wsgi-stack: Add a more meaningful comment why we insert the error middleware.

rhodecode/config/middleware.py

@@ -1,463 +1,466 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2010-2016  RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 """
 Pylons middleware initialization
 """
 import logging
 from collections import OrderedDict
 
 from paste.registry import RegistryManager
 from paste.gzipper import make_gzip_middleware
 from pylons.wsgiapp import PylonsApp
 from pyramid.authorization import ACLAuthorizationPolicy
 from pyramid.config import Configurator
 from pyramid.settings import asbool, aslist
 from pyramid.wsgi import wsgiapp
 from pyramid.httpexceptions import (
     HTTPError, HTTPInternalServerError, HTTPFound)
 from pyramid.events import ApplicationCreated
 from pyramid.renderers import render_to_response
 from routes.middleware import RoutesMiddleware
 import routes.util
 
 import rhodecode
 from rhodecode.model import meta
 from rhodecode.config import patches
 from rhodecode.config.routing import STATIC_FILE_PREFIX
 from rhodecode.config.environment import (
     load_environment, load_pyramid_environment)
 from rhodecode.lib.middleware import csrf
 from rhodecode.lib.middleware.appenlight import wrap_in_appenlight_if_enabled
 from rhodecode.lib.middleware.error_handling import (
     PylonsErrorHandlingMiddleware)
 from rhodecode.lib.middleware.https_fixup import HttpsFixup
 from rhodecode.lib.middleware.vcs import VCSMiddleware
 from rhodecode.lib.plugins.utils import register_rhodecode_plugin
 from rhodecode.lib.utils2 import aslist as rhodecode_aslist
 from rhodecode.subscribers import scan_repositories_if_enabled
 
 
 log = logging.getLogger(__name__)
 
 
 # this is used to avoid avoid the route lookup overhead in routesmiddleware
 # for certain routes which won't go to pylons to - eg. static files, debugger
 # it is only needed for the pylons migration and can be removed once complete
 class SkippableRoutesMiddleware(RoutesMiddleware):
     """ Routes middleware that allows you to skip prefixes """
 
     def __init__(self, *args, **kw):
         self.skip_prefixes = kw.pop('skip_prefixes', [])
         super(SkippableRoutesMiddleware, self).__init__(*args, **kw)
 
     def __call__(self, environ, start_response):
         for prefix in self.skip_prefixes:
             if environ['PATH_INFO'].startswith(prefix):
                 # added to avoid the case when a missing /_static route falls
                 # through to pylons and causes an exception as pylons is
                 # expecting wsgiorg.routingargs to be set in the environ
                 # by RoutesMiddleware.
                 if 'wsgiorg.routing_args' not in environ:
                     environ['wsgiorg.routing_args'] = (None, {})
                 return self.app(environ, start_response)
 
         return super(SkippableRoutesMiddleware, self).__call__(
             environ, start_response)
 
 
 def make_app(global_conf, static_files=True, **app_conf):
     """Create a Pylons WSGI application and return it
 
     ``global_conf``
         The inherited configuration for this application. Normally from
         the [DEFAULT] section of the Paste ini file.
 
     ``app_conf``
         The application's local configuration. Normally specified in
         the [app:<name>] section of the Paste ini file (where <name>
         defaults to main).
 
     """
     # Apply compatibility patches
     patches.kombu_1_5_1_python_2_7_11()
     patches.inspect_getargspec()
 
     # Configure the Pylons environment
     config = load_environment(global_conf, app_conf)
 
     # The Pylons WSGI app
     app = PylonsApp(config=config)
     if rhodecode.is_test:
         app = csrf.CSRFDetector(app)
 
     expected_origin = config.get('expected_origin')
     if expected_origin:
         # The API can be accessed from other Origins.
         app = csrf.OriginChecker(app, expected_origin,
                                  skip_urls=[routes.util.url_for('api')])
 
     # Establish the Registry for this application
     app = RegistryManager(app)
 
     app.config = config
 
     return app
 
 
 def make_pyramid_app(global_config, **settings):
     """
     Constructs the WSGI application based on Pyramid and wraps the Pylons based
     application.
 
