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pyramid_debugtoolbar

Overview

pyramid_debugtoolbar provides a debug toolbar useful while you’re developing a Pyramid application.

The toolbar is a blatant rip-off of Michael van Tellingen’s flask-debugtoolbar (which itself was derived from Rob Hudson’s django-debugtoolbar). It also includes a lightly sanded down version of the Werkzeug debugger code by Armin Ronacher and team.

Warning

This package only works with Pyramid 1.2a1 and better.

Installation

Install using setuptools, e.g. (within a virtualenv):

$ easy_install pyramid_debugtoolbar

Setup

Once the pyramid_debugtoolbar is installed, you must use the config.include mechanism to include it into your Pyramid project’s configuration:

config = Configurator(.....)
config.include('pyramid_debugtoolbar')

Alternately, you may activate the toolbar by changing your application’s .ini file by adding it to the pyramid.includes list:

pyramid.includes = pyramid_debugtoolbar

Warning

The debug toolbar should never be enabled in a production environment or on a machine with its Pyramid HTTP port exposed directly to the internet; it allows arbitrary code execution from only semi-trusted sources when configured poorly.

Usage

Once Pyramid is restarted, the toolbar will be available to inspect requests and responses by the application by visiting the /_debug_toolbar URL. For example, if your application is available at http://localhost:6543/ then you may visit http://localhost:6543/_debug_toolbar to inspect the requests.

For any HTML responses generated by the application, a link to the toolbar for the current page will be available in the upper right corner, provided the response contains a closing </body> tag.

Debugging Unhandled Exceptions

If an exception is unhandled by the Pyramid application, the toolbar will catch it and render an HTML page with a traceback and an interactive debugger that can be used to dive into the stack and execute arbitrary Python expressions to inspect the state of the system.

A URL leading to a debugging page for each exception raised by your application will additionally be logged to the console.

Settings

Settings can be used to control the operation of the toolbar. These settings are typically specified in the Pyramid “app” section of the Pyramid .ini file.

debugtoolbar.hosts

If the request’s REMOTE_ADDR is not in this list, the toolbar will not be displayed and the exception handler will not be active. Default: [‘127.0.0.1’, ‘::1’]. Note that each of the values in the list can be a hostmask e.g. (192.168.1.0/24).

This should be a list if setup is done in Python or, if defined in a Paste ini file, a single-line list of IP addresses/hostmasks separated by spaces. For example:

debugtoolbar.hosts = 192.168.1.1 192.168.2.0/24

To enable access from any host, use the hostmask 0.0.0.0/0.

debugtoolbar.enabled

true if the toolbar is enabled; false if the toolbar is disabled. Default: true. This disables both the exception handler and the toolbar overlay.

debugtoolbar.intercept_exc

This setting can have one of three values: display, debug or false. Default: debug. If this value is display, the toolbar will display a “pretty” traceback page which allows source viewing and when an exception happens. If this value is debug, the “pretty” traceback page will be shown, but it will also contain interactive debugging controls which allow you to evaluate arbitrary Python expressions in the context of a portion of the traceback, which is useful when attempting to track down the cause of the exception. If this value is false, the “pretty” traceback will be disabled and all exceptions will be raised to the caller of the Pyramid application (usually a WSGI server). Default: debug. This setting differs from debugtoolbar.enabled: it only enables or disables the exception handler. Note that, for backwards compatibility purposes, the value true provided to this setting is interpreted as debug.

debugtoolbar.eval_exc

true if real-time exception debugging is enabled when intercept_exc is true; false if real-time exception debugging is disabled. Default: true. This differs from debugtoolbar.intercept_exc: it only controls whether the pretty exception rendering displays real-time in-browser debugging controls. The real-time in-browser debugging controls allow you to evaluate arbitrary Python expresssions in the context of a stack frame via a browser control.

debugtoolbar.show_on_exc_only

Default: false. If set to true the debugtoolbar will only be injected into the response in case a exception is raised. If the response is processed without exception the returned html code is not changed by the debugtoolbar at all. This option allows the developer to use the toolbar for debugging purposes without interfering with successful responses. E.g. the debugtoolbar button on the right might turn out to be a visual issue if the website uses the same area. And especially in large projects the html code generated by the toolbar slows down the page rendering significantly.

