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# Copyright 2014 Canonical Ltd. This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).
"""RPC implementation for clusters."""
from __future__ import (
absolute_import,
print_function,
unicode_literals,
)
str = None
__metaclass__ = type
__all__ = [
"ClusterClientService",
"ClusterService",
]
from itertools import starmap
import json
from operator import itemgetter
import random
from urlparse import urlparse
from apiclient.utils import ascii_url
from provisioningserver.cluster_config import get_maas_url
from provisioningserver.config import Config
from provisioningserver.pxe import tftppath
from provisioningserver.rpc import cluster
from twisted.application.internet import (
StreamServerEndpointService,
TimerService,
)
from twisted.internet.address import HostnameAddress
from twisted.internet.endpoints import (
connectProtocol,
TCP4ClientEndpoint,
TCP4ServerEndpoint,
)
from twisted.internet.protocol import Factory
from twisted.protocols import amp
from twisted.python import log
from twisted.web.client import getPage
class Cluster(amp.AMP, object):
"""The RPC protocol supported by a cluster controller.
This can be used on the client or server end of a connection; once a
connection is established, AMP is symmetric.
"""
@cluster.ListBootImages.responder
def list_boot_images(self):
images = tftppath.list_boot_images(
Config.load_from_cache()['tftp']['root'])
return {"images": images}
class ClusterService(StreamServerEndpointService):
"""A cluster controller RPC service.
This is a service - in the Twisted sense - that exposes the
``Cluster`` protocol on the given port.
"""
def __init__(self, reactor, port):
super(ClusterService, self).__init__(
TCP4ServerEndpoint(reactor, port),
Factory.forProtocol(Cluster))
class ClusterClient(Cluster):
"""The RPC protocol supported by a cluster controller, client version.
This works hand-in-hand with ``ClusterClientService``, maintaining
the latter's `connections` map.
:ivar address: The :class:`HostnameAddress` of the remote endpoint.
:ivar service: A reference to the :class:`ClusterClientService` that
made self.
"""
address = None
service = None
def connectionMade(self):
super(ClusterClient, self).connectionMade()
if not self.service.running:
self.transport.loseConnection()
elif self.address in self.service.connections:
self.transport.loseConnection()
else:
self.service.connections[self.address] = self
def connectionLost(self, reason):
if self.address in self.service.connections:
if self.service.connections[self.address] is self:
del self.service.connections[self.address]
super(ClusterClient, self).connectionLost(reason)
class ClusterClientService(TimerService, object):
"""A cluster controller RPC client service.
This is a service - in the Twisted sense - that connects to a set of
remote AMP endpoints. The endpoints are obtained from a view in the
region controller and periodically refreshed; this list is used to
update the connections maintained in this service.
:ivar connections: A mapping of endpoints to protocol instances
connected to it.
"""
def __init__(self, reactor):
super(ClusterClientService, self).__init__(
self._get_random_interval(), self.update)
self.connections = {}
self.clock = reactor
def update(self):
"""Refresh outgoing connections.
This obtains a list of endpoints from the region then connects
to new ones and drops connections to those no longer used.
"""
# 0. Update interval.
self._update_interval()
# 1. Obtain RPC endpoints.
d = getPage(self._get_rpc_info_url())
d.addCallback(json.loads)
d.addCallback(itemgetter("endpoints"))
# 2. Open connections to new endpoints.
# 3. Close connections to defunct endpoints.
d.addCallback(self._update_connections)
# 4. Log errors.
d.addErrback(log.err)
return d
@staticmethod
def _get_rpc_info_url():
"""Return the URL to the RPC infomation page on the region."""
url = urlparse(get_maas_url())
url = url._replace(path="%s/rpc" % url.path.rstrip("/"))
url = url.geturl()
return ascii_url(url)
@staticmethod
def _get_random_interval():
"""Return a random interval between 30 and 90 seconds."""
return random.randint(30, 90)
def _update_interval(self):
"""Change the interval randomly to avoid stampedes of clusters."""
self._loop.interval = self.step = self._get_random_interval()
def _update_connections(self, hostports):
connections_established = set(self.connections)
connections_desired = set(starmap(HostnameAddress, hostports))
self._make_connections(connections_desired - connections_established)
self._drop_connections(connections_established - connections_desired)
def _make_connections(self, addresses):
for address in addresses:
endpoint = TCP4ClientEndpoint(
self.clock, address.hostname, address.port)
protocol = ClusterClient()
protocol.address = address
protocol.service = self
connectProtocol(endpoint, protocol)
def _drop_connections(self, addresses):
for address in addresses:
self.connections[address].loseConnection()
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