Comment 10 for bug 1607412

Looking at the compute manager screen log, we can see that it is configured to query Neutron for its enabled extensions every 600 seconds (neutron.extension_sync_interval = 600):

http://logs.openstack.org/62/324262/3/gate/gate-grenade-dsvm-neutron-multinode/9af98c8/logs/subnode-2/old/screen-n-cpu.txt.gz?#_2016-07-25_10_04_12_778

So this compute manager queries Neutron for enabled extensions on 3 occasions (in each case, look at the following line):

http://logs.openstack.org/62/324262/3/gate/gate-grenade-dsvm-neutron-multinode/9af98c8/logs/subnode-2/old/screen-n-cpu.txt.gz?#_2016-07-25_10_04_25_201

http://logs.openstack.org/62/324262/3/gate/gate-grenade-dsvm-neutron-multinode/9af98c8/logs/subnode-2/old/screen-n-cpu.txt.gz?#_2016-07-25_10_15_04_869

http://logs.openstack.org/62/324262/3/gate/gate-grenade-dsvm-neutron-multinode/9af98c8/logs/subnode-2/old/screen-n-cpu.txt.gz?#_2016-07-25_10_25_13_705

The first two times, the list of extensions is: http://paste.openstack.org/show/543462/. The third, though, the list changed: http://paste.openstack.org/show/543463/. Looking in detail, the difference is that in the first two occasions, "dns-integration" is included. The last occasion, "dns-integration" is not included and "flavors" and "service-type" were added. Note that the failed port creation took place at 2016-07-25_10_24_49_258. That is right before the last Neutron extensions update, which doesn't return "dns_integration". So it seems that during the course the test, extensions are being added and removed from Neutron.