Inspection of requests is still possible by visiting the toolbar manually.

debugtoolbar.intercept_redirects

true if the redirection handler is enabled; false if the handler is disabled. Default: false. This differs from debugtoolbar.enabled: it only enables or disables the redirection handler.

debugtoolbar.panels

A list of dotted Python global names to panel classes. Defaults to a list of all panel types known by pyramid_debugtoolbar, as documented in pyramid_debugtoolbar API. If this is spelled in an .ini file, it should be a space- or newline-separated sequence of dotted Python names. For example:

debugtoolbar.panels =
    pyramid_debugtoolbar.panels.versions.VersionDebugPanel
    pyramid_debugtoolbar.panels.settings.SettingsDebugPanel
    pyramid_debugtoolbar.panels.headers.HeaderDebugPanel
    pyramid_debugtoolbar.panels.request_vars.RequestVarsDebugPanel
    pyramid_debugtoolbar.panels.renderings.RenderingsDebugPanel
    pyramid_debugtoolbar.panels.logger.LoggingPanel
    pyramid_debugtoolbar.panels.performance.PerformanceDebugPanel
    pyramid_debugtoolbar.panels.routes.RoutesDebugPanel
    pyramid_debugtoolbar.panels.sqla.SQLADebugPanel
    pyramid_debugtoolbar.panels.tweens.TweensDebugPanel
    pyramid_debugtoolbar.panels.introspection.IntrospectionDebugPanel

debugtoolbar.button_style

Any inline css styles you want to apply to the toolbar button. This will override the default style (top:30px) set by toolbar.css. If, for example, you want the toolbar button to show up at the bottom off the screen, just set debugtoolbar.button_style to ‘top:auto;bottom:30px;’. If you’re browser support the zoom property, you can even control the magnification level of the toolbar button (ie. ‘zoom:50%’).

debugtoolbar.exclude_prefixes

The debug toolbar won’t be shown if the PATH_INFO variable starts with any of the prefixes listed in this setting. If configuration is done via an .ini file, the prefixes should be separated by carriage returns. For example:

debugtoolbar.exclude_prefixes =
    /manage
    /settings

If configuration is done via Python, the setting should be a list. This setting was added in debugtoolbar version 1.0.4.

Custom authorization

Since version 1.0.5 pyramid_debugtoolbar offers custom authorization mechanism to control toolbar feature on per-request basis. Using config.set_debugtoolbar_request_authorization(callback) directive you can specify own function to control whether toolbar functionality is enabled or not.

Note

Custom authorization is performed after successful IP address check. If debugtoolbar.hosts settings option is used.

Note

Custom authorization does not have effect on pyramid_debugtoolbar static route and /_debug_toolbar/static/* contents will still be accessible.

from pyramid.security import authenticated_userid
from pyramid.settings import aslist

def admin_only_debugtoolbar(request):
    """
    Enable toolbar for administrators only.
    Returns True when it should be enabled.
    """
    admins = aslist(request.registry.settings.get('admins', ''))
    userid = authenticated_userid(request)
    toolbar_enabled = userid and userid in admins
    return toolbar_enabled

config = Configurator(.....)
config.include('pyramid_debugtoolbar')
config.set_debugtoolbar_request_authorization(admin_only_debugtoolbar)

The Toolbar

When you include the toolbar in your application, a floating toolbar logo will appear over your application’s HTML:

_images/toolbar-closed.png

If you click on the “Pyramid DT” logo, a new target window will open with your current request highlighted and all of your configured panels loaded.

_images/toolbar-open.png

Toolbar Panels

These are the default toolbar panels:

Versions

Displays versions of all installed Python software as well as the Python version and platform itself.

