Remove deprecated min_l3_agents_per_router

The option was deprecated [1] for removal in Newton
and is being removed in Ocata.

[1] Deprecated in patch with Gerrit Change-Id of:
    I8a5fc74a96c784d474aefe2d9b27eeb66521ca82

DocImpact remove all references to the option.

Change-Id: I3a9195ff6fd18fad9f85cec03a632e7e52d954e7
Closes-Bug: #1555042

neutron/common/constants.py

@@ -31,8 +31,6 @@ SNAT_ROUTER_INTF_KEY = '_snat_router_interfaces'
 HA_NETWORK_NAME = 'HA network tenant %s'
 HA_SUBNET_NAME = 'HA subnet tenant %s'
 HA_PORT_NAME = 'HA port tenant %s'
-MINIMUM_MINIMUM_AGENTS_FOR_HA = 1
-DEFAULT_MINIMUM_AGENTS_FOR_HA = 2
 HA_ROUTER_STATE_ACTIVE = 'active'
 HA_ROUTER_STATE_STANDBY = 'standby'
 

neutron/db/l3_hamode_db.py

@@ -72,15 +72,6 @@ L3_HA_OPTS = [
                help=_("Maximum number of L3 agents which a HA router will be "
                       "scheduled on. If it is set to 0 then the router will "
                       "be scheduled on every agent.")),
-    cfg.IntOpt('min_l3_agents_per_router',
-               default=n_const.DEFAULT_MINIMUM_AGENTS_FOR_HA,
-               help=_("DEPRECATED: Minimum number of L3 agents that have to "
-                      "be available in order to allow a new HA router to be "
-                      "scheduled. This option is deprecated in the Newton "
-                      "release and will be removed for the Ocata release "
-                      "where the scheduling of new HA routers will always "
-                      "be allowed."),
-               deprecated_for_removal=True),
     cfg.StrOpt('l3_ha_net_cidr',
                default=n_const.L3_HA_NET_CIDR,
                help=_('Subnet used for the l3 HA admin network.')),
@@ -114,15 +105,9 @@ class L3_HA_NAT_db_mixin(l3_dvr_db.L3_NAT_with_dvr_db_mixin,
 
     def _check_num_agents_per_router(self):
         max_agents = cfg.CONF.max_l3_agents_per_router
-        min_agents = cfg.CONF.min_l3_agents_per_router
 
-        if (max_agents != UNLIMITED_AGENTS_PER_ROUTER
+        if max_agents != UNLIMITED_AGENTS_PER_ROUTER and max_agents < 1:
-            and max_agents < min_agents):
+            raise l3_ha.HAMaximumAgentsNumberNotValid(max_agents=max_agents)
-            raise l3_ha.HAMaximumAgentsNumberNotValid(
-                max_agents=max_agents, min_agents=min_agents)
-
-        if min_agents < n_const.MINIMUM_MINIMUM_AGENTS_FOR_HA:
-            raise l3_ha.HAMinimumAgentsNumberNotValid()
 
     def __new__(cls, *args, **kwargs):
         inst = super(L3_HA_NAT_db_mixin, cls).__new__(cls, *args, **kwargs)
@@ -273,14 +258,8 @@ class L3_HA_NAT_db_mixin(l3_dvr_db.L3_NAT_with_dvr_db_mixin,
         return ha_network
 
     def get_number_of_agents_for_scheduling(self, context):
-        """Return the number of agents on which the router will be scheduled.
+        """Return number of agents on which the router will be scheduled."""
 
-        Raises an exception if there are not enough agents available to honor
-        the min_agents config parameter. If the max_agents parameter is set to
-        0 all the agents will be used.
-        """
-
-        min_agents = cfg.CONF.min_l3_agents_per_router
         num_agents = len(self.get_l3_agents(context, active=True,
             filters={'agent_modes': [constants.L3_AGENT_MODE_LEGACY,
                                      constants.L3_AGENT_MODE_DVR_SNAT]}))
@@ -293,10 +272,6 @@ class L3_HA_NAT_db_mixin(l3_dvr_db.L3_NAT_with_dvr_db_mixin,
             else:
                 num_agents = max_agents
 
-        if num_agents < min_agents:
-            raise l3_ha.HANotEnoughAvailableAgents(min_agents=min_agents,
-                                                   num_agents=num_agents)
-
         return num_agents
 
     @db_api.retry_if_session_inactive()
@@ -475,11 +450,6 @@ class L3_HA_NAT_db_mixin(l3_dvr_db.L3_NAT_with_dvr_db_mixin,
                         'set router admin_state_up to False prior to upgrade.')
                 raise n_exc.BadRequest(resource='router', msg=msg)
 
