[1.9.0] 500 error when deploying - KeyError amt

[Adam Collard]

Juju failed to start one of my machines on MAAS Version 1.9.0+bzr4533-0ubuntu1 (trusty1)

Snippet from apache log:
10.1.101.142 - - [22/Jan/2016:07:04:22 -0600] "POST /MAAS/api/1.0/nodes/node-31ecab2e-4b4a-11e4-a091-a0b3cce4ecca/?op=start HTTP/1.1" 500 249 "-" "Go 1.1 package http"

.. and regiond.log:

2016-01-22 07:05:03 [maasserver] ERROR: Traceback (most recent call last):
  File ".../django/core/handlers/base.py", line 112, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File ".../maasserver/utils/views.py", line 189, in
  view_atomic_with_post_commit_savepoint
    return view_atomic(*args, **kwargs)
  File ".../django/db/transaction.py", line 339, in inner
    return func(*args, **kwargs)
  File ".../maasserver/api/support.py", line 53, in __call__
    response = upcall(request, *args, **kwargs)
  File ".../django/views/decorators/vary.py", line 19, in inner_func
    response = func(*args, **kwargs)
  File ".../piston/resource.py", line 167, in __call__
    result = self.error_handler(e, request, meth, em_format)
  File ".../piston/resource.py", line 165, in __call__
    result = meth(request, *args, **kwargs)
  File ".../maasserver/api/support.py", line 201, in dispatch
    return function(self, request, *args, **kwargs)
  File ".../maasserver/api/nodes.py", line 496, in start
    form = Form(instance=node)
  File ".../maasserver/forms.py", line 838, in __init__
    self.set_up_power_type(data, instance)
  File ".../maasserver/forms.py", line 902, in set_up_power_type
    power_type]
KeyError: u'amt'

Note it looks like images were being updated at the same time - could be another variant of bug 1419041.

[Christian Reis (kiko)]

I don't think you mean bug 1410941.

[Adam Collard (adam-collard)]

Correct! Oops https://bugs.launchpad.net/maas/+bug/1419041

[Gavin Panella (allenap)]

I don't think this is related to bug 1419041.

The KeyError is arising from looking into a dict that's derived from a query to all connected clusters. It's something like: ask all clusters what power drivers they have, then merge.

I suspect there were, at the moment this exception occurred, no clusters connected.

There's certainly a problem here, which may or may not be a bug in MAAS — it could be a network problem, or the cluster was rebooting, for example — and I suspect this bug is a misleading symptom of that underlying problem.

[David Britton (dpb)]

FYI -- we always run with just one region/cluster controller, there
shouldn't be any real networking involved.​

[Andres Rodriguez (andreserl)]

We believe that this is not longer an issue in the latest releases of MAAS. If you believe this is still an issue, please re-open this bug report and target it accordingly.