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# ================================================================================
# Copyright (c) 2018 AT&T Intellectual Property. 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.
# ============LICENSE_END=========================================================
#
# ECOMP is a trademark and service mark of AT&T Intellectual Property.
"""
policy-receiver communicates with policy-engine
thru web-socket to receive push notifications
on updates and removal of policies.
on receiving the policy-notifications, the policy-receiver
passes the notifications to policy-updater
"""
import json
import logging
import time
from threading import Lock, Thread
import websocket
from .config import Config, Settings
from .policy_consts import MATCHING_CONDITIONS, POLICY_NAME, POLICY_VERSION
from .policy_updater import PolicyUpdater
LOADED_POLICIES = 'loadedPolicies'
REMOVED_POLICIES = 'removedPolicies'
POLICY_VER = 'versionNo'
POLICY_MATCHES = 'matches'
class _PolicyReceiver(Thread):
"""web-socket to PolicyEngine"""
_logger = logging.getLogger("policy_handler.policy_receiver")
def __init__(self):
"""web-socket inside the thread to receive policy notifications from PolicyEngine"""
Thread.__init__(self, name="policy_receiver", daemon=True)
self._lock = Lock()
self._keep_running = True
self._settings = Settings(Config.FIELD_POLICY_ENGINE)
self._web_socket_url = None
self._web_socket = None
self.reconfigure()
self._policy_updater = PolicyUpdater(self.reconfigure)
self._policy_updater.start()
def reconfigure(self):
"""configure and reconfigure the web-socket"""
with self._lock:
self._settings.set_config(Config.discovered_config)
changed, config = self._settings.get_by_key(Config.FIELD_POLICY_ENGINE)
if not changed:
self._settings.commit_change()
return False
prev_web_socket_url = self._web_socket_url
resturl = config.get("url", "") + config.get("path_pdp", "")
if resturl.startswith("https:"):
self._web_socket_url = resturl.replace("https:", "wss:") + "notifications"
else:
self._web_socket_url = resturl.replace("http:", "ws:") + "notifications"
if self._web_socket_url == prev_web_socket_url:
_PolicyReceiver._logger.info("not changed web_socket_url(%s): %s",
self._web_socket_url, self._settings)
self._settings.commit_change()
return False
_PolicyReceiver._logger.info("changed web_socket_url(%s): %s",
self._web_socket_url, self._settings)
self._settings.commit_change()
self._stop_notifications()
return True
def run(self):
"""listen on web-socket and pass the policy notifications to policy-updater"""
websocket.enableTrace(True)
restarting = False
while True:
if not self._get_keep_running():
break
self._stop_notifications()
if restarting:
time.sleep(5)
_PolicyReceiver._logger.info(
"connecting to policy-notifications at: %s", self._web_socket_url)
self._web_socket = websocket.WebSocketApp(
self._web_socket_url,
on_message=self._on_pdp_message,
on_close=self._on_ws_close,
on_error=self._on_ws_error
)
_PolicyReceiver._logger.info("waiting for policy-notifications...")
self._web_socket.run_forever()
restarting = True
_PolicyReceiver._logger.info("exit policy-receiver")
def _get_keep_running(self):
"""thread-safe check whether to continue running"""
with self._lock:
keep_running = self._keep_running
return keep_running
def _stop_notifications(self):
"""close the web-socket == stops the notification service if running."""
with self._lock:
if self._web_socket and self._web_socket.sock and self._web_socket.sock.connected:
self._web_socket.close()
_PolicyReceiver._logger.info("Stopped receiving notifications from PDP")
def _on_pdp_message(self, *args):
"""received the notification from PDP"""
try:
message = args and args[-1]
_PolicyReceiver._logger.info("Received notification message: %s", message)
if not message:
return
message = json.loads(message)
if not message or not isinstance(message, dict):
_PolicyReceiver._logger.warning("unexpected message from PDP: %s",
json.dumps(message))
return
policies_updated = [
{POLICY_NAME: policy.get(POLICY_NAME),
POLICY_VERSION: policy.get(POLICY_VER),
MATCHING_CONDITIONS: policy.get(POLICY_MATCHES, {})}
for policy in message.get(LOADED_POLICIES, [])
]
policies_removed = [
{POLICY_NAME: removed_policy.get(POLICY_NAME),
POLICY_VERSION: removed_policy.get(POLICY_VER)}
for removed_policy in message.get(REMOVED_POLICIES, [])
]
if not policies_updated and not policies_removed:
_PolicyReceiver._logger.info("no policy updated or removed")
return
self._policy_updater.policy_update(policies_updated, policies_removed)
except Exception as ex:
error_msg = "crash {} {} at {}: {}".format(type(ex).__name__, str(ex),
"on_pdp_message", json.dumps(message))
_PolicyReceiver._logger.exception(error_msg)
def _on_ws_error(self, error):
"""report an error"""
_PolicyReceiver._logger.exception("policy-notification error: %s", str(error))
def _on_ws_close(self, code, reason):
"""restart web-socket on close"""
_PolicyReceiver._logger.info("lost connection(%s, %s) to PDP - restarting...", code, reason)
def shutdown(self, audit):
"""Shutdown the policy-receiver"""
_PolicyReceiver._logger.info("shutdown policy-receiver")
with self._lock:
self._keep_running = False
self._stop_notifications()
if self.is_alive():
self.join()
self._policy_updater.shutdown(audit)
def catch_up(self, audit):
"""need to bring the latest policies to DCAE-Controller"""
self._policy_updater.catch_up(audit)
class PolicyReceiver(object):
"""policy-receiver - static singleton wrapper"""
_policy_receiver = None
@staticmethod
def shutdown(audit):
"""Shutdown the notification-handler"""
PolicyReceiver._policy_receiver.shutdown(audit)
@staticmethod
def catch_up(audit):
"""bring the latest policies from policy-engine"""
PolicyReceiver._policy_receiver.catch_up(audit)
@staticmethod
def run(audit):
"""Using policy-engine client to talk to policy engine"""
PolicyReceiver._policy_receiver = _PolicyReceiver()
PolicyReceiver._policy_receiver.start()
PolicyReceiver.catch_up(audit)
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