-            if requested_ha_state:
-                # This will throw HANotEnoughAvailableAgents if there aren't
-                # enough l3 agents to handle this router.
-                self.get_number_of_agents_for_scheduling(context)
-
         with context.session.begin(subtransactions=True):
             router_db = super(L3_HA_NAT_db_mixin, self)._update_router_db(
                 context, router_id, data)

neutron/extensions/l3_ext_ha_mode.py

@@ -18,7 +18,6 @@ from neutron_lib import constants
 from neutron_lib import exceptions
 
 from neutron._i18n import _
-from neutron.common import constants as n_const
 
 HA_INFO = 'ha'
 EXTENDED_ATTRIBUTES_2_0 = {
@@ -76,21 +75,10 @@ class HANetworkCIDRNotValid(exceptions.NeutronException):
                 "isn't valid; %(cidr)s.")
 
 
-class HANotEnoughAvailableAgents(exceptions.NeutronException):
-    message = _("Not enough l3 agents available to ensure HA. Minimum "
-                "required %(min_agents)s, available %(num_agents)s.")
-
-
 class HAMaximumAgentsNumberNotValid(exceptions.NeutronException):
     message = _("max_l3_agents_per_router %(max_agents)s config parameter "
-                "is not valid. It has to be greater than or equal to "
+                "is not valid as it cannot be negative. It must be 1 or "
-                "min_l3_agents_per_router %(min_agents)s.")
+                "greater. Alternatively, it can be 0 to mean unlimited.")
-
-
-class HAMinimumAgentsNumberNotValid(exceptions.NeutronException):
-    message = (_("min_l3_agents_per_router config parameter is not valid. "
-                 "It has to be greater than or equal to %s for HA.") %
-               n_const.MINIMUM_MINIMUM_AGENTS_FOR_HA)
 
 
 class L3_ext_ha_mode(extensions.ExtensionDescriptor):

neutron/scheduler/l3_agent_scheduler.py

@@ -26,7 +26,7 @@ from oslo_log import log as logging
 import six
 from sqlalchemy import sql
 
-from neutron._i18n import _LE, _LW
+from neutron._i18n import _LW
 from neutron.common import utils
 from neutron.db import api as db_api
 from neutron.db import l3_hamode_db
@@ -44,7 +44,6 @@ cfg.CONF.register_opts(l3_hamode_db.L3_HA_OPTS)
 class L3Scheduler(object):
 
     def __init__(self):
-        self.min_ha_agents = cfg.CONF.min_l3_agents_per_router
         self.max_ha_agents = cfg.CONF.max_l3_agents_per_router
 
     @abc.abstractmethod
@@ -299,13 +298,6 @@ class L3Scheduler(object):
         return (min(self.max_ha_agents, candidates_count) if self.max_ha_agents
                 else candidates_count)
 
-    def _enough_candidates_for_ha(self, candidates):
-        if not candidates or len(candidates) < self.min_ha_agents:
-            LOG.error(_LE("Not enough candidates, a HA router needs at least "
-                          "%s agents"), self.min_ha_agents)
-            return False
-        return True
-
     def _add_port_from_net_and_ensure_vr_id(self, plugin, ctxt, router_db,
                                             tenant_id, ha_net):
         plugin._ensure_vr_id(ctxt, router_db, ha_net)
@@ -379,9 +371,6 @@ class L3Scheduler(object):
                         tenant_id, candidates):
         """Bind a HA router to agents based on a specific policy."""
 
-        if not self._enough_candidates_for_ha(candidates):
-            return
-
         chosen_agents = self._choose_router_agents_for_ha(
             plugin, context, candidates)
 

neutron/tests/functional/scheduler/test_l3_agent_scheduler.py

@@ -344,10 +344,6 @@ class L3AZLeastRoutersSchedulerTestCase(L3AZSchedulerBaseTest):
             Maximum number of agents on which a router will be scheduled.
             0 means test for regular router.
 
-        min_l3_agents_per_router
-            Minimum number of agents on which a router will be scheduled.
-            N/A for regular router test.
-
         down_agent_count[each az]
             Number of l3 agents which are down.
 
