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Environment Variables and .ini File Settings

Pyramid behavior can be configured through a combination of operating system environment variables and .ini configuration file application section settings. The meaning of the environment variables and the configuration file settings overlap.

Note

Where a configuration file setting exists with the same meaning as an environment variable, and both are present at application startup time, the environment variable setting takes precedence.

The term “configuration file setting name” refers to a key in the .ini configuration for your application. The configuration file setting names documented in this chapter are reserved for Pyramid use. You should not use them to indicate application-specific configuration settings.

Reloading Templates

When this value is true, templates are automatically reloaded whenever they are modified without restarting the application, so you can see changes to templates take effect immediately during development. This flag is meaningful to Chameleon and Mako templates, as well as most third-party template rendering extensions.

Environment Variable Name Config File Setting Name
PYRAMID_RELOAD_TEMPLATES
pyramid.reload_templates
or reload_templates

Reloading Assets

Don’t cache any asset file data when this value is true. See also Overriding Assets.

Environment Variable Name Config File Setting Name
PYRAMID_RELOAD_ASSETS pyramid.reload_assets or reload_assets

Note

For backwards compatibility purposes, aliases can be used for configurating asset reloading: PYRAMID_RELOAD_RESOURCES (envvar) and pyramid.reload_resources (config file).

Debugging Authorization

Print view authorization failure and success information to stderr when this value is true. See also Debugging View Authorization Failures.

Environment Variable Name Config File Setting Name
PYRAMID_DEBUG_AUTHORIZATION pyramid.debug_authorization or debug_authorization

Debugging Not Found Errors

Print view-related NotFound debug messages to stderr when this value is true. See also NotFound Errors.

Environment Variable Name Config File Setting Name
PYRAMID_DEBUG_NOTFOUND pyramid.debug_notfound or debug_notfound

Debugging Route Matching

Print debugging messages related to url dispatch route matching when this value is true. See also Debugging Route Matching.

Environment Variable Name Config File Setting Name
PYRAMID_DEBUG_ROUTEMATCH pyramid.debug_routematch or debug_routematch

Preventing HTTP Caching

Prevent the http_cache view configuration argument from having any effect globally in this process when this value is true. No http caching-related response headers will be set by the Pyramid http_cache view configuration feature when this is true. See also Influencing HTTP Caching.

Environment Variable Name Config File Setting Name
PYRAMID_PREVENT_HTTP_CACHE pyramid.prevent_http_cache or prevent_http_cache

Debugging All

Turns on all debug* settings.

Environment Variable Name Config File Setting Name
PYRAMID_DEBUG_ALL pyramid.debug_all or debug_all

Reloading All

Turns on all reload* settings.

Environment Variable Name Config File Setting Name
PYRAMID_RELOAD_ALL pyramid.reload_all or reload_all

Default Locale Name

The value supplied here is used as the default locale name when a locale negotiator is not registered. See also Localization-Related Deployment Settings.

Environment Variable Name Config File Setting Name
PYRAMID_DEFAULT_LOCALE_NAME pyramid.default_locale_name or default_locale_name

Including Packages

pyramid.includes instructs your application to include other packages. Using the setting is equivalent to using the pyramid.config.Configurator.include() method.

Config File Setting Name
pyramid.includes

The value supplied as pyramid.includes should be a sequence. The sequence can take several different forms.

  1. It can be a string.

    If it is a string, the package names can be separated by spaces:

      package1 package2 package3
    
    The package names can also be separated by carriage returns::
    
       package1
       package2
       package3
  2. It can be a Python list, where the values are strings:

    ['package1', 'package2', 'package3']
    

Each value in the sequence should be a dotted Python name.

pyramid.includes vs. pyramid.config.Configurator.include()

Two methods exist for including packages: pyramid.includes and pyramid.config.Configurator.include(). This section explains their equivalence.

Using PasteDeploy

Using the following pyramid.includes setting in the PasteDeploy .ini file in your application:

[app:main]
pyramid.includes = pyramid_debugtoolbar
                   pyramid_tm

Is equivalent to using the following statements in your configuration code:

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from pyramid.config import Configurator

def main(global_config, **settings):
    config = Configurator(settings=settings)
    # ...
    config.include('pyramid_debugtoolbar')
    config.include('pyramid_tm')
    # ...

It is fine to use both or either form.

Plain Python

Using the following pyramid.includes setting in your plain-Python Pyramid application:

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from pyramid.config import Configurator

if __name__ == '__main__':
    settings = {'pyramid.includes':'pyramid_debugtoolbar pyramid_tm'}
    config = Configurator(settings=settings)

Is equivalent to using the following statements in your configuration code:

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from pyramid.config import Configurator

if __name__ == '__main__':
    settings = {}
    config = Configurator(settings=settings)
    config.include('pyramid_debugtoolbar')
    config.include('pyramid_tm')

It is fine to use both or either form.

