ifconfig: T2653: implement update() in derived classes for admin up/down

Every derived class must implement update() to set the interfaces admin
up/down state. This is required to prevend extensive link flaps when e.g.
reconfiguring bond interfaces.

1 files changed, 11 insertions, 1 deletions

diff --git a/python/vyos/ifconfig/loopback.py b/python/vyos/ifconfig/loopback.py
index 7ebd13b54..2b4ebfdcc 100644
--- a/python/vyos/ifconfig/loopback.py
+++ b/python/vyos/ifconfig/loopback.py
@@ -75,5 +75,15 @@ class LoopbackIf(Interface):
         # Update IP address entry in our dictionary
         config.update({'address' : addr})
 
-        # now call the regular function from within our base class
+        # call base class
         super().update(config)
+
+        # 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()
+        # function. We will only enable the interface if 'up' was called as
+        # often as 'down'. This is required by some interface implementations
+        # as certain parameters can only be changed when the interface is
+        # in admin-down state. This ensures the link does not flap during
+        # reconfiguration.
+        state = 'down' if 'disable' in config else 'up'
+        self.set_admin_state(state)