401. Plugin infrastructure

* implements installing, loading and setup for plugins
* codifies configuration
* has a sample plugin
* docs
* tests

mediagoblin/init/plugins/__init__.py

@@ -0,0 +1,59 @@
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
+#
+# 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/>.
+
+import logging
+
+from mediagoblin import mg_globals
+from mediagoblin.tools import pluginapi
+
+
+_log = logging.getLogger(__name__)
+
+
+def setup_plugins():
+    """This loads, configures and registers plugins
+
+    See plugin documentation for more details.
+    """
+
+    global_config = mg_globals.global_config
+    plugin_section = global_config.get('plugins', {})
+
+    if not plugin_section:
+        _log.info("No plugins to load")
+        return
+
+    pcache = pluginapi.PluginCache()
+
+    # Go through and import all the modules that are subsections of
+    # the [plugins] section.
+    for plugin_module, config in plugin_section.items():
+        _log.info("Importing plugin module: %s" % plugin_module)
+        # If this throws errors, that's ok--it'll halt mediagoblin
+        # startup.
+        __import__(plugin_module)
+
+    # Note: One side-effect of importing things is that anything that
+    # subclassed pluginapi.Plugin is registered.
+
+    # Go through all the plugin classes, instantiate them, and call
+    # setup_plugin so they can figure things out.
+    for plugin_class in pcache.plugin_classes:
+        name = plugin_class.__module__ + "." + plugin_class.__name__
+        _log.info("Loading plugin: %s" % name)
+        plugin_obj = plugin_class()
+        plugin_obj.setup_plugin()
+        pcache.register_plugin_object(plugin_obj)