Look for floatingips on configured subnets

Define a new configuration option to list the subnets where
floatingips should be allocated, and use those subnets instead
of all of the subnets on the external network.

Change-Id: Ida1dbd9e463deb36cf3249deaad24e93f49bb575

akanda/neutron/plugins/floatingip.py

@@ -1,7 +1,22 @@
-from neutron.common import exceptions as q_exc
-from neutron.openstack.common import uuidutils
 from neutron.api.v2 import attributes
+from neutron.common import exceptions as q_exc
 from neutron.db.l3_db import DEVICE_OWNER_FLOATINGIP, FloatingIP
+from neutron.openstack.common import uuidutils
+from neutron.openstack.common import log
+
+from oslo.config import cfg
+
+
+LOG = log.getLogger(__name__)
+
+explicit_floating_ip_opts = [
+    cfg.MultiStrOpt(
+        'floatingip_subnet',
+        default=[],
+        help='UUID(s) of subnet(s) from which floating IPs should be allocated',
+        required=True,
+    ),
+]
 
 
 class ExplicitFloatingIPAllocationMixin(object):
@@ -12,7 +27,27 @@ class ExplicitFloatingIPAllocationMixin(object):
 
     """
 
+    def _allocate_floatingip_from_configured_subnets(self, context):
+        cfg.CONF.register_opts(explicit_floating_ip_opts, group='akanda')
+        LOG.debug('looking for floating ip on %s', str(cfg.CONF.akanda.floatingip_subnet))
+        # NOTE(dhellmann): There may be a better way to do this, but
+        # the "filter" argument to get_subnets() is not documented so
+        # who knows.
+        e_context = context.elevated()
+        subnets = [
+            self._get_subnet(e_context, unicode(s))
+            for s in cfg.CONF.akanda.floatingip_subnet
+        ]
+        if not subnets:
+            LOG.error('config setting akanda.floatingip_subnet missing')
+            raise q_exc.IpAddressGenerationFailure(net_id='UNKNOWN')
+        # The base class method _generate_ip() handles the allocation
+        # ranges and going from one subnet to the next when a network
+        # is exhausted.
+        return self._generate_ip(context, subnets)
+
     def create_floatingip(self, context, floatingip):
+        LOG.debug('create_floatingip %s', (floatingip,))
         fip = floatingip['floatingip']
         tenant_id = self._get_tenant_id_for_create(context, fip)
         fip_id = uuidutils.generate_uuid()
@@ -22,6 +57,12 @@ class ExplicitFloatingIPAllocationMixin(object):
             msg = _("Network %s is not a valid external network") % f_net_id
             raise q_exc.BadRequest(resource='floatingip', msg=msg)
 
+        # NOTE(dhellmann): Custom
+        #
+        # FIXME(dhellmann): This should probably verify that the subnet
+        # being used is on the network the user requested.
+        ip_to_use = self._allocate_floatingip_from_configured_subnets(context)
+
         with context.session.begin(subtransactions=True):
             # This external port is never exposed to the tenant.
             # it is used purely for internal system and admin use when
@@ -31,7 +72,8 @@ class ExplicitFloatingIPAllocationMixin(object):
                 {'tenant_id': '',  # tenant intentionally not set
                  'network_id': f_net_id,
                  'mac_address': attributes.ATTR_NOT_SPECIFIED,
-                 'fixed_ips': attributes.ATTR_NOT_SPECIFIED,
+                 # NOTE(dhellmann): Custom
+                 'fixed_ips': [ip_to_use],
                  'admin_state_up': True,
                  'device_id': fip_id,
                  'device_owner': DEVICE_OWNER_FLOATINGIP,