# cherrypy._cpconfig module

Configuration system for CherryPy.

Configuration in CherryPy is implemented via dictionaries. Keys are strings which name the mapped value, which may be of any type.

## Architecture

CherryPy Requests are part of an Application, which runs in a global context, and configuration data may apply to any of those three scopes:

Global

  Configuration entries which apply everywhere are stored in cherrypy.config.

Application

  Entries which apply to each mounted application are stored on the Application object itself, as ‘app.config’. This is a two-level dict where each key is a path, or “relative URL” (for example, “/” or “/path/to/my/page”), and each value is a config dict. Usually, this data is provided in the call to tree.mount(root(), config=conf), although you may also use app.merge(conf).

Request

  Each Request object possesses a single ‘Request.config’ dict. Early in the request process, this dict is populated by merging global config entries, Application entries (whose path equals or is a parent of Request.path_info), and any config acquired while looking up the page handler (see next).

## Declaration

Configuration data may be supplied as a Python dictionary, as a filename, or as an open file object. When you supply a filename or file, CherryPy uses Python’s builtin ConfigParser; you declare Application config by writing each path as a section header:

    [/path/to/my/page]
    request.stream = True

To declare global configuration entries, place them in a [global] section.

You may also declare config entries directly on the classes and methods (page handlers) that make up your CherryPy application via the `_cp_config` attribute, set with the `cherrypy.config` decorator. For example:

    @cherrypy.config(**{'tools.gzip.on': True})
    class Demo:

        @cherrypy.expose
        @cherrypy.config(**{'request.show_tracebacks': False})
        def index(self):
            return "Hello world"

Note

This behavior is only guaranteed for the default dispatcher. Other dispatchers may have different restrictions on where you can attach config attributes.

## Namespaces

Configuration keys are separated into namespaces by the first “.” in the key. Current namespaces:

engine

  Controls the ‘application engine’, including autoreload. These can only be declared in the global config.

tree

  Grafts cherrypy.Application objects onto cherrypy.tree. These can only be declared in the global config.

hooks

  Declares additional request-processing functions.

log

  Configures the logging for each application. These can only be declared in the global or / config.

request

  Adds attributes to each Request.

response

  Adds attributes to each Response.

server

  Controls the default HTTP server via cherrypy.server. These can only be declared in the global config.

tools

  Runs and configures additional request-processing packages.

wsgi

  Adds WSGI middleware to an Application’s “pipeline”. These can only be declared in the app’s root config (“/”).

checker

  Controls the ‘checker’, which looks for common errors in app state (including config) when the engine starts. Global config only.

The only key that does not exist in a namespace is the “environment” entry. This special entry ‘imports’ other config entries from a template stored in cherrypy._cpconfig.environments[environment]. It only applies to the global config, and only when you use cherrypy.config.update.

You can define your own namespaces to be called at the Global, Application, or Request level, by adding a named handler to cherrypy.config.namespaces, app.namespaces, or app.request_class.namespaces. The name can be any string, and the handler must be either a callable or a (Python 2.5 style) context manager.

class cherrypy._cpconfig.Config(file=None, **kwargs)

  Bases: `Config`

  The ‘global’ configuration data for the entire CherryPy process.

  _apply(config)

    Update self from a dict.

  environments = {'embedded': {'checker.on': False, 'engine.SIGHUP': None, 'engine.SIGTERM': None, 'engine.autoreload.on': False, 'log.screen': False, 'request.show_mismatched_params': False, 'request.show_tracebacks': False, 'tools.log_headers.on': False}, 'production': {'checker.on': False, 'engine.autoreload.on': False, 'log.screen': False, 'request.show_mismatched_params': False, 'request.show_tracebacks': False, 'tools.log_headers.on': False}, 'staging': {'checker.on': False, 'engine.autoreload.on': False, 'request.show_mismatched_params': False, 'request.show_tracebacks': False, 'tools.log_headers.on': False}, 'test_suite': {'checker.on': False, 'engine.autoreload.on': False, 'log.screen': False, 'request.show_mismatched_params': True, 'request.show_tracebacks': True, 'tools.log_headers.on': False}}
  update(config)

    Update self from a dict, file or filename.

class cherrypy._cpconfig._Vars(target)

  Bases: `object`

  Adapter allowing setting a default attribute on a function or class.

  setdefault(key, default)

cherrypy._cpconfig._engine_namespace_handler(k, v)

  Config handler for the “engine” namespace.

cherrypy._cpconfig._if_filename_register_autoreload(ob)

  Register for autoreload if ob is a string (presumed filename).

cherrypy._cpconfig._server_namespace_handler(k, v)

  Config handler for the “server” namespace.

cherrypy._cpconfig._tree_namespace_handler(k, v)

  Namespace handler for the ‘tree’ config namespace.

cherrypy._cpconfig.merge(base, other)

  Merge one app config (from a dict, file, or filename) into another.

  If the given config is a filename, it will be appended to the list of files to monitor for “autoreload” changes.