Starting to move to new plugin architecture.

lemur/plugins/base/__init__.py

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+"""
+.. module: lemur.plugins.base
+    :platform: Unix
+    :copyright: (c) 2015 by Netflix Inc., see AUTHORS for more
+    :license: Apache, see LICENSE for more details.
+
+.. moduleauthor:: Kevin Glisson <kglisson@netflix.com>
+"""
+from __future__ import absolute_import, print_function
+
+from lemur.plugins.base.manager import PluginManager
+from lemur.plugins.base.v1 import *  # NOQA
+
+plugins = PluginManager()
+register = plugins.register
+unregister = plugins.unregister

lemur/plugins/base/manager.py

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+"""
+.. module: lemur.plugins.base.manager
+    :copyright: (c) 2015 by Netflix Inc., see AUTHORS for more
+    :license: Apache, see LICENSE for more details.
+
+.. moduleauthor:: Kevin Glisson (kglisson@netflix.com)
+"""
+from flask import current_app
+from lemur.common.managers import InstanceManager
+
+
+# inspired by https://github.com/getsentry/sentry
+class PluginManager(InstanceManager):
+    def __iter__(self):
+        return iter(self.all())
+
+    def __len__(self):
+        return sum(1 for i in self.all())
+
+    def all(self, version=1):
+        for plugin in sorted(super(PluginManager, self).all(), key=lambda x: x.get_title()):
+            if not plugin.is_enabled():
+                continue
+            if version is not None and plugin.__version__ != version:
+                continue
+            yield plugin
+
+    def get(self, slug):
+        for plugin in self.all(version=1):
+            if plugin.slug == slug:
+                return plugin
+        for plugin in self.all(version=2):
+            if plugin.slug == slug:
+                return plugin
+        raise KeyError(slug)
+
+    def first(self, func_name, *args, **kwargs):
+        version = kwargs.pop('version', 1)
+        for plugin in self.all(version=version):
+            try:
+                result = getattr(plugin, func_name)(*args, **kwargs)
+            except Exception as e:
+                current_app.logger.error('Error processing %s() on %r: %s', func_name, plugin.__class__, e, extra={
+                    'func_arg': args,
+                    'func_kwargs': kwargs,
+                }, exc_info=True)
+                continue
+
+            if result is not None:
+                return result
+
+    def register(self, cls):
+        self.add('%s.%s' % (cls.__module__, cls.__name__))
+        return cls
+
+    def unregister(self, cls):
+        self.remove('%s.%s' % (cls.__module__, cls.__name__))
+        return cls
+

lemur/plugins/base/v1.py

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+"""
+.. module: lemur.plugins.base.v1
+    :platform: Unix
+    :copyright: (c) 2015 by Netflix Inc., see AUTHORS for more
+    :license: Apache, see LICENSE for more details.
+
+.. moduleauthor:: Kevin Glisson <kglisson@netflix.com>
+"""
+from threading import local
+
+# stolen from https://github.com/getsentry/sentry/
+class PluginMount(type):
+    def __new__(cls, name, bases, attrs):
+        new_cls = type.__new__(cls, name, bases, attrs)
+        if IPlugin in bases:
+            return new_cls
+        if new_cls.title is None:
+            new_cls.title = new_cls.__name__
+        if not new_cls.slug:
+            new_cls.slug = new_cls.title.replace(' ', '-').lower()
+        return new_cls
+
+
+class IPlugin(local):
+    """
+    Plugin interface. Should not be inherited from directly.
+    A plugin should be treated as if it were a singleton. The owner does not
+    control when or how the plugin gets instantiated, nor is it guaranteed that
+    it will happen, or happen more than once.
+    >>> from lemur.plugins import Plugin
+    >>>
+    >>> class MyPlugin(Plugin):
+    >>>     def get_title(self):
+    >>>         return 'My Plugin'
+    As a general rule all inherited methods should allow ``**kwargs`` to ensure
+    ease of future compatibility.
+    """
+    # Generic plugin information
+    title = None
+    slug = None
+    description = None
+    version = None
+    author = None
+    author_url = None
+    resource_links = ()
+
+    # Configuration specifics
+    conf_key = None
+    conf_title = None
+
+    # Global enabled state
+    enabled = True
+    can_disable = True
+
+    def is_enabled(self, project=None):
+        """
+        Returns a boolean representing if this plugin is enabled.
+        If ``project`` is passed, it will limit the scope to that project.
+        >>> plugin.is_enabled()
+        """
+        if not self.enabled:
+            return False
+        if not self.can_disable:
+            return True
+
+        return True
+
+    def get_conf_key(self):
+        """
+        Returns a string representing the configuration keyspace prefix for this plugin.
+        """
+        if not self.conf_key:
+            self.conf_key = self.get_conf_title().lower().replace(' ', '_')
+        return self.conf_key
+
+    def get_conf_title(self):
+        """
+        Returns a string representing the title to be shown on the configuration page.
+        """
+        return self.conf_title or self.get_title()
+
+    def get_title(self):
+        """
+        Returns the general title for this plugin.
+        >>> plugin.get_title()
+        """
+        return self.title
+
+    def get_description(self):
+        """
+        Returns the description for this plugin. This is shown on the plugin configuration
+        page.
+        >>> plugin.get_description()
+        """
+        return self.description
+
+    def get_resource_links(self):
+        """
+        Returns a list of tuples pointing to various resources for this plugin.
+        >>> def get_resource_links(self):
+        >>>     return [
+        >>>         ('Documentation', 'http://sentry.readthedocs.org'),
+        >>>         ('Bug Tracker', 'https://github.com/getsentry/sentry/issues'),
+        >>>         ('Source', 'https://github.com/getsentry/sentry'),
+        >>>     ]
+        """
+        return self.resource_links
+
+
+class Plugin(IPlugin):
+    """
+    A plugin should be treated as if it were a singleton. The owner does not
+    control when or how the plugin gets instantiated, nor is it guaranteed that
+    it will happen, or happen more than once.
+    """
+    __version__ = 1
+    __metaclass__ = PluginMount