Exceptions are seeing while Monitoring Ethernet interface kernel events using pyroute2 IPDB functionality

I am trying to monitor the kernel network interface(link) up or down events using pyroute2 IPDB functionality. Exceptions are seen while fetching the interface index information from the callback function. But here in the "msg" there is an index field. I coded based on this reference http://docs.pyroute2.org/ipdb.html. Any ideas to solve exception.

#!/usr/bin/python

import pyroute2

# Create Instance of IPDB
ipdb = pyroute2.IPDB()

action = 'RTM_NEWLINK'

def my_call_back(ipdb, msg, action):
   index = msg['index']
   print msg
   print index


ipdb.register_callback(my_call_back, mode='post')

while(True):
  pass

Expection: root@VirtualBox:/home/# python notification.py

{'index': 2, 'family': 0, '__align': (), 'header': {'pid': 0, 'length': 1276, 'flags': 0, 'error': None, 'type': 16, 'sequence_number': 0}, 'flags': 4098, 'ifi_type': 1, 'event': 'RTM_NEWLINK', 'change': 1, 'attrs': [('IFLA_IFNAME', 'eth0'), ('IFLA_TXQLEN', 1000), ('IFLA_OPERSTATE', 'DOWN'), ('IFLA_LINKMODE', 0), ('IFLA_MTU', 1500), ('IFLA_GROUP', 0), ('IFLA_PROMISCUITY', 0), ('IFLA_NUM_TX_QUEUES', 1), ('IFLA_GSO_MAX_SEGS', 65535), ('IFLA_GSO_MAX_SIZE', 65536), ('IFLA_NUM_RX_QUEUES', 1), ('IFLA_CARRIER', 0), ('IFLA_QDISC', 'pfifo_fast'), ('IFLA_CARRIER_CHANGES', 21), ('IFLA_PROTO_DOWN', 0), ('IFLA_MAP', {'dma': 0, 'base_addr': 0, 'irq': 0, 'mem_end': 0, 'port': 0, 'mem_start': 0}), ('IFLA_ADDRESS', '08:00:27:5f:7d:3e'), ('IFLA_BROADCAST', 'ff:ff:ff:ff:ff:ff'))
2
Exception in thread IPDB callback 140583224088768:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pyroute2/ipdb/main.py", line 968, in safe
    callback(*argv, **kwarg)
  File "notification.py", line 11, in my_call_back
    index = msg['index']
KeyError: 'index'

Exception in thread IPDB callback 140583224088768:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pyroute2/ipdb/main.py", line 968, in safe
    callback(*argv, **kwarg)
  File "notification.py", line 11, in my_call_back
    index = msg['index']
KeyError: 'index'

Testing:

 ifconfig <interface name> up/down
 ifconfig eth0 down
 ifconfig eth0 up

Solution

There are multiple kernel messages coming from the kernel to the callback function, when the link is made up or down. Some of the messages doesn't have "index" field due to which the key error is been seen. The below modified function shall resolve

def my_call_back(ipdb, msg, action):
   if 'index' in msg:
      index = msg['index']
      interface = ipdb.interfaces[index]
      print interface