Added plugins module in host plugin

import imp

import logging

from collections import defaultdict

from cloudcontrol.common.client.tags import Tag

from cloudcontrol.common.jobs import Job

from cloudcontrol.common.tql.db.helpers import taggify

logger = logging.getLogger(__name__)

def _tag_direct_use_error(*args, **kwargs):

    raise RuntimeError('Plugins tags can\'t be called directly')

class Plugin(object):

    """ Represent a loaded cloudcontrol plugin.

    """

    def __init__(self, logger, tag_db, name, sha1, plugin_body):

        self.logger = logger

        self.name = name

        self.sha1 = sha1

        self.tag_db = tag_db

        self.methods = {}

        self.events = defaultdict(lambda: [])

        self._load_module(plugin_body)

        self.trigger('install', self)

    def _load_module(self, plugin_body):

        # load the code into a module:

        module = imp.new_module(self.name)

        module.logger = self.logger

        module.tag = self._decorator_tag

        module.method = self._decorator_method

        module.on = self._decorator_event

        try:

            exec plugin_body in module.__dict__

        except Exception:

            err_msg = 'Error during plugin installation (%s)' % self.name

            logger.exception(err_msg)

            raise RuntimeError(err_msg)

        else:

            # prevents module from being garbage collected

            self.module = module

    def _decorator_tag(self, ttl=-1, refresh=None, name=None):

        def decorator(func):

            tag = Tag(func.__name__ if name is None else name,

                      lambda: taggify(func()), ttl=ttl, refresh=refresh)

            self.tag_db.add_tag(tag)

            return _tag_direct_use_error

        return decorator

    def _decorator_method(self, name=None):

        def decorator(func):

            self.methods[func.__name__ if name is None else name] = func

            return func

        return decorator

    def _decorator_event(self, event):

        def decorator(func):

            self.events[event].append(func)

            return func

        return decorator

    def trigger(self, event, *args, **kwargs):

        """Trigger an event."""

        for func in self.events[event]:

            func(*args, **kwargs)

    def uninstall(self):

        self.trigger('uninstall')

        # shutdown the tags database:

        self.tag_db.set_parent(None)

class PluginMethodJob(Job):

    """Job that run a plugin method."""

    def job(self, plugin_name, method_name, method, method_kwargs):

        kwargs_str = ', '.join(('%s=%s' % (k, v) for k, v in method_kwargs.iteritems()))

        self.title = 'Plugin: %s.%s(%s)' % (plugin_name, method_name, kwargs_str)

        try:

            returned = method(self, **method_kwargs)

        except Exception:

            self.logger.exception('Error while executing method')

            raise

        if returned is not None:

            self.attachment('output').write(returned)