boot fails on network /w only an ipv6 subnet, AttributeError: 'NoneType' object has no attribute 'get'

[Adam Gandelman]

On rug startup, the devstack-created router appliance fails to spawn with the following traceback in nova:

ams': None})]| from (pid=17775) _allocate_network_async /opt/stack/nova/nova/compute/manager.py:1527
2015-07-20 14:07:26.462 ERROR nova.compute.manager [req-057f87b7-b0b5-45e7-b6f8-5c6cbb7a2be0 neutron service] [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] Instance failed to spawn
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] Traceback (most recent call last):
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] File "/opt/stack/nova/nova/compute/manager.py", line 2110, in _build_resources
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] yield resources
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] File "/opt/stack/nova/nova/compute/manager.py", line 1982, in _build_and_run_instance
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] block_device_info=block_device_info)
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 2409, in spawn
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] admin_pass=admin_password)
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 2882, in _create_image
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] content=files, extra_md=extra_md, network_info=network_info)
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] File "/opt/stack/nova/nova/api/metadata/base.py", line 156, in __init__
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] self.network_metadata = netutils.get_network_metadata(network_info)
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] File "/opt/stack/nova/nova/virt/netutils.py", line 229, in get_network_metadata
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] if subnet_v4.get('ips'):
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] AttributeError: 'NoneType' object has no attribute 'get'
2015-07-20 14:07:26.462 TRACE nova.compute.manager [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7]
2015-07-20 14:07:26.464 INFO nova.compute.manager [req-057f87b7-b0b5-45e7-b6f8-5c6cbb7a2be0 neutron service] [instance: 2e5ff228-9d7b-436a-8053-6fcd11b02eb7] Terminating instance

A little digging shows that this recently merged into nova and is likely the cause of the breakage: https://review.openstack.org/#/c/102649/

[Adam Gandelman (gandelman-a)]

This is a nova bug introduced /w https://review.openstack.org/#/c/102649/ that prevents instances from booting unless their network has an ipv4 subnet. Instances on a network that only have a single ipv6 subnet will fail on this AttributeError

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/203846

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/203846
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=6cce41eaa3e73cad9d04255521634f1af08267b6
Submitter: Jenkins
Branch: master

commit 6cce41eaa3e73cad9d04255521634f1af08267b6
Author: Adam Gandelman <email address hidden>
Date: Mon Jul 20 15:44:23 2015 -0700

    Only work with ipv4 subnet metadata if one exists

    This code currently throws an exception and fails the build if an
    instance boots on a network without a v4 subnet. Protect against
    this by checking it has a ipv4 subnet.

    Change-Id: I7c5de308b557293f5ac6b919d5566ace809ce200
    Closes-bug: #1476402