Dashboard fails on precise due to version of python-six

[Liam Young]

The dashboard returns a 500 when installed on precise due to the installed version of python-six being too low.

The installed version of python-six is 1.1.0-2 but after the charm has run 1.5.2-1 is available from the cloud archive. Installing 1.5.2-1 and restarting apache2 solves the problem.

This problem appears to be because the installation of python-six is triggered by the import of charmhelpers which means it is installed before the cloud archive is added as a source. python-six is subsequently not updated.

When a 500 is returned the apache error log shows:

[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] mod_wsgi (pid=717): Exception occurred processing WSGI script '/usr/share/openstack-dashboard/openstack_dashboard/wsgi/django.wsgi'.
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] Traceback (most recent call last):
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/django/core/handlers/wsgi.py", line 187, in __call__
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] self.load_middleware()
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py", line 44, in load_middleware
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] for middleware_path in settings.MIDDLEWARE_CLASSES:
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/django/conf/__init__.py", line 54, in __getattr__
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] self._setup(name)
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/django/conf/__init__.py", line 49, in _setup
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] self._wrapped = Settings(settings_module)
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/django/conf/__init__.py", line 128, in __init__
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] mod = importlib.import_module(self.SETTINGS_MODULE)
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/django/utils/importlib.py", line 40, in import_module
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] __import__(name)
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/settings.py", line 246, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from openstack_dashboard import policy
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/policy.py", line 27, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from openstack_auth import utils as auth_utils
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/openstack_auth/utils.py", line 22, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from keystoneclient.v2_0 import client as client_v2
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/keystoneclient/v2_0/__init__.py", line 2, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from keystoneclient.v2_0.client import Client
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/keystoneclient/v2_0/client.py", line 18, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from keystoneclient.auth.identity import v2 as v2_auth
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/keystoneclient/auth/identity/v2.py", line 19, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from keystoneclient import access
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/keystoneclient/access.py", line 21, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] from keystoneclient import service_catalog
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] File "/usr/lib/python2.7/dist-packages/keystoneclient/service_catalog.py", line 27, in <module>
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] @six.add_metaclass(abc.ABCMeta)
[Tue Feb 10 19:08:14 2015] [error] [client 10.5.13.191] AttributeError: 'module' object has no attribute 'add_metaclass'