Evacuate fails when using cells - AttributeError: 'NoneType' object has no attribute 'count'

[Belmiro Moreira]

nova version: 2014.2.2
Using cells (parent - child setup)

How to reproduce:

nova evacuate <instance_uuid> <target_host>
ERROR: The server has either erred or is incapable of performing the requested operation. (HTTP 500) (Request-ID: req-a6666f20-182a-4acd-869a-1b23314b21d4)

LOG:

2015-05-12 23:17:27.274 8013 ERROR nova.api.openstack [req-a6666f20-182a-4acd-869a-1b23314b21d4 None] Caught error: 'NoneType' object has no attribute 'count'
Traceback (most recent call last):

  File "/usr/lib/python2.7/site-packages/oslo/messaging/rpc/dispatcher.py", line 134, in _dispatch_and_reply
    incoming.message))

  File "/usr/lib/python2.7/site-packages/oslo/messaging/rpc/dispatcher.py", line 177, in _dispatch
    return self._do_dispatch(endpoint, method, ctxt, args)

  File "/usr/lib/python2.7/site-packages/oslo/messaging/rpc/dispatcher.py", line 123, in _do_dispatch
    result = getattr(endpoint, method)(ctxt, **new_args)

  File "/usr/lib/python2.7/site-packages/nova/cells/manager.py", line 268, in service_get_by_compute_host
    service = response.value_or_raise()

  File "/usr/lib/python2.7/site-packages/nova/cells/messaging.py", line 406, in process
    next_hop = self._get_next_hop()

  File "/usr/lib/python2.7/site-packages/nova/cells/messaging.py", line 361, in _get_next_hop
    dest_hops = target_cell.count(_PATH_CELL_SEP)

AttributeError: 'NoneType' object has no attribute 'count'

[Adrien Vergé (adrienverge)]

It seems like this error is a side effect of a missing cell routing path. Maybe commit 80f9252 needs to be backported to Juno, in order to raise a proper NovaException (which is caught and handled by the API, instead of generating a HTTP 500).

[Sean Dague (sdague)]

Automatically discovered version juno in description. If this is incorrect, please update the description to include 'nova version: ...'