Launch API in the same process as conductor for singleprocess Ironic

Indirection proved to impose very high performance costs. Even though
we've identified and fixed a few major contributors to the regression,
using RPC for a process to access itself has always been a stopgap
measure rather than a proper architecture.

This change moves the API from a separate service under the Launcher
to a separate thread in the conductor, similarly to how the JSON RPC
server is started. This paves the way to remove the local RPC entirely
in the next patch.

Change-Id: I0f3d854336bcc7ea1062f9a995e6d8979cb0cc22
Signed-off-by: Dmitry Tantsur <dtantsur@protonmail.com>

ironic/command/singleprocess.py

@@ -19,12 +19,9 @@ from oslo_service import service
 from ironic.command import conductor as conductor_cmd
 from ironic.command import utils
 from ironic.common import service as ironic_service
-from ironic.common import wsgi_service
 from ironic.conductor import local_rpc
 from ironic.conductor import rpc_service
 from ironic.console import novncproxy_service
-from ironic.objects import base as objects_base
-from ironic.objects import indirection
 
 CONF = cfg.CONF
 
@@ -53,19 +50,11 @@ def main():
 
     mgr = rpc_service.RPCService(CONF.host,
                                  'ironic.conductor.manager',
-                                 'ConductorManager')
+                                 'ConductorManager',
+                                 embed_api=True)
     conductor_cmd.issue_startup_warnings(CONF)
     launcher.launch_service(mgr)
 
-    # Sets the indirection API to direct API calls for objects across the
-    # RPC layer.
-    if CONF.rpc_transport in ['local', 'none'] or CONF.use_rpc_for_database:
-        objects_base.IronicObject.indirection_api = \
-            indirection.IronicObjectIndirectionAPI()
-
-    wsgi = wsgi_service.WSGIService('ironic_api', CONF.api.enable_ssl_api)
-    launcher.launch_service(wsgi)
-
     # NOTE(TheJulia): By default, vnc is disabled, and depending on that
     # overall process behavior will change. i.e. we're not going to force
     # single process which breaks systemd process launch detection.

ironic/conductor/rpc_service.py

@@ -21,6 +21,7 @@ from oslo_utils import timeutils
 from ironic.common import console_factory
 from ironic.common import rpc
 from ironic.common import rpc_service
+from ironic.common import wsgi_service
 
 LOG = log.getLogger(__name__)
 CONF = cfg.CONF
@@ -43,8 +44,11 @@ DRAIN = multiprocessing.Event()
 
 class RPCService(rpc_service.BaseRPCService):
 
-    def __init__(self, host, manager_module, manager_class):
+    def __init__(self, host, manager_module, manager_class,
+                 embed_api=False):
         super().__init__(host, manager_module, manager_class)
+        self.apiserver = None
+        self._embed_api = embed_api
 
     @property
     def deregister_on_shutdown(self):
@@ -57,6 +61,11 @@ class RPCService(rpc_service.BaseRPCService):
         super()._real_start()
         rpc.set_global_manager(self.manager)
 
+        if self._embed_api:
+            self.apiserver = wsgi_service.WSGIService(
+                'ironic_api', CONF.api.enable_ssl_api)
+            self.apiserver.start()
+
         # Start in a known state of no console containers running.
         # Any enabled console managed by this conductor will be started
         # after this
@@ -67,6 +76,14 @@ class RPCService(rpc_service.BaseRPCService):
         extend_time = initial_time + datetime.timedelta(
             seconds=CONF.hash_ring_reset_interval)
 
+        # Stop serving the embedded API first to avoid any new requests
+        try:
+            if self.apiserver is not None:
+                self.apiserver.stop()
+                self.apiserver.wait()
+        except Exception:
+            LOG.exception('Service error occurred when stopping the API')
+
         try:
             self.manager.del_host(
                 deregister=self.deregister_on_shutdown,