ifconfig: T2985: support on demand bridge creation

The current implementation for bridge based interfaces has an issue which is
caused by priority inheritance. We always assumed that the bridge interface will
be created last, but this may not be true in all cases, where some interfaces
will be created "on demand" - e.g. OpenVPN or late (VXLAN, GENEVE).

As we already have a bunch of verify steps in place we should not see a bridge
interface leak to the underlaying infrastructure code. This means, whenever an
interface will be member of a bridge, and the bridge does yet not exist, we will
create it in advance in the interface context, as the bridge code will be run
in the same commit but maybe sooner or later.

This will also be the solution for T2924.

1 files changed, 18 insertions, 10 deletions

diff --git a/python/vyos/ifconfig/bridge.py b/python/vyos/ifconfig/bridge.py
index c133a56fc..7867a7387 100644
--- a/python/vyos/ifconfig/bridge.py
+++ b/python/vyos/ifconfig/bridge.py
@@ -234,25 +234,33 @@ class BridgeIf(Interface):
             if member in interfaces():
                 self.del_port(member)
 
-        STPBridgeIf = STP.enable(BridgeIf)
         tmp = vyos_dict_search('member.interface', config)
         if tmp:
             for interface, interface_config in tmp.items():
-                # if we've come here we already verified the interface
-                # does not have an addresses configured so just flush
-                # any remaining ones
-                Interface(interface).flush_addrs()
+                # if interface does yet not exist bail out early and
+                # add it later
+                if interface not in interfaces():
+                    continue
+
+                # Bridge lower "physical" interface
+                lower = Interface(interface)
+
+                # If we've come that far we already verified the interface does
+                # not have any addresses configured by CLI so just flush any
+                # remaining ones
+                lower.flush_addrs()
                 # enslave interface port to bridge
                 self.add_port(interface)
 
-                tmp = STPBridgeIf(interface)
                 # set bridge port path cost
-                value = interface_config.get('cost')
-                tmp.set_path_cost(value)
+                if 'cost' in interface_config:
+                    value = interface_config.get('cost')
+                    lower.set_path_cost(value)
 
                 # set bridge port path priority
-                value = interface_config.get('priority')
-                tmp.set_path_priority(value)
+                if 'priority' in interface_config:
+                    value = interface_config.get('priority')
+                    lower.set_path_priority(value)
 
         # Enable/Disable of an interface must always be done at the end of the
         # derived class to make use of the ref-counting set_admin_state()