178 lines
9.9 KiB
HTML
178 lines
9.9 KiB
HTML
|
<!DOCTYPE html>
|
|||
|
|
|
|||
|
|
<html lang="en" data-content_root="./">
|
|||
|
|
<head>
|
|||
|
|
<meta charset="utf-8" />
|
|||
|
|
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
|
|||
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|||
|
|
<title>Debugging Application Errors — Flask Documentation (3.2.x)</title>
|
|||
|
|
<link rel="stylesheet" type="text/css" href="_static/pygments.css?v=6625fa76" />
|
|||
|
|
<link rel="stylesheet" type="text/css" href="_static/flask.css?v=b87c8d14" />
|
|||
|
|
<script src="_static/documentation_options.js?v=56528222"></script>
|
|||
|
|
<script src="_static/doctools.js?v=9bcbadda"></script>
|
|||
|
|
<script src="_static/sphinx_highlight.js?v=dc90522c"></script>
|
|||
|
|
<script data-project="flask" data-version="3.2.x" src="_static/describe_version.js?v=fa7f30d0"></script>
|
|||
|
|
<link rel="icon" href="_static/shortcut-icon.png"/>
|
|||
|
|
<link rel="index" title="Index" href="genindex.html" />
|
|||
|
|
<link rel="search" title="Search" href="search.html" />
|
|||
|
|
<link rel="next" title="Logging" href="logging.html" />
|
|||
|
|
<link rel="prev" title="Handling Application Errors" href="errorhandling.html" />
|
|||
|
|
</head><body>
|
|||
|
|
<div class="related" role="navigation" aria-label="Related">
|
|||
|
|
<h3>Navigation</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li class="right" style="margin-right: 10px">
|
|||
|
|
<a href="genindex.html" title="General Index"
|
|||
|
|
accesskey="I">index</a></li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="py-modindex.html" title="Python Module Index"
|
|||
|
|
>modules</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="logging.html" title="Logging"
|
|||
|
|
accesskey="N">next</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="errorhandling.html" title="Handling Application Errors"
|
|||
|
|
accesskey="P">previous</a> |</li>
|
|||
|
|
<li class="nav-item nav-item-0"><a href="index.html">Flask Documentation (3.2.x)</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-this"><a href="">Debugging Application Errors</a></li>
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<div class="document">
|
|||
|
|
<div class="documentwrapper">
|
|||
|
|
<div class="bodywrapper">
|
|||
|
|
<div class="body" role="main">
|
|||
|
|
|
|||
|
|
<section id="debugging-application-errors">
|
|||
|
|
<h1>Debugging Application Errors<a class="headerlink" href="#debugging-application-errors" title="Link to this heading">¶</a></h1>
|
|||
|
|
<section id="in-production">
|
|||
|
|
<h2>In Production<a class="headerlink" href="#in-production" title="Link to this heading">¶</a></h2>
|
|||
|
|
<p><strong>Do not run the development server, or enable the built-in debugger, in
|
|||
|
|
a production environment.</strong> The debugger allows executing arbitrary
|
|||
|
|
Python code from the browser. It’s protected by a pin, but that should
|
|||
|
|
not be relied on for security.</p>
|
|||
|
|
<p>Use an error logging tool, such as Sentry, as described in
|
|||
|
|
<a class="reference internal" href="errorhandling.html#error-logging-tools"><span class="std std-ref">Error Logging Tools</span></a>, or enable logging and notifications as
|
|||
|
|
described in <a class="reference internal" href="logging.html"><span class="doc">Logging</span></a>.</p>
|
|||
|
|
<p>If you have access to the server, you could add some code to start an
|
|||
|
|
external debugger if <code class="docutils literal notranslate"><span class="pre">request.remote_addr</span></code> matches your IP. Some IDE
|
|||
|
|
debuggers also have a remote mode so breakpoints on the server can be
|
|||
|
|
interacted with locally. Only enable a debugger temporarily.</p>
|
|||
|
|
</section>
|
|||
|
|
<section id="the-built-in-debugger">
|
|||
|
|
<h2>The Built-In Debugger<a class="headerlink" href="#the-built-in-debugger" title="Link to this heading">¶</a></h2>
|
|||
|
|
<p>The built-in Werkzeug development server provides a debugger which shows
|
|||
|
|
an interactive traceback in the browser when an unhandled error occurs
|
|||
|
|
during a request. This debugger should only be used during development.</p>
|
|||
|
|
<img alt="screenshot of debugger in action" class="screenshot align-center" src="_images/debugger.png" />
|
|||
|
|
<div class="admonition warning">
|
|||
|
|
<p class="admonition-title">Warning</p>
|
|||
|
|
<p>The debugger allows executing arbitrary Python code from the
|
|||
|
|
browser. It is protected by a pin, but still represents a major
|
|||
|
|
security risk. Do not run the development server or debugger in a
|
|||
|
|
production environment.</p>
|
|||
|
|
</div>
|
|||
|
|
<p>The debugger is enabled by default when the development server is run in debug mode.</p>
|
|||
|
|
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>$ flask --app hello run --debug
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
<p>When running from Python code, passing <code class="docutils literal notranslate"><span class="pre">debug=True</span></code> enables debug mode, which is
|
|||
|
|
mostly equivalent.</p>
|
|||
|
|
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">app</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="n">debug</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
<p><a class="reference internal" href="server.html"><span class="doc">Development Server</span></a> and <a class="reference internal" href="cli.html"><span class="doc">Command Line Interface</span></a> have more information about running the debugger and