     Specials:
 
     * We migrate from Pylons to Pyramid. While doing this, we keep both
       frameworks functional. This involves moving some WSGI middlewares around
       and providing access to some data internals, so that the old code is
       still functional.
 
     * The application can also be integrated like a plugin via the call to
       `includeme`. This is accompanied with the other utility functions which
       are called. Changing this should be done with great care to not break
       cases when these fragments are assembled from another place.
 
     """
     # The edition string should be available in pylons too, so we add it here
     # before copying the settings.
     settings.setdefault('rhodecode.edition', 'Community Edition')
 
     # As long as our Pylons application does expect "unprepared" settings, make
     # sure that we keep an unmodified copy. This avoids unintentional change of
     # behavior in the old application.
     settings_pylons = settings.copy()
 
     sanitize_settings_and_apply_defaults(settings)
     config = Configurator(settings=settings)
     add_pylons_compat_data(config.registry, global_config, settings_pylons)
 
     load_pyramid_environment(global_config, settings)
 
     includeme_first(config)
     includeme(config)
     pyramid_app = config.make_wsgi_app()
     pyramid_app = wrap_app_in_wsgi_middlewares(pyramid_app, config)
     pyramid_app.config = config
 
     # creating the app uses a connection - return it after we are done
     meta.Session.remove()
 
     return pyramid_app
 
 
 def make_not_found_view(config):
     """
     This creates the view which should be registered as not-found-view to
     pyramid. Basically it contains of the old pylons app, converted to a view.
     Additionally it is wrapped by some other middlewares.
     """
     settings = config.registry.settings
     vcs_server_enabled = settings['vcs.server.enable']
 
     # Make pylons app from unprepared settings.
     pylons_app = make_app(
         config.registry._pylons_compat_global_config,
         **config.registry._pylons_compat_settings)
     config.registry._pylons_compat_config = pylons_app.config
 
     # Appenlight monitoring.
     pylons_app, appenlight_client = wrap_in_appenlight_if_enabled(
         pylons_app, settings)
 
     # The VCSMiddleware shall operate like a fallback if pyramid doesn't find
     # a view to handle the request. Therefore we wrap it around the pylons app.
     if vcs_server_enabled:
         pylons_app = VCSMiddleware(
             pylons_app, settings, appenlight_client, registry=config.registry)
 
-    # Add an error handling middleware to convert errors from the old pylons
-    # app into a proper error page response.
+    # The pylons app is executed inside of the pyramid 404 exception handler.
+    # Exceptions which are raised inside of it are not handled by pyramid
+    # again. Therefore we add a middleware that invokes the error handler in
+    # case of an exception or error response. This way we return proper error
+    # HTML pages in case of an error.
     reraise = (settings.get('debugtoolbar.enabled', False) or
                rhodecode.disable_error_handler)
     pylons_app = PylonsErrorHandlingMiddleware(
         pylons_app, error_handler, reraise)
 
     # Convert WSGI app to pyramid view and return it.
     return wsgiapp(pylons_app)
 
 
 def add_pylons_compat_data(registry, global_config, settings):
     """
     Attach data to the registry to support the Pylons integration.
     """
     registry._pylons_compat_global_config = global_config
     registry._pylons_compat_settings = settings
 
 
 def error_handler(exception, request):
     from rhodecode.model.settings import SettingsModel
     from rhodecode.lib.utils2 import AttributeDict
 
     try:
         rc_config = SettingsModel().get_all_settings()
     except Exception:
         log.exception('failed to fetch settings')
         rc_config = {}
 
     base_response = HTTPInternalServerError()
     # prefer original exception for the response since it may have headers set
     if isinstance(exception, HTTPError):
         base_response = exception
 
     c = AttributeDict()
     c.error_message = base_response.status
     c.error_explanation = base_response.explanation or str(base_response)
     c.visual = AttributeDict()
 
