Octavia driver: agent implementation

The driver is loaded, then terminated whenever a request is issued.
This behavior causes termination of the Octavia listener which is
responsible to the processing of the driver status updates and
statistics processing.
The following change implements an agent which will execute the
listener.

Change-Id: I566aaa65df4ba7455577a539aa9eebb6cc36a099
(cherry picked from commit 24e93461d0)

doc/source/devstack.rst

@@ -155,6 +155,9 @@ Add octavia and python-octaviaclient repos as external repositories and configur
     [controller_worker]
     network_driver = allowed_address_pairs_driver
 
+    [driver_agent]
+    enabled_provider_agents=vmwareagent
+
 NSX-T
 -----
 
@@ -279,6 +282,8 @@ Add octavia and python-octaviaclient repos as external repositories and configur
     [controller_worker]
     network_driver = allowed_address_pairs_driver
 
+    [driver_agent]
+    enabled_provider_agents=vmwareagent
 
 NSX-P
 -----
@@ -360,6 +365,9 @@ Add octavia and python-octaviaclient repos as external repositories and configur
     [controller_worker]
     network_driver = allowed_address_pairs_driver
 
+    [driver_agent]
+    enabled_provider_agents=vmwareagent
+
 Trunk Driver
 ~~~~~~~~~~~~
 

setup.cfg

@@ -95,6 +95,8 @@ vmware_nsx.neutron.nsxv3.housekeeper.jobs =
     mismatch_logical_port = vmware_nsx.plugins.nsx_v3.housekeeper.mismatch_logical_port:MismatchLogicalportJob
 octavia.api.drivers =
     vmwareedge = vmware_nsx.services.lbaas.octavia.octavia_driver:NSXOctaviaDriver
+octavia.driver_agent.provider_agents =
+    vmwareagent = vmware_nsx.services.lbaas.octavia.octavia_driver:vmware_nsx_provider_agent
 [build_sphinx]
 source-dir = doc/source
 build-dir = doc/build

vmware_nsx/services/lbaas/octavia/octavia_driver.py

@@ -15,6 +15,7 @@
 
 import copy
 import socket
+import time
 
 from oslo_config import cfg
 from oslo_log import helpers as log_helpers
@@ -75,7 +76,6 @@ class NSXOctaviaDriver(driver_base.ProviderDriver):
     def __init__(self):
         super(NSXOctaviaDriver, self).__init__()
         self._init_rpc_messaging()
-        self._init_rpc_listener()
         self._init_cert_manager()
         self.repositories = repositories.Repositories()
 
@@ -88,20 +88,6 @@ class NSXOctaviaDriver(driver_base.ProviderDriver):
                                   version='1.0')
         self.client = messaging.RPCClient(transport, target)
 
-    @log_helpers.log_method_call
-    def _init_rpc_listener(self):
-        # Initialize RPC listener
-        topic = d_const.DRIVER_TO_OCTAVIA_TOPIC
-        server = socket.gethostname()
-        target = messaging.Target(topic=topic, server=server,
-                                  exchange="common", fanout=False)
-        endpoints = [NSXOctaviaDriverEndpoint()]
-        access_policy = dispatcher.DefaultRPCAccessPolicy
-
-        self.octavia_server = get_rpc_server(target, endpoints,
-                                             access_policy)
-        self.octavia_server.start()
-
     @log_helpers.log_method_call
     def _init_cert_manager(self):
         self.cert_manager = stevedore_driver.DriverManager(
@@ -589,3 +575,22 @@ class NSXOctaviaDriverEndpoint(driver_lib.DriverLibrary):
         except exceptions.UpdateStatisticsError as e:
             LOG.error("Failed to update Octavia listener statistics. "
                       "Stats %s, Error %s", statistics, e.fault_string)
+
+
+@log_helpers.log_method_call
+def vmware_nsx_provider_agent(exit_event):
+    # Initialize RPC listener
+    topic = d_const.DRIVER_TO_OCTAVIA_TOPIC
+    server = socket.gethostname()
+    target = messaging.Target(topic=topic, server=server,
+                              exchange="common", fanout=False)
+    endpoints = [NSXOctaviaDriverEndpoint()]
+    access_policy = dispatcher.DefaultRPCAccessPolicy
+    get_transport()
+    octavia_server = get_rpc_server(target, endpoints, access_policy)
+    octavia_server.start()
+
+    LOG.info('VMware NSX Octavia provider agent has started.')
+    while not exit_event.is_set():
+        time.sleep(1)
+    LOG.info('VMware NSX Octavia provider agent is exiting.')