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290 lines
12 KiB
Plaintext
Error reporting
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===============
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When you're running a public site you should always turn off the
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:setting:`DEBUG` setting. That will make your server run much faster, and will
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also prevent malicious users from seeing details of your application that can be
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revealed by the error pages.
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However, running with :setting:`DEBUG` set to ``False`` means you'll never see
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errors generated by your site -- everyone will just see your public error pages.
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You need to keep track of errors that occur in deployed sites, so Django can be
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configured to create reports with details about those errors.
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Email reports
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-------------
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Server errors
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~~~~~~~~~~~~~
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When :setting:`DEBUG` is ``False``, Django will email the users listed in the
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:setting:`ADMINS` setting whenever your code raises an unhandled exception and
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results in an internal server error (HTTP status code 500). This gives the
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administrators immediate notification of any errors. The :setting:`ADMINS` will
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get a description of the error, a complete Python traceback, and details about
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the HTTP request that caused the error.
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.. note::
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In order to send email, Django requires a few settings telling it
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how to connect to your mail server. At the very least, you'll need
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to specify :setting:`EMAIL_HOST` and possibly
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:setting:`EMAIL_HOST_USER` and :setting:`EMAIL_HOST_PASSWORD`,
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though other settings may be also required depending on your mail
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server's configuration. Consult :doc:`the Django settings
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documentation </ref/settings>` for a full list of email-related
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settings.
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By default, Django will send email from root@localhost. However, some mail
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providers reject all email from this address. To use a different sender
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address, modify the :setting:`SERVER_EMAIL` setting.
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To activate this behavior, put the email addresses of the recipients in the
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:setting:`ADMINS` setting.
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.. seealso::
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Server error emails are sent using the logging framework, so you can
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customize this behavior by :doc:`customizing your logging configuration
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</topics/logging>`.
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404 errors
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~~~~~~~~~~
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Django can also be configured to email errors about broken links (404 "page
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not found" errors). Django sends emails about 404 errors when:
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* :setting:`DEBUG` is ``False``;
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* Your :setting:`MIDDLEWARE_CLASSES` setting includes
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:class:`django.middleware.common.BrokenLinkEmailsMiddleware`.
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If those conditions are met, Django will email the users listed in the
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:setting:`MANAGERS` setting whenever your code raises a 404 and the request has
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a referer. (It doesn't bother to email for 404s that don't have a referer --
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those are usually just people typing in broken URLs or broken Web 'bots).
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.. note::
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:class:`~django.middleware.common.BrokenLinkEmailsMiddleware` must appear
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before other middleware that intercepts 404 errors, such as
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:class:`~django.middleware.locale.LocaleMiddleware` or
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:class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware`.
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Put it towards the top of your :setting:`MIDDLEWARE_CLASSES` setting.
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You can tell Django to stop reporting particular 404s by tweaking the
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:setting:`IGNORABLE_404_URLS` setting. It should be a tuple of compiled
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regular expression objects. For example::
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import re
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IGNORABLE_404_URLS = (
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re.compile(r'\.(php|cgi)$'),
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re.compile(r'^/phpmyadmin/'),
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)
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In this example, a 404 to any URL ending with ``.php`` or ``.cgi`` will *not* be
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reported. Neither will any URL starting with ``/phpmyadmin/``.
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The following example shows how to exclude some conventional URLs that browsers and
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crawlers often request::
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import re
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IGNORABLE_404_URLS = (
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re.compile(r'^/apple-touch-icon.*\.png$'),
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re.compile(r'^/favicon\.ico$'),
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re.compile(r'^/robots\.txt$'),
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)
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(Note that these are regular expressions, so we put a backslash in front of
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periods to escape them.)
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If you'd like to customize the behavior of
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:class:`django.middleware.common.BrokenLinkEmailsMiddleware` further (for
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example to ignore requests coming from web crawlers), you should subclass it
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and override its methods.
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.. seealso::
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404 errors are logged using the logging framework. By default, these log
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records are ignored, but you can use them for error reporting by writing a
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handler and :doc:`configuring logging </topics/logging>` appropriately.
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.. _filtering-error-reports:
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Filtering error reports
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-----------------------
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.. warning::
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Filtering sensitive data is a hard problem, and it's nearly impossible to
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guarantee that sensitive won't leak into an error report. Therefore, error
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reports should only be available to trusted team members and you should
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avoid transmitting error reports unencrypted over the Internet (such as
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through email).
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Filtering sensitive information
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. currentmodule:: django.views.decorators.debug
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Error reports are really helpful for debugging errors, so it is generally
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useful to record as much relevant information about those errors as possible.
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For example, by default Django records the `full traceback`_ for the
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exception raised, each `traceback frame`_’s local variables, and the
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:class:`~django.http.HttpRequest`’s :ref:`attributes<httprequest-attributes>`.
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However, sometimes certain types of information may be too sensitive and thus
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may not be appropriate to be kept track of, for example a user's password or
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credit card number. So Django offers a set of function decorators to help you
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control which information should be filtered out of error reports in a
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production environment (that is, where :setting:`DEBUG` is set to ``False``):
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:func:`sensitive_variables` and :func:`sensitive_post_parameters`.
