
||
class. Refer to the constructors for the relevant handlers, or to the examples
|
||
below, to see how typical entries are constructed. If not provided, it defaults
|
||
to <code class="docutils literal notranslate"><span class="pre">()</span></code>.</p>
|
||
<p>The optional <code class="docutils literal notranslate"><span class="pre">kwargs</span></code> entry, when <a class="reference internal" href="functions.html#func-eval"><span class="std std-ref">evaluated</span></a> in the context of the
|
||
<code class="docutils literal notranslate"><span class="pre">logging</span></code> package’s namespace, is the keyword argument dict to the constructor
|
||
for the handler class. If not provided, it defaults to <code class="docutils literal notranslate"><span class="pre">{}</span></code>.</p>
|
||
<div class="highlight-ini notranslate"><div class="highlight"><pre><span></span><span class="k">[handler_hand02]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">FileHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">DEBUG</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form02</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">('python.log', 'w')</span>
|
||
|
||
<span class="k">[handler_hand03]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.SocketHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">INFO</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form03</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">('localhost', handlers.DEFAULT_TCP_LOGGING_PORT)</span>
|
||
|
||
<span class="k">[handler_hand04]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.DatagramHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">WARN</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form04</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">('localhost', handlers.DEFAULT_UDP_LOGGING_PORT)</span>
|
||
|
||
<span class="k">[handler_hand05]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.SysLogHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">ERROR</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form05</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">(('localhost', handlers.SYSLOG_UDP_PORT), handlers.SysLogHandler.LOG_USER)</span>
|
||
|
||
<span class="k">[handler_hand06]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.NTEventLogHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">CRITICAL</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form06</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">('Python Application', '', 'Application')</span>
|
||
|
||
<span class="k">[handler_hand07]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.SMTPHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">WARN</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form07</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">('localhost', 'from@abc', ['user1@abc', 'user2@xyz'], 'Logger Subject')</span>
|
||
<span class="na">kwargs</span><span class="o">=</span><span class="s">{'timeout': 10.0}</span>
|
||
|
||
<span class="k">[handler_hand08]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.MemoryHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">NOTSET</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form08</span>
|
||
<span class="na">target</span><span class="o">=</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">(10, ERROR)</span>
|
||
|
||
<span class="k">[handler_hand09]</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">handlers.HTTPHandler</span>
|
||
<span class="na">level</span><span class="o">=</span><span class="s">NOTSET</span>
|
||
<span class="na">formatter</span><span class="o">=</span><span class="s">form09</span>
|
||
<span class="na">args</span><span class="o">=</span><span class="s">('localhost:9022', '/log', 'GET')</span>
|
||
<span class="na">kwargs</span><span class="o">=</span><span class="s">{'secure': True}</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>Sections which specify formatter configuration are typified by the following.</p>
|
||
<div class="highlight-ini notranslate"><div class="highlight"><pre><span></span><span class="k">[formatter_form01]</span>
|
||
<span class="na">format</span><span class="o">=</span><span class="s">F1 %(asctime)s %(levelname)s %(message)s %(customfield)s</span>
|
||
<span class="na">datefmt</span><span class="o">=</span>
|
||
<span class="na">style</span><span class="o">=</span><span class="s">%</span>
|
||
<span class="na">validate</span><span class="o">=</span><span class="s">True</span>
|
||
<span class="na">defaults={'customfield'</span><span class="o">:</span><span class="w"> </span><span class="s">'defaultvalue'</span><span class="na">}</span>
|
||
<span class="na">class</span><span class="o">=</span><span class="s">logging.Formatter</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The arguments for the formatter configuration are the same as the keys
|
||
in the dictionary schema <a class="reference internal" href="#logging-config-dictschema-formatters"><span class="std std-ref">formatters section</span></a>.</p>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">defaults</span></code> entry, when <a class="reference internal" href="functions.html#func-eval"><span class="std std-ref">evaluated</span></a> in the context of
|
||
the <code class="docutils literal notranslate"><span class="pre">logging</span></code> package’s namespace, is a dictionary of default values for
|
||
custom formatting fields. If not provided, it defaults to <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>Due to the use of <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a> as described above, there are
|
||
potential security risks which result from using the <a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a> to send
|
||
and receive configurations via sockets. The risks are limited to where
|
||
multiple users with no mutual trust run code on the same machine; see the
|
||
<a class="reference internal" href="#logging.config.listen" title="logging.config.listen"><code class="xref py py-func docutils literal notranslate"><span class="pre">listen()</span></code></a> documentation for more information.</p>
|
||
</div>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<dl class="simple">
|
||
<dt>Module <a class="reference internal" href="logging.html#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code></a></dt><dd><p>API reference for the logging module.</p>
|
||
</dd>
|
||
<dt>Module <a class="reference internal" href="logging.handlers.html#module-logging.handlers" title="logging.handlers: Handlers for the logging module."><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.handlers</span></code></a></dt><dd><p>Useful handlers included with the logging module.</p>
|
||
</dd>
|
||
</dl>
|
||
</div>
|
||
</section>
|
||
</section>
|
||
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<h3><a href="../contents.html">Table of Contents</a></h3>
|
||
<ul>
|
||
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.config</span></code> — Logging configuration</a><ul>
|
||
<li><a class="reference internal" href="#configuration-functions">Configuration functions</a></li>
|
||
<li><a class="reference internal" href="#security-considerations">Security considerations</a></li>
|
||
<li><a class="reference internal" href="#configuration-dictionary-schema">Configuration dictionary schema</a><ul>
|
||
<li><a class="reference internal" href="#dictionary-schema-details">Dictionary Schema Details</a></li>
|
||
<li><a class="reference internal" href="#incremental-configuration">Incremental Configuration</a></li>
|
||
<li><a class="reference internal" href="#object-connections">Object connections</a></li>
|
||
<li><a class="reference internal" href="#user-defined-objects">User-defined objects</a></li>
|
||
<li><a class="reference internal" href="#handler-configuration-order">Handler configuration order</a></li>
|
||
<li><a class="reference internal" href="#access-to-external-objects">Access to external objects</a></li>
|
||
<li><a class="reference internal" href="#access-to-internal-objects">Access to internal objects</a></li>
|
||
<li><a class="reference internal" href="#import-resolution-and-custom-importers">Import resolution and custom importers</a></li>
|
||
<li><a class="reference internal" href="#configuring-queuehandler-and-queuelistener">Configuring QueueHandler and QueueListener</a></li>
|
||
</ul>
|
||
</li>
|
||
<li><a class="reference internal" href="#configuration-file-format">Configuration file format</a></li>
|
||
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|
||
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|
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<p class="topless"><a href="logging.html"
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title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code> — Logging facility for Python</a></p>
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