Explicit Tween Configuration

This value allows you to perform explicit tween ordering in your configuration. Tweens are bits of code used by add-on authors to extend Pyramid. They form a chain, and require ordering.

Ideally, you won’t need to use the pyramid.tweens setting at all. Tweens are generally ordered and included “implicitly” when an add-on package which registers a tween is “included”. Packages are included when you name a pyramid.includes setting in your configuration or when you call pyramid.config.Configuration.include().

Authors of included add-ons provide “implicit” tween configuration ordering hints to Pyramid when their packages are included. However, the implicit tween ordering is only best-effort. Pyramid will attempt to provide an implicit order of tweens as best it can using hints provided by add-on authors, but because it’s only best-effort, if very precise tween ordering is required, the only surefire way to get it is to use an explicit tween order. You may be required to inspect your tween ordering (see Displaying “Tweens”) and add a pyramid.tweens configuration value at the behest of an add-on author.

Config File Setting Name
pyramid.tweens

The value supplied as pyramid.tweens should be a sequence. The sequence can take several different forms.

  1. It can be a string.

    If it is a string, the tween names can be separated by spaces:

      pkg.tween_factory1 pkg.tween_factory2 pkg.tween_factory3
    
    The tween names can also be separated by carriage returns::
    
       pkg.tween_factory1
       pkg.tween_factory2
       pkg.tween_factory3
  2. It can be a Python list, where the values are strings:

    ['pkg.tween_factory1', 'pkg.tween_factory2', 'pkg.tween_factory3']
    

Each value in the sequence should be a dotted Python name.

PasteDeploy Configuration vs. Plain-Python Configuration

Using the following pyramid.tweens setting in the PasteDeploy .ini file in your application:

[app:main]
pyramid.tweens = pyramid_debugtoolbar.toolbar.tween_factory
                 pyramid.tweens.excview_tween_factory
                 pyramid_tm.tm_tween_factory

Is equivalent to using the following statements in your configuration code:

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from pyramid.config import Configurator

def main(global_config, **settings):
    settings['pyramid.tweens'] = [
            'pyramid_debugtoolbar.toolbar.tween_factory',
            'pyramid.tweebs.excview_tween_factory',
            'pyramid_tm.tm_tween_factory',
             ]
    config = Configurator(settings=settings)

It is fine to use both or either form.

Mako Template Render Settings

Mako derives additional settings to configure its template renderer that should be set when using it. Many of these settings are optional and only need to be set if they should be different from the default. The Mako Template Renderer uses a subclass of Mako’s template lookup and accepts several arguments to configure it.

Mako Directories

The value(s) supplied here are passed in as the template directories. They should be in asset specification format, for example: my.package:templates.

Config File Setting Name
mako.directories

Mako Module Directory

The value supplied here tells Mako where to store compiled Mako templates. If omitted, compiled templates will be stored in memory. This value should be an absolute path, for example: %(here)s/data/templates would use a directory called data/templates in the same parent directory as the INI file.

Config File Setting Name
mako.module_directory

Mako Input Encoding

The encoding that Mako templates are assumed to have. By default this is set to utf-8. If you wish to use a different template encoding, this value should be changed accordingly.

Config File Setting Name
mako.input_encoding

Mako Error Handler

A callable (or a dotted Python name which names a callable) which is called whenever Mako compile or runtime exceptions occur. The callable is passed the current context as well as the exception. If the callable returns True, the exception is considered to be handled, else it is re-raised after the function completes. Is used to provide custom error-rendering functions.

Config File Setting Name
mako.error_handler

Mako Default Filters

List of string filter names that will be applied to all Mako expressions.

Config File Setting Name
mako.default_filters

Mako Import

String list of Python statements, typically individual “import” lines, which will be placed into the module level preamble of all generated Python modules.

Config File Setting Name
mako.imports

Mako Strict Undefined

true or false, representing the “strict undefined” behavior of Mako (see Mako Context Variables). By default, this is false.

Config File Setting Name
mako.strict_undefined

Mako Preprocessor

A callable (or a dotted Python name which names a callable) which is called to preprocess the source before the template is called. The callable will be passed the full template source before it is parsed. The return result of the callable will be used as the template source code.

Note

This feature is new in Pyramid 1.1.

