vyos.ifconfig: T7018: drop 'iftype' class attribute (#4280)

Under very rare cases we can run into a race condition where interfaces are
still in creation phase but are already referenced..

This can trigger:

  File "/usr/libexec/vyos/conf_mode/system_conntrack.py", line 270, in <module>
    apply(c)
  File "/usr/libexec/vyos/conf_mode/system_conntrack.py", line 249, in apply
    call_dependents()
  File "/usr/lib/python3/dist-packages/vyos/configdep.py", line 147, in call_dependents
    f()
  File "/usr/lib/python3/dist-packages/vyos/configdep.py", line 118, in func_impl
    run_config_mode_script(script, config)
  File "/usr/lib/python3/dist-packages/vyos/configdep.py", line 106, in run_config_mode_script
    mod.verify(c)
  File "/usr/libexec/vyos//conf_mode/service_conntrack-sync.py", line 72, in verify
    if len(get_ipv4(interface)) < 1:
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/vyos/template.py", line 458, in get_ipv4
    return Interface(interface).get_addr_v4()
           ^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/interface.py", line 334, in __init__
    if not self.iftype:
    ^^^^^^^^^^^

  AttributeError: 'Interface' object has no attribute 'iftype'

This commit removes the code path in question and the class attribute check.
The reason for the iftype attribute in the past was a common _create() method
serving for all interface types. As we already have a lot of derived
implementations and not all honor the classes iftype/type member - or even
worse honor it only in 50% of the occurrences it's time to drop it.

1 files changed, 5 insertions, 1 deletions

diff --git a/python/vyos/ifconfig/loopback.py b/python/vyos/ifconfig/loopback.py
index e1d041839..13e8a2c50 100644
--- a/python/vyos/ifconfig/loopback.py
+++ b/python/vyos/ifconfig/loopback.py
@@ -22,16 +22,20 @@ class LoopbackIf(Interface):
     uses to communicate with itself.
     """
     _persistent_addresses = ['127.0.0.1/8', '::1/128']
-    iftype = 'loopback'
     definition = {
         **Interface.definition,
         **{
             'section': 'loopback',
             'prefixes': ['lo', ],
             'bridgeable': True,
+            'eternal': 'lo$',
         }
     }
 
+    def _create(self):
+        # we can not create this interface as it is managed by the Kernel
+        pass
+
     def remove(self):
         """
         Loopback interface can not be deleted from operating system. We can