Add flavor/service provider support to routers

This is the initial support for flavors and multiple service
providers with the built-in L3 service plugin.

This patch handles a few key components:

* Adds an optional flavor_id to the router data model
* Adds a new driver controller that performs the following tasks:
  * Loads up the configured drivers and 4 default drivers representing
    the current matrix of ha/dvr options (single node, ha, dvr, and ha+dvr)
  * Associates every router with a driver based on ha/dvr attributes
    or the flavor_id if specified

Note that the current drivers are very limited because they don't do anything.
All of the complex logic for the in-tree drivers is still tied up in the giant
mixin the service plugin inherits. Breaking that apart will be in follow-up
patches.

Partially-Implements: blueprint multi-l3-backends
Change-Id: Idce75bf0fc1375dcbbff9b9803fd2fe97d158cff

neutron/db/l3_db.py

@@ -95,6 +95,8 @@ class Router(model_base.HasStandardAttributes, model_base.BASEV2,
     admin_state_up = sa.Column(sa.Boolean)
     gw_port_id = sa.Column(sa.String(36), sa.ForeignKey('ports.id'))
     gw_port = orm.relationship(models_v2.Port, lazy='joined')
+    flavor_id = sa.Column(sa.String(36),
+                          sa.ForeignKey("flavors.id"), nullable=True)
     attached_ports = orm.relationship(
         RouterPort,
         backref='router',

neutron/db/migration/alembic_migrations/versions/EXPAND_HEAD

@@ -1 +1 @@
-a963b38d82f4
+3d0e74aa7d37

neutron/db/migration/alembic_migrations/versions/newton/expand/3d0e74aa7d37_add_flavor_id_to_routers.py

@@ -0,0 +1,43 @@
+# Copyright 2016 Mirantis
+#
+#    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.
+#
+
+"""Add flavor_id to Router
+
+Revision ID: 3d0e74aa7d37
+Revises: a963b38d82f4
+Create Date: 2016-05-05 00:22:47.618593
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+from neutron.db import migration
+
+
+# revision identifiers, used by Alembic.
+revision = '3d0e74aa7d37'
+down_revision = 'a963b38d82f4'
+
+# milestone identifier, used by neutron-db-manage
+neutron_milestone = [migration.NEWTON]
+
+
+def upgrade():
+    op.add_column('routers',
+                  sa.Column('flavor_id',
+                            sa.String(length=36),
+                            sa.ForeignKey('flavors.id'),
+                            nullable=True))

neutron/extensions/l3_flavors.py

@@ -0,0 +1,55 @@
+#
+# 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.
+#
+
+from neutron_lib import constants
+
+from neutron.api import extensions
+
+EXTENDED_ATTRIBUTES_2_0 = {
+    'routers': {
+        'flavor_id': {'allow_post': True, 'allow_put': False,
+                      'default': constants.ATTR_NOT_SPECIFIED,
+                      'is_visible': True, 'enforce_policy': True}
+
+    }
+}
+
+
+class L3_flavors(extensions.ExtensionDescriptor):
+    """Extension class supporting flavors for routers."""
+
+    @classmethod
+    def get_name(cls):
+        return "Router Flavor Extension"
+
+    @classmethod
+    def get_alias(cls):
+        return 'l3-flavors'
+
+    @classmethod
+    def get_description(cls):
+        return "Flavor support for routers."
+
+    @classmethod
+    def get_updated(cls):
+        return "2016-05-17T00:00:00-00:00"
+
+    def get_extended_resources(self, version):
+        if version == "2.0":
+            return EXTENDED_ATTRIBUTES_2_0
+        else:
+            return {}
+
+    def get_required_extensions(self):
+        return ["router", "flavors"]

neutron/services/l3_router/l3_router_plugin.py

@@ -30,9 +30,11 @@
 from neutron.db import l3_dvrscheduler_db
 from neutron.db import l3_gwmode_db
 from neutron.db import l3_hamode_db
+from neutron.extensions import l3
 from neutron.plugins.common import constants
 from neutron.quota import resource_registry
 from neutron import service
+from neutron.services.l3_router.service_providers import driver_controller
 from neutron.services import service_base
 
 
@@ -55,7 +57,8 @@ class L3RouterPlugin(service_base.ServicePluginBase,
     """
     supported_extension_aliases = ["dvr", "router", "ext-gw-mode",
                                    "extraroute", "l3_agent_scheduler",
-                                   "l3-ha", "router_availability_zone"]
+                                   "l3-ha", "router_availability_zone",
+                                   "l3-flavors"]
 
     __native_pagination_support = True
     __native_sorting_support = True
@@ -76,6 +79,7 @@ def __init__(self):
         rpc_worker = service.RpcWorker([self], worker_process_count=0)
 
         self.add_worker(rpc_worker)
+        self.l3_driver_controller = driver_controller.DriverController(self)
 
     @log_helpers.log_method_call
     def start_rpc_listeners(self):
@@ -111,3 +115,11 @@ def create_floatingip(self, context, floatingip):
         return super(L3RouterPlugin, self).create_floatingip(
             context, floatingip,
             initial_status=n_const.FLOATINGIP_STATUS_DOWN)
+
+
+def add_flavor_id(plugin, router_res, router_db):
+    router_res['flavor_id'] = router_db['flavor_id']
+
+
+common_db_mixin.CommonDbMixin.register_dict_extend_funcs(
+    l3.ROUTERS, [add_flavor_id])

neutron/services/l3_router/service_providers/base.py

@@ -0,0 +1,55 @@
+# 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.
+
+from neutron._i18n import _
+
+
+class _FeatureFlag(object):
+
+    def is_compatible(self, value):
+        if value == self.requires:
+            return True
+        if value and self.supports:
+            return True
+        return False
+
+    def __init__(self, supports, requires):
+        self.supports = supports
+        self.requires = requires
+        if requires and not supports:
+            raise RuntimeError(_("A driver can't require a feature and not "
+                                 "support it."))
+
+UNSUPPORTED = _FeatureFlag(supports=False, requires=False)
+OPTIONAL = _FeatureFlag(supports=True, requires=False)
+MANDATORY = _FeatureFlag(supports=True, requires=True)
+
+
+class L3ServiceProvider(object):
+    """Base class for L3 service providers.
+
+    On __init__ this will be given a handle to the l3 plugin. It is then the
+    responsibility of the driver to subscribe to the events it is interested
+    in (e.g. router_create, router_update, router_delete, etc).
+
+    The 'ha' and 'distributed' attributes below are used to determine if a
+    router request with the 'ha' or 'distributed' attribute can be supported
+    by this particular driver. These attributes must be present.
+    """
+
+    ha_support = UNSUPPORTED
+    distributed_support = UNSUPPORTED
+
+    def __init__(self, l3plugin):
+        self.l3plugin = l3plugin