heat/heat/service.py

# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2011 Justin Santa Barbara
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""Generic Node base class for all workers that run on hosts."""

import inspect
import os

import eventlet
import logging
import greenlet

from heat.openstack.common import cfg
from heat.openstack.common import importutils

from heat.common import utils as heat_utils
from heat.common import exception
from heat.common import context

from heat import rpc
from heat import version

LOG = logging.getLogger(__name__)


class Launcher(object):
    """
    Launch one or more services and wait for them to complete.
    """

    def __init__(self):
        """Initialize the service launcher.

        :returns: None

        """
        self._services = []

    @staticmethod
    def run_server(server):
        """Start and wait for a server to finish.

        :param service: Server to run and wait for.
        :returns: None

        """
        server.start()
        server.wait()

    def launch_server(self, server):
        """Load and start the given server.

        :param server: The server you would like to start.
        :returns: None

        """
        gt = eventlet.spawn(self.run_server, server)
        self._services.append(gt)

    def stop(self):
        """Stop all services which are currently running.

        :returns: None

        """
        for service in self._services:
            service.kill()

    def wait(self):
        """Waits until all services have been stopped, and then returns.

        :returns: None

        """
        for service in self._services:
            try:
                service.wait()
            except greenlet.GreenletExit:
                pass


class Service(object):
    """Service object for binaries running on hosts.

    A service takes a manager and enables rpc by listening to queues based
    on topic. It also periodically runs tasks on the manager and reports
    it state to the database services table."""

    def __init__(self, host, binary, topic, manager,
                 periodic_interval=None, *args, **kwargs):
        self.host = host
        self.binary = binary
        self.topic = topic
        self.manager_class_name = manager
        manager_class = importutils.import_class(self.manager_class_name)
        self.manager = manager_class(host=self.host, *args, **kwargs)
        self.periodic_interval = periodic_interval
        super(Service, self).__init__(*args, **kwargs)
        self.saved_args, self.saved_kwargs = args, kwargs
        self.timers = []

    def start(self):
        vcs_string = version.version_string_with_vcs()
        LOG.info(_('Starting %(topic)s node (version %(vcs_string)s)'),
                  {'topic': self.topic, 'vcs_string': vcs_string})
        # TODO do we need this ? -> utils.cleanup_file_locks()
        self.manager.init_host()
        self.model_disconnected = False
        ctxt = context.get_admin_context()
        # self._create_service_ref(ctxt)

        self.conn = rpc.create_connection(new=True)
        LOG.debug(_("Creating Consumer connection for Service %s") %
                  self.topic)

        # Share this same connection for these Consumers
        self.conn.create_consumer(self.topic, self, fanout=False)

        node_topic = '%s.%s' % (self.topic, self.host)
        self.conn.create_consumer(node_topic, self, fanout=False)

        self.conn.create_consumer(self.topic, self, fanout=True)

        # Consume from all consumers in a thread
        self.conn.consume_in_thread()

        if self.periodic_interval:
            periodic = heat_utils.LoopingCall(self.periodic_tasks)
            periodic.start(interval=self.periodic_interval, now=False)
            self.timers.append(periodic)

    def __getattr__(self, key):
        manager = self.__dict__.get('manager', None)
        return getattr(manager, key)

    @classmethod
    def create(cls, host=None, binary=None, topic=None, manager=None,
               periodic_interval=None, config=None):
        """Instantiates class and passes back application object.

        :param host: defaults to FLAGS.host
        :param binary: defaults to basename of executable
        :param topic: defaults to bin_name - 'heat-' part
        :param manager: defaults to FLAGS.<topic>_manager
        :param periodic_interval: defaults to FLAGS.periodic_interval

        """
        global FLAGS
        FLAGS = config
        if not host:
            host = FLAGS.host
        if not binary:
            binary = os.path.basename(inspect.stack()[-1][1])
        if not topic:
            topic = binary.rpartition('heat-')[2]
        if not manager:
            manager = FLAGS.get('%s_manager' % topic, None)
        if not periodic_interval:
            periodic_interval = FLAGS.periodic_interval
        service_obj = cls(host, binary, topic, manager,
                          periodic_interval)

        return service_obj

    def kill(self):
        self.stop()

    def stop(self):
        # Try to shut the connection down, but if we get any sort of
        # errors, go ahead and ignore them.. as we're shutting down anyway
        try:
            self.conn.close()
        except Exception:
            pass
        for x in self.timers:
            try:
                x.stop()
            except Exception:
                pass
        self.timers = []

    def wait(self):
        for x in self.timers:
            try:
                x.wait()
            except Exception:
                pass

    def periodic_tasks(self, raise_on_error=False):
        """Tasks to be run at a periodic interval."""
        ctxt = context.get_admin_context()
        self.manager.periodic_tasks(ctxt, raise_on_error=raise_on_error)


# NOTE(vish): the global launcher is to maintain the existing
#             functionality of calling service.serve +
#             service.wait
_launcher = None


def serve(*servers):
    global _launcher
    if not _launcher:
        _launcher = Launcher()
    for server in servers:
        _launcher.launch_server(server)


def wait():
    LOG.debug(_('Full set of FLAGS:'))
    for flag in FLAGS:
        flag_get = FLAGS.get(flag, None)
        # hide flag contents from log if contains a password
        # should use secret flag when switch over to openstack-common
        if ("_password" in flag or "_key" in flag or
                (flag == "sql_connection" and "mysql:" in flag_get)):
            LOG.debug(_('%(flag)s : FLAG SET ') % locals())
        else:
            LOG.debug('%(flag)s : %(flag_get)s' % locals())
    try:
        _launcher.wait()
    except KeyboardInterrupt:
        _launcher.stop()
    rpc.cleanup()