[eventlet-removal][OVN] Require wsgi start-time in the config

Currently there is one single method to run the Neutron API that is
using uWSGI. This method requires a specific hash ring manager
initialization, different to the eventlet server based.

Because the second has been removed and is no longer available, as
long as Neutron continues the effors of removing eventlet from the
source code, the second way to initialize the hash ring manager
is removed.

Related-Bug: #2083570
Change-Id: I59b25093df9cf5aa77767492a5b9008bfa11cc07

doc/source/eventlet_deprecation/index.rst

@@ -69,7 +69,16 @@ Neutron API
 
 The Neutron API currently can be executed only with the uWSGI module; the
 eventlet executor has been deprecated, although the code has not been removed
-from the repository yet.
+from the repository yet. It is now mandatory to define the configuration
+variable ``start-time`` in the uWSGI configuration file, using the magic
+variable [1]_ "%t" that provides the *unix time (in seconds, gathered at
+instance startup)*.
+
+.. code::
+
+  [uwsgi]
+  start-time = %t
+
 
 The Neutron API consists of the following executables:
 
@@ -89,3 +98,11 @@ The Neutron API consists of the following executables:
 .. note::
 
   Right now, only the API server is running without eventlet.
+
+
+
+
+References
+----------
+
+.. [1] https://uwsgi-docs.readthedocs.io/en/latest/Configuration.html#magic-variables

neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py

@@ -124,10 +124,6 @@ class OVNMechanismDriver(api.MechanismDriver):
         self._maintenance_thread = None
         self._hash_ring_thread = None
         self._hash_ring_probe_event = multiprocessing.Event()
-        self._start_time = wsgi_utils.get_start_time()
-        if self._start_time:
-            LOG.info('Server start time: %s',
-                     str(n_utils.ts_to_datetime(self._start_time)))
         self.node_uuid = None
         self.hash_ring_group = ovn_const.HASH_RING_ML2_GROUP
         self.sg_enabled = ovn_acl.is_sg_enabled()
@@ -148,6 +144,7 @@ class OVNMechanismDriver(api.MechanismDriver):
         self.qos_driver = qos_driver.OVNQosDriver.create(self)
         self.trunk_driver = trunk_driver.OVNTrunkDriver.create(self)
         self.log_driver = log_driver.register(self)
+        self._start_time = None
 
     @property
     def nb_schema_helper(self):
@@ -188,6 +185,24 @@ class OVNMechanismDriver(api.MechanismDriver):
     def sb_ovn(self, val):
         self._sb_ovn = val
 
+    @property
+    def start_time(self):
+        if self._start_time:
+            return self._start_time
+
+        self._start_time = wsgi_utils.get_start_time()
+        if not self._start_time:
+            LOG.warning('uWSGI must provide a start time using the '
+                        'configuration parameter "start-time %t" in the '
+                        'configuration file')
+            # NOTE(ralonsoh): this is happening if the uWSGI configuration file
+            # does not have the "start-time %t" parameter or when using the
+            # Neutron API eventlet server, still in use in the grenade
+            # skip-level jobs. This should be removed in the F release.
+            self._start_time = wsgi_utils.get_start_time(current_time=True)
+
+        return self._start_time
+
     def get_supported_vif_types(self):
         vif_types = set()
         for ch in self.sb_ovn.chassis_list().execute(check_error=True):
@@ -325,12 +340,7 @@ class OVNMechanismDriver(api.MechanismDriver):
         sh = oslo_service.SignalHandler()
         atexit.register(self._remove_node_from_hash_ring)
         sh.add_handler("SIGTERM", self._remove_node_from_hash_ring)
-
-        admin_context = n_context.get_admin_context()
-        if self._start_time:
-            self._setup_hash_ring_start_time(admin_context)
-        else:
-            self._setup_hash_ring_event(admin_context)
+        self._init_hash_ring(n_context.get_admin_context())
         self._register_hash_ring_maintenance()
 
     def _register_hash_ring_maintenance(self):
@@ -346,24 +356,12 @@ class OVNMechanismDriver(api.MechanismDriver):
         LOG.info('Hash Ring probing thread for node %s has started',
                  self.node_uuid)
 
-    def _setup_hash_ring_event(self, context):
-        LOG.debug('Hash Ring setup using multiprocess event lock')
-        if not self._hash_ring_probe_event.is_set():
-            # Clear existing entries. This code section should be executed
-            # only once per node (chassis); the multiprocess event should be
-            # set just after the ``is_set`` check.
-            self._hash_ring_probe_event.set()
-            ovn_hash_ring_db.remove_nodes_from_host(context,
-                                                    self.hash_ring_group)
-        self.node_uuid = ovn_hash_ring_db.add_node(context,
-                                                   self.hash_ring_group)
-
     @db_api.retry_if_session_inactive()
     @db_api.CONTEXT_WRITER
-    def _setup_hash_ring_start_time(self, context):
-        LOG.debug('Hash Ring setup using WSGI start time')
-        # Delete all node registers without created_at=self._start_time
-        created_at = n_utils.ts_to_datetime(self._start_time)
+    def _init_hash_ring(self, context):
+        LOG.debug('Hash Ring setup using WSGI start time %s',
+                  str(n_utils.ts_to_datetime(self.start_time)))
+        created_at = n_utils.ts_to_datetime(self.start_time)
         ovn_hash_ring_db.remove_nodes_from_host(
             context, self.hash_ring_group, created_at=created_at)
         self.node_uuid = ovn_hash_ring_db.add_node(

neutron/tests/functional/plugins/ml2/drivers/ovn/mech_driver/test_mech_driver.py

@@ -62,7 +62,7 @@ VHOSTUSER_VIF_DETAILS = {
 
 class TestOVNMechanismDriver(base.TestOVNFunctionalBase):
 
-    def test__setup_hash_ring_start_time(self):
+    def test__init_hash_ring(self):
         # Create a differentiated OVN hash ring name.
         ring_group = uuidutils.generate_uuid()
         self.mech_driver.hash_ring_group = ring_group
@@ -81,7 +81,7 @@ class TestOVNMechanismDriver(base.TestOVNFunctionalBase):
         start_time = timeutils.utcnow()
         self.mech_driver._start_time = int(start_time.timestamp())
         for _ in range(3):
-            self.mech_driver._setup_hash_ring_start_time(self.context)
+            self.mech_driver._init_hash_ring(self.context)
 
         ovn_hrs = ovn_hash_ring_db.get_nodes(self.context, ring_group)
         self.assertEqual(3, len(ovn_hrs))

releasenotes/notes/add-7c25db94790c671c.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Now it is mandatory to define the ``start-time=%t`` variable in the uWSGI
+    configuration file. It will provide the unix time in seconds, gathered at
+    instance startup. This value is the same for all workers and is persistent
+    if the uWSGI process restarts any of them.