vpp: T8913: Skip bond teardown for non-structural config changes

VPP bond teardown was triggered on every commit regardless of
what changed, dropping all subinterfaces and BGP sessions even
for trivial changes like descriptions or IP addresses.
Only mode, hash-policy and mac_address require full recreation
since VPP has no in-place update API for these; all other
changes are now applied incrementally.

2 files changed, 26 insertions, 5 deletions

diff --git a/python/vyos/ifconfig/vpp/bond.py b/python/vyos/ifconfig/vpp/bond.py
index b3bcce449..cece5560d 100644
--- a/python/vyos/ifconfig/vpp/bond.py
+++ b/python/vyos/ifconfig/vpp/bond.py
@@ -17,6 +17,7 @@
 
 from vyos.ifconfig import Interface
 from vyos.ifconfig.vpp.interface import VPPInterface
+from vyos.utils.dict import dict_search
 
 
 class VPPBondInterface(Interface, VPPInterface):
@@ -135,13 +136,24 @@ class VPPBondInterface(Interface, VPPInterface):
             # Delete bonding interface
             self.delete_bond()
 
+            self.index = None
+
     def update(self, config):
         # Add bond interface
-        self.add_bond()
+        if self.index is None:
+            self.add_bond()
+
+        # Delete removed members
+        members = self.get_members()
+        config_members = dict_search('member.interface', config, default=[])
+        for member in members:
+            if member not in config_members:
+                self.detach_member(interface=member)
 
         # Add members to bond
-        for member in config.get('member', {}).get('interface', []):
-            self.add_member(interface=member)
+        for member in config_members:
+            if member not in members:
+                self.add_member(interface=member)
 
         # Apply VPP-specific interface settings
         VPPInterface.update(self, config)
diff --git a/src/conf_mode/vpp_interfaces_bonding.py b/src/conf_mode/vpp_interfaces_bonding.py
index c7fd43bb4..932287a03 100644
--- a/src/conf_mode/vpp_interfaces_bonding.py
+++ b/src/conf_mode/vpp_interfaces_bonding.py
@@ -18,6 +18,7 @@
 
 from vyos.config import Config
 from vyos.configdict import get_interface_dict
+from vyos.configdict import is_node_changed
 from vyos.configdep import set_dependents, call_dependents
 from vyos.configverify import verify_mtu_ipv6
 from vyos import ConfigError
@@ -108,6 +109,12 @@ def get_config(config=None) -> dict:
         no_tag_node_value_mangle=True,
     )
 
+    iface_path = ['interfaces', 'vpp', 'bonding', ifname]
+    rebuild_required_nodes = ['mode', 'hash-policy', 'mac']
+    for node in rebuild_required_nodes:
+        if is_node_changed(conf, iface_path + [node]):
+            config.update({'rebuild_required': {}})
+
     config['bond_members'] = deps_bond_dict(conf)
 
     # Dependency
@@ -225,10 +232,12 @@ def apply(config):
 
     ifname = config.get('ifname')
     bond = VPPBondInterface(ifname, config)
-    bond.remove()
+
+    if 'deleted' in config or 'rebuild_required' in config:
+        bond.remove()
 
     if 'deleted' in config:
-        return
+        return None
 
     bond.update(config)