Hypervisors returns TemplateSyntaxError instead of error message

[Pawel Palucki]

When trying to list hypervisor at /admin/hypervisors/
I got TemplateSyntaxError. It happens when novaclient (nova-api)
cannot fulfil the request.

The exception in Horizon:

Error while rendering table rows.
Traceback (most recent call last):
  File "/opt/stack/horizon/horizon/tables/base.py", line 1751, in get_rows
    for datum in self.filtered_data:
TypeError: 'NoneType' object is not iterable
Internal Server Error: /admin/hypervisors/
Traceback (most recent call last):
  ...
  File "/opt/stack/horizon/horizon/tables/base.py", line 1751, in get_rows
    for datum in self.filtered_data:
TemplateSyntaxError: 'NoneType' object is not iterable

IMO it should be more robust and just return error message. It would be more
consistent with how other views handles unavailable services.

To reproduce the error it is enough that novaclient raise exception. Example for this
is my case was when zookeeper as servicegroup driver is used, but
nova-conductor hasn't yet prepared the required namespace (because of bug [1]) - which
ends that nova-api had internal error:

nova.api.openstack ServiceGroupUnavailable: The service from servicegroup driver
ZooKeeperDriver is temporarily unavailable.

This overall result is that whole hypervisor list page was unaccessible only because is was not possible to list nova services.

[1] https://bugs.launchpad.net/nova/+bug/1389782

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/134277

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/134277
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=5c4e827568be429ac5227a950c9f24c578ca8fd8
Submitter: Jenkins
Branch: master

commit 5c4e827568be429ac5227a950c9f24c578ca8fd8
Author: Pawel Palucki <email address hidden>
Date: Mon Nov 10 20:56:51 2014 +0100

    Fix TemplateSyntaxError at hypervisors view

    If somehow nova API service-list isn't available, listing
    hypervisors at /admin/hypervisors/ ends with TemplateSyntaxError.

    Expected result is that the page should load but user will
    see empty list and error message.

    This fix is based on idea found in other views:

    openstack_dashboard/dashboards/admin/...
    images/views.py
    aggregate/views.py
    falvors/views.pu

    that on any exception while getting data (get_data), we just
    return empty list and handle exception to display error message.

    Closes-Bug: #1392316

    Change-Id: Ia665111185abecab6a96e6c72a6088cf2fa2e02b

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/200487

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/kilo
Review: https://review.openstack.org/201368

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lin Hua Cheng (<email address hidden>) on branch: stable/kilo
Review: https://review.openstack.org/201368
Reason: this was fixed in Kilo, wrong backport

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/200487
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=184f5a6380567e902b06e6013bdb2a757ff8c9b3
Submitter: Jenkins
Branch: stable/juno

commit 184f5a6380567e902b06e6013bdb2a757ff8c9b3
Author: Pawel Palucki <email address hidden>
Date: Mon Nov 10 20:56:51 2014 +0100

    Fix TemplateSyntaxError at hypervisors view

    If somehow nova API service-list isn't available, listing
    hypervisors at /admin/hypervisors/ ends with TemplateSyntaxError.

    Expected result is that the page should load but user will
    see empty list and error message.

    This fix is based on idea found in other views:

    openstack_dashboard/dashboards/admin/...
    images/views.py
    aggregate/views.py
    falvors/views.pu

    that on any exception while getting data (get_data), we just
    return empty list and handle exception to display error message.

    Closes-Bug: #1392316

    Change-Id: Ia665111185abecab6a96e6c72a6088cf2fa2e02b
    (cherry picked from commit 5c4e827568be429ac5227a950c9f24c578ca8fd8)