T4825: Verify if veth interface not used in conf before deleting

Prevent to delete interface "vethX" which used for another
interface as "vethY peer-name vethX"

set interfaces virtual-ethernet veth0 peer-name 'veth1'
set interfaces virtual-ethernet veth1 peer-name 'veth0'
commit
delete interfaces virtual-ethernet veth0
commit

1 files changed, 7 insertions, 0 deletions

diff --git a/src/conf_mode/interfaces-virtual-ethernet.py b/src/conf_mode/interfaces-virtual-ethernet.py
index b1819233c..53422ad2d 100755
--- a/src/conf_mode/interfaces-virtual-ethernet.py
+++ b/src/conf_mode/interfaces-virtual-ethernet.py
@@ -53,6 +53,13 @@ def get_config(config=None):
 def verify(veth):
     if 'deleted' in veth:
         verify_bridge_delete(veth)
+        # Prevent to delete veth interface which used for another "vethX peer-name"
+        for iface, iface_config in veth['other_interfaces'].items():
+            if veth['ifname'] in iface_config['peer_name']:
+                ifname = veth['ifname']
+                raise ConfigError(
+                    f'Cannot delete "{ifname}" used for "interface {iface} peer-name"'
+                )
         return None
 
     verify_vrf(veth)