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.. _`full traceback`: http://en.wikipedia.org/wiki/Stack_trace
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.. _`traceback frame`: http://en.wikipedia.org/wiki/Stack_frame
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.. function:: sensitive_variables(*variables)
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If a function (either a view or any regular callback) in your code uses
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local variables susceptible to contain sensitive information, you may
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prevent the values of those variables from being included in error reports
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using the ``sensitive_variables`` decorator::
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from django.views.decorators.debug import sensitive_variables
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@sensitive_variables('user', 'pw', 'cc')
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def process_info(user):
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pw = user.pass_word
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cc = user.credit_card_number
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name = user.name
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...
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In the above example, the values for the ``user``, ``pw`` and ``cc``
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variables will be hidden and replaced with stars (`**********`) in the
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error reports, whereas the value of the ``name`` variable will be
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disclosed.
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To systematically hide all local variables of a function from error logs,
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do not provide any argument to the ``sensitive_variables`` decorator::
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@sensitive_variables()
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def my_function():
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...
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.. admonition:: When using multiple decorators
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If the variable you want to hide is also a function argument (e.g.
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'``user``’ in the following example), and if the decorated function has
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multiple decorators, then make sure to place ``@sensitive_variables``
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at the top of the decorator chain. This way it will also hide the
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function argument as it gets passed through the other decorators::
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@sensitive_variables('user', 'pw', 'cc')
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@some_decorator
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@another_decorator
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def process_info(user):
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...
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.. function:: sensitive_post_parameters(*parameters)
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If one of your views receives an :class:`~django.http.HttpRequest` object
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with :attr:`POST parameters<django.http.HttpRequest.POST>` susceptible to
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contain sensitive information, you may prevent the values of those
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parameters from being included in the error reports using the
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``sensitive_post_parameters`` decorator::
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from django.views.decorators.debug import sensitive_post_parameters
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@sensitive_post_parameters('pass_word', 'credit_card_number')
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def record_user_profile(request):
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UserProfile.create(user=request.user,
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password=request.POST['pass_word'],
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credit_card=request.POST['credit_card_number'],
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name=request.POST['name'])
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...
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In the above example, the values for the ``pass_word`` and
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``credit_card_number`` POST parameters will be hidden and replaced with
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stars (`**********`) in the request's representation inside the error
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reports, whereas the value of the ``name`` parameter will be disclosed.
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To systematically hide all POST parameters of a request in error reports,
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do not provide any argument to the ``sensitive_post_parameters`` decorator::
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@sensitive_post_parameters()
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def my_view(request):
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...
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All POST parameters are systematically filtered out of error reports for
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certain :mod:`django.contrib.auth.views` views (``login``,
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``password_reset_confirm``, ``password_change``, and ``add_view`` and
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``user_change_password`` in the ``auth`` admin) to prevent the leaking of
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sensitive information such as user passwords.
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.. _custom-error-reports:
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Custom error reports
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~~~~~~~~~~~~~~~~~~~~
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All :func:`sensitive_variables` and :func:`sensitive_post_parameters` do is,
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respectively, annotate the decorated function with the names of sensitive
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variables and annotate the ``HttpRequest`` object with the names of sensitive
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POST parameters, so that this sensitive information can later be filtered out
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of reports when an error occurs. The actual filtering is done by Django's
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default error reporter filter:
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:class:`django.views.debug.SafeExceptionReporterFilter`. This filter uses the
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decorators' annotations to replace the corresponding values with stars
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(`**********`) when the error reports are produced. If you wish to override or
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customize this default behavior for your entire site, you need to define your
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own filter class and tell Django to use it via the
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:setting:`DEFAULT_EXCEPTION_REPORTER_FILTER` setting::
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DEFAULT_EXCEPTION_REPORTER_FILTER = 'path.to.your.CustomExceptionReporterFilter'
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You may also control in a more granular way which filter to use within any
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given view by setting the ``HttpRequest``’s ``exception_reporter_filter``
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attribute::
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def my_view(request):
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if request.user.is_authenticated():
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request.exception_reporter_filter = CustomExceptionReporterFilter()
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...
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.. currentmodule:: django.views.debug
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Your custom filter class needs to inherit from
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:class:`django.views.debug.SafeExceptionReporterFilter` and may override the
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following methods:
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.. class:: SafeExceptionReporterFilter
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.. method:: SafeExceptionReporterFilter.is_active(request)
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Returns ``True`` to activate the filtering operated in the other methods.
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By default the filter is active if :setting:`DEBUG` is ``False``.
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.. method:: SafeExceptionReporterFilter.get_request_repr(request)
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Returns the representation string of the request object, that is, the
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value that would be returned by ``repr(request)``, except it uses the
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filtered dictionary of POST parameters as determined by
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:meth:`SafeExceptionReporterFilter.get_post_parameters`.
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.. method:: SafeExceptionReporterFilter.get_post_parameters(request)
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Returns the filtered dictionary of POST parameters. By default it replaces
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the values of sensitive parameters with stars (`**********`).
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.. method:: SafeExceptionReporterFilter.get_traceback_frame_variables(request, tb_frame)
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Returns the filtered dictionary of local variables for the given traceback
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frame. By default it replaces the values of sensitive variables with stars
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(`**********`).
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.. seealso::
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You can also set up custom error reporting by writing a custom piece of
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:ref:`exception middleware <exception-middleware>`. If you do write custom
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error handling, it's a good idea to emulate Django's built-in error handling
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and only report/log errors if :setting:`DEBUG` is ``False``.
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