     c.visual.rhodecode_support_url = (
         request.registry.settings.get('rhodecode_support_url') or
         request.route_url('rhodecode_support')
     )
     c.redirect_time = 0
     c.rhodecode_name = rc_config.get('rhodecode_title', '')
     if not c.rhodecode_name:
         c.rhodecode_name = 'Rhodecode'
 
     c.causes = []
     if hasattr(base_response, 'causes'):
         c.causes = base_response.causes
 
     response = render_to_response(
         '/errors/error_document.html', {'c': c}, request=request,
         response=base_response)
 
     return response
 
 
 def includeme(config):
     settings = config.registry.settings
 
     # plugin information
     config.registry.rhodecode_plugins = OrderedDict()
 
     config.add_directive(
         'register_rhodecode_plugin', register_rhodecode_plugin)
 
     if asbool(settings.get('appenlight', 'false')):
         config.include('appenlight_client.ext.pyramid_tween')
 
     # Includes which are required. The application would fail without them.
     config.include('pyramid_mako')
     config.include('pyramid_beaker')
     config.include('rhodecode.channelstream')
     config.include('rhodecode.admin')
     config.include('rhodecode.authentication')
     config.include('rhodecode.integrations')
     config.include('rhodecode.login')
     config.include('rhodecode.tweens')
     config.include('rhodecode.api')
     config.include('rhodecode.svn_support')
     config.add_route(
         'rhodecode_support', 'https://rhodecode.com/help/', static=True)
 
     # Add subscribers.
     config.add_subscriber(scan_repositories_if_enabled, ApplicationCreated)
 
     # Set the authorization policy.
     authz_policy = ACLAuthorizationPolicy()
     config.set_authorization_policy(authz_policy)
 
     # Set the default renderer for HTML templates to mako.
     config.add_mako_renderer('.html')
 
     # include RhodeCode plugins
     includes = aslist(settings.get('rhodecode.includes', []))
     for inc in includes:
         config.include(inc)
 
     # This is the glue which allows us to migrate in chunks. By registering the
     # pylons based application as the "Not Found" view in Pyramid, we will
     # fallback to the old application each time the new one does not yet know
     # how to handle a request.
     config.add_notfound_view(make_not_found_view(config))
 
     if not settings.get('debugtoolbar.enabled', False):
         # if no toolbar, then any exception gets caught and rendered
         config.add_view(error_handler, context=Exception)
 
     config.add_view(error_handler, context=HTTPError)
 
 
 def includeme_first(config):
     # redirect automatic browser favicon.ico requests to correct place
     def favicon_redirect(context, request):
         return HTTPFound(
             request.static_path('rhodecode:public/images/favicon.ico'))
 
     config.add_view(favicon_redirect, route_name='favicon')
     config.add_route('favicon', '/favicon.ico')
 
     config.add_static_view(
         '_static/deform', 'deform:static')
     config.add_static_view(
         '_static/rhodecode', path='rhodecode:public', cache_max_age=3600 * 24)
 
 
 def wrap_app_in_wsgi_middlewares(pyramid_app, config):
     """
     Apply outer WSGI middlewares around the application.
 
     Part of this has been moved up from the Pylons layer, so that the
     data is also available if old Pylons code is hit through an already ported
     view.
     """
     settings = config.registry.settings
 
     # enable https redirects based on HTTP_X_URL_SCHEME set by proxy
     pyramid_app = HttpsFixup(pyramid_app, settings)
 
     # Add RoutesMiddleware to support the pylons compatibility tween during
     # migration to pyramid.
     pyramid_app = SkippableRoutesMiddleware(
         pyramid_app, config.registry._pylons_compat_config['routes.map'],
         skip_prefixes=(STATIC_FILE_PREFIX, '/_debug_toolbar'))
 
     pyramid_app, _ = wrap_in_appenlight_if_enabled(pyramid_app, settings)
 
     if settings['gzip_responses']:
         pyramid_app = make_gzip_middleware(
             pyramid_app, settings, compress_level=1)
 
