R3.1 build 2: Alarm-gen failed due to ImportError: No module named kombu

on multi-node setup, alarm-gen on one of the analytics is not coming up due to the below issue :

Traceback (most recent call last):
  File "/usr/bin/contrail-alarm-gen", line 9, in <module>
    load_entry_point('opserver==0.1dev', 'console_scripts', 'contrail-alarm-gen')()
  File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 542, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2569, in load_entry_point
    return ep.load()
  File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2229, in load
    return self.resolve()
  File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2235, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/usr/lib/python2.7/dist-packages/opserver/alarmgen.py", line 47, in <module>
    from alarmgen_config_handler import AlarmGenConfigHandler
  File "/usr/lib/python2.7/dist-packages/opserver/alarmgen_config_handler.py", line 12, in <module>
    from config_handler import ConfigHandler
  File "/usr/lib/python2.7/dist-packages/opserver/config_handler.py", line 10, in <module>
    from cfgm_common.vnc_kombu import VncKombuClient
  File "/usr/lib/python2.7/dist-packages/cfgm_common/vnc_kombu.py", line 7, in <module>
    import kombu
ImportError: No module named kombu