|
|||
|
|
debug mode. More information about the debugger can be found in the <a class="reference external" href="https://werkzeug.palletsprojects.com/debug/">Werkzeug
|
|||
|
|
documentation</a>.</p>
|
|||
|
|
</section>
|
|||
|
|
<section id="external-debuggers">
|
|||
|
|
<h2>External Debuggers<a class="headerlink" href="#external-debuggers" title="Link to this heading">¶</a></h2>
|
|||
|
|
<p>External debuggers, such as those provided by IDEs, can offer a more
|
|||
|
|
powerful debugging experience than the built-in debugger. They can also
|
|||
|
|
be used to step through code during a request before an error is raised,
|
|||
|
|
or if no error is raised. Some even have a remote mode so you can debug
|
|||
|
|
code running on another machine.</p>
|
|||
|
|
<p>When using an external debugger, the app should still be in debug mode, otherwise Flask
|
|||
|
|
turns unhandled errors into generic 500 error pages. However, the built-in debugger and
|
|||
|
|
reloader should be disabled so they don’t interfere with the external debugger.</p>
|
|||
|
|
<div class="highlight-text notranslate"><div class="highlight"><pre><span></span>$ flask --app hello run --debug --no-debugger --no-reload
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
<p>When running from Python:</p>
|
|||
|
|
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">app</span><span class="o">.</span><span class="n">run</span><span class="p">(</span><span class="n">debug</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">use_debugger</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">use_reloader</span><span class="o">=</span><span class="kc">False</span><span class="p">)</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
<p>Disabling these isn’t required, an external debugger will continue to work with the
|
|||
|
|
following caveats.</p>
|
|||
|
|
<ul>
|
|||
|
|
<li><p>If the built-in debugger is not disabled, it will catch unhandled exceptions before
|
|||
|
|
the external debugger can.</p></li>
|
|||
|
|
<li><p>If the reloader is not disabled, it could cause an unexpected reload if code changes
|
|||
|
|
during a breakpoint.</p></li>
|
|||
|
|
<li><p>The development server will still catch unhandled exceptions if the built-in
|
|||
|
|
debugger is disabled, otherwise it would crash on any error. If you want that (and
|
|||
|
|
usually you don’t) pass <code class="docutils literal notranslate"><span class="pre">passthrough_errors=True</span></code> to <code class="docutils literal notranslate"><span class="pre">app.run</span></code>.</p>
|
|||
|
|
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">app</span><span class="o">.</span><span class="n">run</span><span class="p">(</span>
|
|||
|
|
<span class="n">debug</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">passthrough_errors</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span>
|
|||
|
|
<span class="n">use_debugger</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">use_reloader</span><span class="o">=</span><span class="kc">False</span>
|
|||
|
|
<span class="p">)</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
</section>
|
|||
|
|
</section>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="clearer"></div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<span id="sidebar-top"></span>
|
|||
|
|
<div class="sphinxsidebar" role="navigation" aria-label="Main">
|
|||
|
|
<div class="sphinxsidebarwrapper">
|
|||
|
|
|
|||
|
|
|
|||
|
|
<p class="logo"><a href="index.html">
|
|||
|
|
<img class="logo" src="_static/flask-vertical.png" alt="Logo of Flask"/>
|
|||
|
|
</a></p>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<h3>Contents</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li><a class="reference internal" href="#">Debugging Application Errors</a><ul>
|
|||
|
|
<li><a class="reference internal" href="#in-production">In Production</a></li>
|
|||
|
|
<li><a class="reference internal" href="#the-built-in-debugger">The Built-In Debugger</a></li>
|
|||
|
|
<li><a class="reference internal" href="#external-debuggers">External Debuggers</a></li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
<h3>Navigation</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li><a href="index.html">Overview</a>
|
|||
|
|
<ul>
|
|||
|
|
<li>Previous: <a href="errorhandling.html" title="previous chapter">Handling Application Errors</a>
|
|||
|
|
<li>Next: <a href="logging.html" title="next chapter">Logging</a>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
<search id="searchbox" style="display: none" role="search">
|
|||
|
|
<h3 id="searchlabel">Quick search</h3>
|
|||
|
|
<div class="searchformwrapper">
|
|||
|
|
<form class="search" action="search.html" method="get">
|
|||
|
|
<input type="text" name="q" aria-labelledby="searchlabel" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"/>
|
|||
|
|
<input type="submit" value="Go" />
|
|||
|
|
</form>
|
|||
|
|
</div>
|
|||
|
|
</search>
|
|||
|
|
<script>document.getElementById('searchbox').style.display = "block"</script><div id="ethical-ad-placement"></div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="clearer"></div>
|
|||
|
|
</div>
|
|||
|
|
<div class="footer" role="contentinfo">
|
|||
|
|
© Copyright 2010 Pallets.
|
|||
|
|
Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 8.1.3.
|
|||
|
|
</div>
|
|||
|
|
</body>
|
|||
|
|
</html>
|