Impossible attach detached port to another instance

[Sergey Kraynev]

The follow scenario leads to error:
 - create independent port in neutron
 - boot VM in nova
 - attach port to VM via nova interface-attach. As result dns_name of port will be updated and port be attached to VM
 - detach port from VM via nova interface-detach. As result port will be detached, BUT dns_name will be still as name of VM.

if you try to attach this port to another VM you will get error, that it's not possible to attach port.

The same issue happens for Heat stack, when we have VM+port and execute update replace for Server.

[Sergey Kraynev (skraynev)]

This feature was added in mitaka-3, so if we decide to fix it in N1, we need to backport it.

[Sergey Kraynev (skraynev)]

I have added it to nova and neutron, because issue is related with feature, which affects both projects.

[Timofey Durakov (tdurakov)]

This is Nova issue.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/308389

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/308389
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=fc66e7eb411eb8e99767c062ab8d0263738d5558
Submitter: Jenkins
Branch: master

commit fc66e7eb411eb8e99767c062ab8d0263738d5558
Author: Timofey Durakov <email address hidden>
Date: Wed Apr 20 17:58:23 2016 +0300

    Clean port dns_name in case of port detach

    In case of port detach dns_name should be also
    updated in Neutron

    Change-Id: I65edb33b955a91d1701fc91cb9fae0a5f26d4e46
    Closes-Bug: #1572593

[Richard Theis (rtheis)]

This fix may have broken networking-ovn. Please see https://bugs.launchpad.net/networking-ovn/+bug/1575195 for details.

[Matt Riedemann (mriedem)]

If we backport the fix for this in nova we also have to backport the fix for the bug that it introduced:

https://review.openstack.org/#/c/310474/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/mitaka
Review: https://review.openstack.org/310489

[bailin.zhang (bailin-zhang)]

https://bugs.launchpad.net/nova/+bug/1553889 is similar with this bug.
Not so simply,I think we can not clear dns_name at detached-interface.
the dns_name of port should be retained ,when it was assigned by the user.

At the doc: http://docs.openstack.org/mitaka/networking-guide/adv-config-dns.html
"Instead of having the Compute service create the port for the instance, the user might have created it and assigned a value to its dns_name attribute. In this case, the value assigned to the dns_name attribute must be equal to the value that Compute service will assign to the instance’s hostname, in this example my-vm. Otherwise, the instance boot will fail"

[Davanum Srinivas (DIMS) (dims-v)]

This issue was fixed in the openstack/nova 14.0.0.0b1 development milestone.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/310489
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=66334ed7b52cd1bb21e507ea5da384cefcadc138
Submitter: Jenkins
Branch: stable/mitaka

commit 66334ed7b52cd1bb21e507ea5da384cefcadc138
Author: Timofey Durakov <email address hidden>
Date: Wed Apr 20 17:58:23 2016 +0300

    Clean port dns_name in case of port detach

    In case of port detach dns_name should be also
    updated in Neutron

    Change-Id: I65edb33b955a91d1701fc91cb9fae0a5f26d4e46
    Closes-Bug: #1572593
    (cherry picked from commit fc66e7eb411eb8e99767c062ab8d0263738d5558)

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/nova 13.1.0 release.