@@ -361,7 +357,6 @@ class L3AZLeastRoutersSchedulerTestCase(L3AZSchedulerBaseTest):
               router_az_hints=1,
               agent_count=[1, 1],
               max_l3_agents_per_router=0,
-              min_l3_agents_per_router=0,
               down_agent_count=[0, 0],
               expected_scheduled_agent_count=[1, 0])),
 
@@ -370,7 +365,6 @@ class L3AZLeastRoutersSchedulerTestCase(L3AZSchedulerBaseTest):
               router_az_hints=2,
               agent_count=[1, 1, 1],
               max_l3_agents_per_router=2,
-              min_l3_agents_per_router=2,
               down_agent_count=[0, 0, 0],
               expected_scheduled_agent_count=[1, 1, 0])),
 
@@ -379,18 +373,8 @@ class L3AZLeastRoutersSchedulerTestCase(L3AZSchedulerBaseTest):
               router_az_hints=2,
               agent_count=[2, 1],
               max_l3_agents_per_router=3,
-              min_l3_agents_per_router=2,
               down_agent_count=[0, 0],
               expected_scheduled_agent_count=[2, 1])),
-
-        ('HA router, not enough agents',
-         dict(az_count=3,
-              router_az_hints=2,
-              agent_count=[2, 2, 2],
-              max_l3_agents_per_router=3,
-              min_l3_agents_per_router=2,
-              down_agent_count=[1, 1, 0],
-              expected_scheduled_agent_count=[1, 1, 0])),
     ]
 
     def setUp(self):
@@ -402,7 +386,6 @@ class L3AZLeastRoutersSchedulerTestCase(L3AZSchedulerBaseTest):
         ha = False
         if self.max_l3_agents_per_router:
             self.config(max_l3_agents_per_router=self.max_l3_agents_per_router)
-            self.config(min_l3_agents_per_router=self.min_l3_agents_per_router)
             ha = True
 
         # create l3 agents
@@ -451,10 +434,6 @@ class L3AZAutoScheduleTestCaseBase(L3AZSchedulerBaseTest):
             Maximum number of agents on which a router will be scheduled.
             0 means test for regular router.
 
-        min_l3_agents_per_router
-            Minimum number of agents on which a router will be scheduled.
-            N/A for regular router test.
-
         down_agent_count[each az]
             Number of l3 agents which are down.
 
@@ -472,7 +451,6 @@ class L3AZAutoScheduleTestCaseBase(L3AZSchedulerBaseTest):
               agent_az='az0',
               agent_count=[1, 1],
               max_l3_agents_per_router=0,
-              min_l3_agents_per_router=0,
               down_agent_count=[1, 1],
               scheduled_agent_count=[0, 0],
               expected_scheduled_agent_count=[1, 0])),
@@ -483,7 +461,6 @@ class L3AZAutoScheduleTestCaseBase(L3AZSchedulerBaseTest):
               agent_az='az1',
               agent_count=[1, 1],
               max_l3_agents_per_router=0,
-              min_l3_agents_per_router=0,
               down_agent_count=[1, 1],
               scheduled_agent_count=[0, 0],
               expected_scheduled_agent_count=[0, 0])),
@@ -494,7 +471,6 @@ class L3AZAutoScheduleTestCaseBase(L3AZSchedulerBaseTest):
               agent_az='az1',
               agent_count=[1, 1, 1],
               max_l3_agents_per_router=2,
-              min_l3_agents_per_router=2,
               down_agent_count=[0, 1, 0],
               scheduled_agent_count=[0, 0, 0],
               expected_scheduled_agent_count=[0, 1, 0])),
@@ -505,7 +481,6 @@ class L3AZAutoScheduleTestCaseBase(L3AZSchedulerBaseTest):
               agent_az='az2',
               agent_count=[1, 1, 1],
               max_l3_agents_per_router=2,
-              min_l3_agents_per_router=2,
               down_agent_count=[0, 0, 1],
               scheduled_agent_count=[0, 0, 0],
               expected_scheduled_agent_count=[0, 0, 0])),
@@ -517,7 +492,6 @@ class L3AZAutoScheduleTestCaseBase(L3AZSchedulerBaseTest):
         ha = False
         if self.max_l3_agents_per_router:
             self.config(max_l3_agents_per_router=self.max_l3_agents_per_router)
-            self.config(min_l3_agents_per_router=self.min_l3_agents_per_router)
             ha = True
 
         # create l3 agents

neutron/tests/unit/db/test_l3_hamode_db.py

@@ -119,19 +119,8 @@ class L3HATestCase(L3HATestFramework):
             l3_ext_ha_mode.HANetworkCIDRNotValid,
             self.plugin._verify_configuration)
 