 
     # this should be the outer most middleware in the wsgi stack since
     # middleware like Routes make database calls
     def pyramid_app_with_cleanup(environ, start_response):
         try:
             return pyramid_app(environ, start_response)
         finally:
             # Dispose current database session and rollback uncommitted
             # transactions.
             meta.Session.remove()
 
             # In a single threaded mode server, on non sqlite db we should have
             # '0 Current Checked out connections' at the end of a request,
             # if not, then something, somewhere is leaving a connection open
             pool = meta.Base.metadata.bind.engine.pool
             log.debug('sa pool status: %s', pool.status())
 
 
     return pyramid_app_with_cleanup
 
 
 def sanitize_settings_and_apply_defaults(settings):
     """
     Applies settings defaults and does all type conversion.
 
     We would move all settings parsing and preparation into this place, so that
     we have only one place left which deals with this part. The remaining parts
     of the application would start to rely fully on well prepared settings.
 
     This piece would later be split up per topic to avoid a big fat monster
     function.
     """
 
     # Pyramid's mako renderer has to search in the templates folder so that the
     # old templates still work. Ported and new templates are expected to use
     # real asset specifications for the includes.
     mako_directories = settings.setdefault('mako.directories', [
         # Base templates of the original Pylons application
         'rhodecode:templates',
     ])
     log.debug(
         "Using the following Mako template directories: %s",
         mako_directories)
 
     # Default includes, possible to change as a user
     pyramid_includes = settings.setdefault('pyramid.includes', [
         'rhodecode.lib.middleware.request_wrapper',
     ])
     log.debug(
         "Using the following pyramid.includes: %s",
         pyramid_includes)
 
     # TODO: johbo: Re-think this, usually the call to config.include
     # should allow to pass in a prefix.
     settings.setdefault('rhodecode.api.url', '/_admin/api')
 
     # Sanitize generic settings.
     _list_setting(settings, 'default_encoding', 'UTF-8')
     _bool_setting(settings, 'is_test', 'false')
     _bool_setting(settings, 'gzip_responses', 'false')
 
     # Call split out functions that sanitize settings for each topic.
     _sanitize_appenlight_settings(settings)
     _sanitize_vcs_settings(settings)
 
     return settings
 
 
 def _sanitize_appenlight_settings(settings):
     _bool_setting(settings, 'appenlight', 'false')
 
 
 def _sanitize_vcs_settings(settings):
     """
     Applies settings defaults and does type conversion for all VCS related
     settings.
     """
     _string_setting(settings, 'vcs.svn.compatible_version', '')
     _string_setting(settings, 'git_rev_filter', '--all')
     _string_setting(settings, 'vcs.hooks.protocol', 'pyro4')
     _string_setting(settings, 'vcs.server', '')
     _string_setting(settings, 'vcs.server.log_level', 'debug')
     _string_setting(settings, 'vcs.server.protocol', 'pyro4')
     _bool_setting(settings, 'startup.import_repos', 'false')
     _bool_setting(settings, 'vcs.hooks.direct_calls', 'false')
     _bool_setting(settings, 'vcs.server.enable', 'true')
     _bool_setting(settings, 'vcs.start_server', 'false')
     _list_setting(settings, 'vcs.backends', 'hg, git, svn')
     _int_setting(settings, 'vcs.connection_timeout', 3600)
 
 
 def _int_setting(settings, name, default):
     settings[name] = int(settings.get(name, default))
 
 
 def _bool_setting(settings, name, default):
     input = settings.get(name, default)
     if isinstance(input, unicode):
         input = input.encode('utf8')
     settings[name] = asbool(input)
 
 
 def _list_setting(settings, name, default):
     raw_value = settings.get(name, default)
 
     old_separator = ','
     if old_separator in raw_value:
         # If we get a comma separated list, pass it to our own function.
         settings[name] = rhodecode_aslist(raw_value, sep=old_separator)
     else:
         # Otherwise we assume it uses pyramids space/newline separation.
         settings[name] = aslist(raw_value)
 
 
 def _string_setting(settings, name, default):
     settings[name] = settings.get(name, default).lower()