Juju/MAAS does not provide feedback when there are no available nodes are found

[Andres Rodriguez]

This bug was found when debugging for bug in [1].

The case being is that when we deploy a node via juju, and for whatever reason no available MAAS node is found, juju seems to have successfully deployed a service when it hasn't really.

1. Juju deploy shows that the service has been successfully deployed:

node@node:/var/log/maas$ juju deploy ubuntu
2013-03-13 15:57:16,067 INFO Searching for charm cs:precise/ubuntu in charm store
2013-03-13 15:57:17,253 INFO Connecting to environment...
2013-03-13 15:57:18,804 INFO Connected to environment.
2013-03-13 15:57:19,302 INFO Charm deployed as service: 'ubuntu'
2013-03-13 15:57:19,303 INFO 'deploy' command finished successfully

2. On a juju status, juju shows a node pending:
node@node:/var/log/maas$ juju status
2013-03-13 16:01:02,145 INFO Connecting to environment...
2013-03-13 16:01:03,659 INFO Connected to environment.
machines:
  0:
    agent-state: running
    dns-name: zookeeper.hdl
    instance-id: /MAAS/api/1.0/nodes/node-90ab5638-8c01-11e2-bda5-52540083b879/
    instance-state: unknown
  1:
    instance-id: pending
services:
  ubuntu:
    charm: cs:precise/ubuntu-0
    relations: {}
    units:
      ubuntu/1:
        agent-state: pending
        machine: 1
        public-address: null

3. Hence, no node is allocated (hence the WebUI doesn't show the allocated node). However, the maas.log does show the following error:

  File "/usr/lib/python2.7/dist-packages/piston/resource.py", line 166, in __call__
    result = self.error_handler(e, request, meth, em_format)
  File "/usr/lib/python2.7/dist-packages/piston/resource.py", line 164, in __call__
    result = meth(request, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/api.py", line 308, in dispatch
    return function(self, request, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/api.py", line 945, in acquire
    raise NodesNotAvailable("No matching node is available.")
NodesNotAvailable: No matching node is available.

This is unfortunate because for juju's eyes, a node was successfully deployed/allocated, while for MAAS eye's it hasn't. However, juju should show that no nodes are available and do not add a node that hasn't been allocated.

[1] https://bugs.launchpad.net/maas/+bug/1154803

[Julian Edwards (julian-edwards)]

Maas returns a 409 CONFLICT when there's no node available. This is purely a Juju problem.