-    def test_verify_configuration_min_l3_agents_per_router_below_minimum(self):
+    def test_verify_configuration_max_l3_agents_below_0(self):
-        cfg.CONF.set_override('min_l3_agents_per_router', 0)
+        cfg.CONF.set_override('max_l3_agents_per_router', -5)
-        self.assertRaises(
-            l3_ext_ha_mode.HAMinimumAgentsNumberNotValid,
-            self.plugin._check_num_agents_per_router)
-
-    def test_verify_configuration_min_l3_agents_per_router_eq_one(self):
-        cfg.CONF.set_override('min_l3_agents_per_router', 1)
-        self.plugin._check_num_agents_per_router()
-
-    def test_verify_configuration_max_l3_agents_below_min_l3_agents(self):
-        cfg.CONF.set_override('max_l3_agents_per_router', 3)
-        cfg.CONF.set_override('min_l3_agents_per_router', 4)
         self.assertRaises(
             l3_ext_ha_mode.HAMaximumAgentsNumberNotValid,
             self.plugin._check_num_agents_per_router)
@@ -323,15 +312,6 @@ class L3HATestCase(L3HATestFramework):
                           ha=True,
                           distributed=True)
 
-    def test_migrate_legacy_router_to_ha_not_enough_agents(self):
-        router = self._create_router(ha=False, distributed=False)
-        self.assertFalse(router['ha'])
-        self.assertFalse(router['distributed'])
-
-        helpers.set_agent_admin_state(self.agent2['id'], admin_state_up=False)
-        self.assertRaises(l3_ext_ha_mode.HANotEnoughAvailableAgents,
-                          self._migrate_router, router['id'], ha=True)
-
     def test_unbind_ha_router(self):
         router = self._create_router()
 
@@ -802,13 +782,6 @@ class L3HATestCase(L3HATestFramework):
             self.admin_ctx)
         self.assertEqual(3, num_ha_candidates)
 
-    def test_get_number_of_agents_for_scheduling_not_enough_agents(self):
-        cfg.CONF.set_override('min_l3_agents_per_router', 3)
-        helpers.kill_agent(helpers.register_l3_agent(host='l3host_3')['id'])
-        self.assertRaises(l3_ext_ha_mode.HANotEnoughAvailableAgents,
-                          self.plugin.get_number_of_agents_for_scheduling,
-                          self.admin_ctx)
-
     def test_ha_network_deleted_if_no_ha_router_present_two_tenants(self):
         # Create two routers in different tenants.
         router1 = self._create_router()

neutron/tests/unit/scheduler/test_l3_agent_scheduler.py

@@ -39,7 +39,6 @@ from neutron.db.models import agent as agent_model
 from neutron.db.models import l3agent as rb_model
 from neutron.db.models import l3ha as l3ha_model
 from neutron.extensions import l3
-from neutron.extensions import l3_ext_ha_mode as l3_ha
 from neutron.extensions import l3agentscheduler as l3agent
 from neutron.extensions import portbindings
 from neutron import manager
@@ -1555,7 +1554,6 @@ class VacantBindingIndexTestCase(L3HATestCaseMixin):
     def test_get_vacant_binding_index(self):
         helpers.register_l3_agent('host_3')
         cfg.CONF.set_override('max_l3_agents_per_router', 3)
-        cfg.CONF.set_override('min_l3_agents_per_router', 3)
         router = self._create_ha_router()
 
         if self.binding_index:
@@ -1875,18 +1873,6 @@ class L3HAChanceSchedulerTestCase(L3HATestCaseMixin):
                                           'host_3',
                                           routers_to_auto_schedule)
 
-    def test_scheduler_with_ha_enabled_not_enough_agent(self):
-        r1 = self._create_ha_router()
-        agents = self.plugin.get_l3_agents_hosting_routers(
-            self.adminContext, [r1['id']],
-            admin_state_up=True)
-        self.assertEqual(2, len(agents))
-
-        self._set_l3_agent_admin_state(self.adminContext,
-                                       self.agent_id2, False)
-        self.assertRaises(
-            l3_ha.HANotEnoughAvailableAgents, self._create_ha_router)
-
 
 class L3HALeastRoutersSchedulerTestCase(L3HATestCaseMixin):
 

releasenotes/notes/remove-min-l3-agents-per-router-27aef7d91dec0348.yaml

@@ -0,0 +1,12 @@
+---
+upgrade:
+  - The neutron.conf:min_l3_agents_per_router option was
+    deprecated in Newton and removed in Ocata. HA routers
+    no longer require a minimal number of L3 agents to
+    be created, although obviously require at least
+    two L3 agents to provide HA. The rationale for the
+    removal of the option is the case a router was created
+    just when an agent was not operational. The creation
+    of the router will now succeed and when a second agent
+    resumes operation the router will be scheduled to it
+    providing HA.