Configure access to physical network also with ML2/OVN backend

Neutron L3 module in Devstack has way to conigure access to physical
network on the node. It can put physical interface to the physical
bridge or, in case when such physical device isn't set, it creates
NAT rule in iptables.

There was missing the same operation for ML2/OVN backend as L3 agent is
not used there at all.

This patch adds the same to be done in both L3 agent and ovn_agent
modules.

Closes-Bug: #1939627
Change-Id: I9e558d1d5d3edbce9e7a025ba3c11267f1579820

Author: slawqo

lib/neutron-legacy

@@ -663,6 +663,27 @@ function _move_neutron_addresses_route {
     fi
 }
 
+# _configure_public_network_connectivity() - Configures connectivity to the
+# external network using $PUBLIC_INTERFACE or NAT on the single interface
+# machines
+function _configure_public_network_connectivity {
+    # If we've given a PUBLIC_INTERFACE to take over, then we assume
+    # that we can own the whole thing, and privot it into the OVS
+    # bridge. If we are not, we're probably on a single interface
+    # machine, and we just setup NAT so that fixed guests can get out.
+    if [[ -n "$PUBLIC_INTERFACE" ]]; then
+        _move_neutron_addresses_route "$PUBLIC_INTERFACE" "$OVS_PHYSICAL_BRIDGE" True False "inet"
+
+        if [[ $(ip -f inet6 a s dev "$PUBLIC_INTERFACE" | grep -c 'global') != 0 ]]; then
+            _move_neutron_addresses_route "$PUBLIC_INTERFACE" "$OVS_PHYSICAL_BRIDGE" False False "inet6"
+        fi
+    else
+        for d in $default_v4_route_devs; do
+            sudo iptables -t nat -A POSTROUTING -o $d -s $FLOATING_RANGE -j MASQUERADE
+        done
+    fi
+}
+
 # cleanup_mutnauq() - Remove residual data files, anything left over from previous
 # runs that a clean run would need to clean up
 function cleanup_mutnauq {

lib/neutron_plugins/ovn_agent

@@ -266,6 +266,7 @@ function create_public_bridge {
     # Create the public bridge that OVN will use
     sudo ovs-vsctl --may-exist add-br $PUBLIC_BRIDGE -- set bridge $PUBLIC_BRIDGE protocols=OpenFlow13,OpenFlow15
     sudo ovs-vsctl set open . external-ids:ovn-bridge-mappings=$PHYSICAL_NETWORK:$PUBLIC_BRIDGE
+    _configure_public_network_connectivity
 }
 
 function _disable_libvirt_apparmor {

lib/neutron_plugins/services/l3

@@ -123,21 +123,7 @@ function _configure_neutron_l3_agent {
 
     neutron_plugin_configure_l3_agent $Q_L3_CONF_FILE
 
-    # If we've given a PUBLIC_INTERFACE to take over, then we assume
-    # that we can own the whole thing, and privot it into the OVS
-    # bridge. If we are not, we're probably on a single interface
-    # machine, and we just setup NAT so that fixed guests can get out.
-    if [[ -n "$PUBLIC_INTERFACE" ]]; then
-        _move_neutron_addresses_route "$PUBLIC_INTERFACE" "$OVS_PHYSICAL_BRIDGE" True False "inet"
-
-        if [[ $(ip -f inet6 a s dev "$PUBLIC_INTERFACE" | grep -c 'global') != 0 ]]; then
-            _move_neutron_addresses_route "$PUBLIC_INTERFACE" "$OVS_PHYSICAL_BRIDGE" False False "inet6"
-        fi
-    else
-        for d in $default_v4_route_devs; do
-            sudo iptables -t nat -A POSTROUTING -o $d -s $FLOATING_RANGE -j MASQUERADE
-        done
-    fi
+    _configure_public_network_connectivity
 }
 
 # Explicitly set router id in l3 agent configuration