general: import plugin system (#6418)

combo/__init__.py

@@ -0,0 +1,19 @@
+# combo - content management system
+# Copyright (C) 2015  Entr'ouvert
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Affero General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# 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 Affero 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/>.
+
+from . import plugins
+
+plugins.init()

combo/plugins.py

@@ -0,0 +1,75 @@
+# combo - content management system
+# Copyright (C) 2015  Entr'ouvert
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Affero General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# 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 Affero 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/>.
+
+from pkg_resources import iter_entry_points
+import logging
+
+from django.conf.urls import patterns, include, url
+
+logger = logging.getLogger(__name__)
+
+PLUGIN_GROUP_NAME = 'combo.plugin'
+
+class PluginError(Exception):
+    pass
+
+
+def get_plugins(*args, **kwargs):
+    plugins = []
+    for entrypoint in iter_entry_points(PLUGIN_GROUP_NAME):
+        try:
+            plugin = entrypoint.load()
+        except Exception, e:
+            logger.exception('failed to load entrypoint %s', entrypoint)
+            raise PluginError('failed to load entrypoint %s' % entrypoint, e)
+        plugins.append(plugin(*args, **kwargs))
+    return plugins
+
+def register_plugins_urls(urlpatterns):
+    pre_urls = []
+    post_urls = []
+    for plugin in get_plugins():
+        if hasattr(plugin, 'get_before_urls'):
+            pre_urls.append(url('^', include(plugin.get_before_urls())))
+        if hasattr(plugin, 'get_after_urls'):
+            post_urls.append(url('^', include(plugin.get_after_urls())))
+    pre_patterns = patterns('', *pre_urls)
+    post_patterns = patterns('', *post_urls)
+    return pre_patterns + urlpatterns + post_patterns
+
+def register_plugins_apps(installed_apps):
+    for plugin in get_plugins():
+        if hasattr(plugin, 'get_apps'):
+            apps = plugin.get_apps()
+            for app in apps:
+                if app not in installed_apps:
+                    installed_apps += (app, )
+    return installed_apps
+
+def register_plugins_middleware(middlewares):
+    for plugin in get_plugins():
+        if hasattr(plugin, 'get_before_middleware'):
+            pre_middleware = plugin.get_before_middleware()
+            middlewares = tuple(set(pre_middleware + middlewares))
+        if hasattr(plugin, 'get_after_middleware'):
+            post_middleware = plugin.get_after_middleware()
+            middlewares = tuple(set(post_middleware + middlewares))
+    return middlewares
+
+def init():
+    for plugin in get_plugins():
+        if hasattr(plugin, 'init'):
+            plugin.init()

combo/settings.py

@@ -26,6 +26,8 @@ and to disable DEBUG mode in production.
 import os
 from django.conf import global_settings
 
+from . import plugins
+
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
 BASE_DIR = os.path.dirname(os.path.dirname(__file__))
 
@@ -61,6 +63,8 @@ INSTALLED_APPS = (
     'combo.public',
 )
 
+INSTALLED_APPS = plugins.register_plugins_apps(INSTALLED_APPS)
+
 MIDDLEWARE_CLASSES = (
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.common.CommonMiddleware',
@@ -70,6 +74,8 @@ MIDDLEWARE_CLASSES = (
     'django.middleware.clickjacking.XFrameOptionsMiddleware',
 )
 
+MIDDLEWARE_CLASSES = plugins.register_plugins_middleware(MIDDLEWARE_CLASSES)
+
 # Serve xstatic files, required for gadjo
 STATICFILES_FINDERS = global_settings.STATICFILES_FINDERS + \
             ('gadjo.finders.XStaticFinder',)

combo/urls.py

@@ -23,6 +23,8 @@ from .urls_utils import decorated_includes, manager_required
 from .public.views import login, logout
 from .manager.urls import urlpatterns as combo_manager_urls
 
+from . import plugins
+
 urlpatterns = patterns('',
     url(r'^manage/', decorated_includes(manager_required,
         include(combo_manager_urls))),
@@ -41,5 +43,7 @@ urlpatterns += staticfiles_urlpatterns()
 from django.conf.urls.static import static
 urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
 
+urlpatterns = plugins.register_plugins_urls(urlpatterns)
+
 # other URLs are handled as public URLs
 urlpatterns += patterns('', url(r'', include('combo.public.urls')))