Config File Setting Name
mako.preprocessor

Examples

Let’s presume your configuration file is named MyProject.ini, and there is a section representing your application named [app:main] within the file that represents your Pyramid application. The configuration file settings documented in the above “Config File Setting Name” column would go in the [app:main] section. Here’s an example of such a section:

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[app:main]
use = egg:MyProject
pyramid.reload_templates = true
pyramid.debug_authorization = true

You can also use environment variables to accomplish the same purpose for settings documented as such. For example, you might start your Pyramid application using the following command line:

$ PYRAMID_DEBUG_AUTHORIZATION=1 PYRAMID_RELOAD_TEMPLATES=1 \
       bin/paster serve MyProject.ini

If you started your application this way, your Pyramid application would behave in the same manner as if you had placed the respective settings in the [app:main] section of your application’s .ini file.

If you want to turn all debug settings (every setting that starts with pyramid.debug_). on in one fell swoop, you can use PYRAMID_DEBUG_ALL=1 as an environment variable setting or you may use pyramid.debug_all=true in the config file. Note that this does not affect settings that do not start with pyramid.debug_* such as pyramid.reload_templates.

If you want to turn all pyramid.reload settings (every setting that starts with pyramid.reload_) on in one fell swoop, you can use PYRAMID_RELOAD_ALL=1 as an environment variable setting or you may use pyramid.reload_all=true in the config file. Note that this does not affect settings that do not start with pyramid.reload_* such as pyramid.debug_notfound.

Note

Specifying configuration settings via environment variables is generally most useful during development, where you may wish to augment or override the more permanent settings in the configuration file. This is useful because many of the reload and debug settings may have performance or security (i.e., disclosure) implications that make them undesirable in a production environment.

Understanding the Distinction Between reload_templates and reload_assets

The difference between pyramid.reload_assets and pyramid.reload_templates is a bit subtle. Templates are themselves also treated by Pyramid as asset files (along with other static files), so the distinction can be confusing. It’s helpful to read Overriding Assets for some context about assets in general.

When pyramid.reload_templates is true, Pyramid takes advantage of the underlying templating systems’ ability to check for file modifications to an individual template file. When pyramid.reload_templates is true but pyramid.reload_assets is not true, the template filename returned by the pkg_resources package (used under the hood by asset resolution) is cached by Pyramid on the first request. Subsequent requests for the same template file will return a cached template filename. The underlying templating system checks for modifications to this particular file for every request. Setting pyramid.reload_templates to True doesn’t affect performance dramatically (although it should still not be used in production because it has some effect).

However, when pyramid.reload_assets is true, Pyramid will not cache the template filename, meaning you can see the effect of changing the content of an overridden asset directory for templates without restarting the server after every change. Subsequent requests for the same template file may return different filenames based on the current state of overridden asset directories. Setting pyramid.reload_assets to True affects performance dramatically, slowing things down by an order of magnitude for each template rendering. However, it’s convenient to enable when moving files around in overridden asset directories. pyramid.reload_assets makes the system very slow when templates are in use. Never set pyramid.reload_assets to True on a production system.

Adding A Custom Setting

From time to time, you may need to add a custom setting to your application. Here’s how:

  • If you’re using an .ini file, change the .ini file, adding the setting to the [app:foo] section representing your Pyramid application. For example:

    [app:main]
    # .. other settings
    debug_frobnosticator = True
    
  • In the main() function that represents the place that your Pyramid WSGI application is created, anticipate that you’ll be getting this key/value pair as a setting and do any type conversion necessary.

    If you’ve done any type conversion of your custom value, reset the converted values into the settings dictionary before you pass the dictionary as settings to the Configurator. For example:

    def main(global_config, **settings):
        # ...
        from pyramid.settings import asbool
        debug_frobnosticator = asbool(settings.get(
                   'debug_frobnosticator', 'false'))
        settings['debug_frobnosticator'] = debug_frobnosticator
        config = Configurator(settings=settings)
    

    Note

    It’s especially important that you mutate the settings dictionary with the converted version of the variable before passing it to the Configurator: the configurator makes a copy of settings, it doesn’t use the one you pass directly.

  • When creating an includeme function that will be later added to your application’s configuration you may access the settings dictionary through the instance of the Configurator that is passed into the function as its only argument. For Example:

def includeme(config):
    settings = config.registry.settings
    debug_frobnosticator = settings['debug_frobnosticator']
  • In the runtime code that you need to access the new settings value, find the value in the registry.settings dictionary and use it. In view code (or any other code that has access to the request), the easiest way to do this is via request.registry.settings. For example:

    settings = request.registry.settings
    debug_frobnosticator = settings['debug_frobnosticator']
    

    If you wish to use the value in code that does not have access to the request and you wish to use the value, you’ll need to use the pyramid.threadlocal.get_current_registry() API to obtain the current registry, then ask for its settings attribute. For example:

    registry = pyramid.threadlocal.get_current_registry()
    settings = registry.settings
    debug_frobnosticator = settings['debug_frobnosticator']