_images/versions.png

Settings

Displays Pyramid deployment settings (aka registry.settings).

_images/settings.png

HTTP Headers

Displays HTTP request and response headers for the current page.

_images/headers.png

Request Vars

Displays objects attached to the request of the current page and the WSGI environment.

_images/requestvars.png

Renderings

Displays the renderings performed by Pyramid for the current page.

_images/renderings.png

Logging

Displays messages logged by the current page.

_images/logging.png

Performance

Displays timing information, and, if enabled, Python profiling information for the current page. When it is red, only timing will be done and no profiling information.

Note

An internal profiler can be enabled through the performance checkmark in the Settings tab in the navigation bar. When the checkbox is green, the request will be profiled and profiling information will be gathered and displayed on the Performance panel output.

_images/performance.png

Routes

Displays the routes currently configured in your application.

_images/routes.png

Tweens

Displays the tween chain for your application, and whether they were defined explicitly or implicitly.

_images/tweens.png

SQLAlchemy

Displays SQL queries made by SQLAlchemy by the current page along with timing information.

_images/sqla.png

Provides the ability to re-run the query using the SELECT link.

_images/sqla-select.png

Provides the ability to get more detail about the query using the EXPLAIN link.

_images/sqla-explain.png

Introspection

Displays a rendering of the data available in Pyramid’s configuration introspection system (available in Pyramid 1.3+ only).

_images/introspection.png

Exception Handling

When an exception is raised and the debugtoolbar.intercept_exc setting is display or debug, Pyramid presents a pretty traceback page. If the setting value is debug, you will be able to examine locals in each frame in the traceback and execute code in the context of each frame. Read the instructions on the exception page for more information.

_images/exc.png

Redirect Handling

When a response is returned to Pyramid that has a redirect status code (301, 302, etc) and the debugtoolbar.intercept_redirect setting is true, Pyramid presents an interim page with a link to the target of the redirect. You can use the toolbar on the redirect source page, then when finished, use the link to continue to the target page.

_images/redirect.png

Adding custom panels

In some cases it can be desirable to add a custom panel to the toolbar to display some application specific data. There are two steps for adding such a panel to an application: writing the panel and adding it to your application settings.

Writing the panel

The panel can be created as part of your application or as a standalone package. The easiest way to write a panel is to subclass from the pyramid_debugtoolbar.panels.DebugPanel class. Here is the code for a sample panel:

from pyramid_debugtoolbar.panels import DebugPanel

_ = lambda x: x

class SampleDebugPanel(DebugPanel):
    """
    Sample debug panel
    """
    name = 'Sample'
    has_content = True

    def nav_title(self):
        return _('Sample')

    def url(self):
        return ''

    def title(self):
        return _('Sample')

    def content(self):
        vars = {'somelist':['sample value', 'another value']}
        return self.render(
            'samplepanel:templates/sample.mako',
            vars, self.request)

def includeme(config):
    config.registry.settings['debugtoolbar.panels'].append(SampleDebugPanel)

After inheriting from the DebugPanel class, you have to define a few methods on your panel:

nav_title

Returns a function that can be called to get the title to be used on the toolbar’s navigation bar for this panel.

url

This is not used at the moment, but it has to be provided because the base class will raise NotImplemented if it’s not there.

title

Returns a function that can be called to get the title to be used on the panel’s display page.

content

Returns the panel’s content for display. It can return an HTML response directly, but normally it’s better to use a template, like in the example.

Once you define the panel it has to be added to the debugtoolbar.panels setting of the configuration. A good way to do this is to use an includeme method in the panel’s __init__.py.

Configuring an application to use the panel

Once your panel is ready, you can simply add its package name to the pyramid.includes setting on your application configuration file:

pyramid.includes =
    pyramid_debugtoolbar
    samplepanel

Reporting Bugs / Development Versions

Visit http://github.com/Pylons/pyramid_debugtoolbar to download development or tagged versions.

Visit http://github.com/Pylons/pyramid_debugtoolbar/issues to report bugs.