[Bug 1857026] Re: OVN doesn't seem to support reverse DNS lookups for instances
Frode Nordahl
1857026 at bugs.launchpad.net
Mon Mar 21 10:52:33 UTC 2022
Deployed focal-wallaby from charm-neutron-api-plugin-ovn gate tests and patched Neutron for some unresolved issues at Wallaby. The need to do that is unfortunate but this verificat
ion is about the OVN pacakges, so let's focus on them.
With two instances running we can see the following information in the OVN DB:
$ sudo ovn-nbctl list dns
_uuid : a62d480f-e5ad-421e-9e8a-ab4072232331
external_ids : {ls_name=neutron-7d2d7f7e-ebb9-4625-a2ab-8bb6647f1988}
records : {"182.0.168.192.in-addr.arpa"=zaza-neutrontests-ins-1.openstack.example, "239.0.168.192.in-addr.arpa"=zaza-neutrontests-ins-2.openstack.example, zaza-neutrontests-ins-1="192.168.0.182", zaza-neutrontests-ins-1.openstack.example="192.168.0.182", zaza-neutrontests-ins-2="192.168.0.239", zaza-neutrontests-ins-2.openstack.example="192.168.0.239"}
Control test:
>From instance forward DNS lookups of other instance names work:
$ host zaza-neutrontests-ins-1.openstack.example
zaza-neutrontests-ins-1.openstack.example has address 192.168.0.182
But reverse DNS lookup of other instance IP does not work:
$ host 192.168.0.182
Host 182.0.168.192.in-addr.arpa. not found: 3(NXDOMAIN)
Upgrade to packages from -proposed:
$ juju run --application ovn-chassis 'dpkg -l | grep ovn'
- Stdout: |
ii neutron-ovn-metadata-agent 2:18.1.1-0ubuntu2~cloud0 all Neutron is a virtual network service for Openstack - OVN metadata agent
ii ovn-common 20.12.0-0ubuntu3.1~cloud0 amd64 OVN common components
ii ovn-host 20.12.0-0ubuntu3.1~cloud0 amd64 OVN host components
UnitId: ovn-chassis/0
- Stdout: |
ii neutron-ovn-metadata-agent 2:18.1.1-0ubuntu2~cloud0 all Neutron is a virtual network service for Openstack - OVN metadata agent
ii ovn-common 20.12.0-0ubuntu3.1~cloud0 amd64 OVN common components
ii ovn-host 20.12.0-0ubuntu3.1~cloud0 amd64 OVN host components
UnitId: ovn-chassis/1
Confirm updated packages work:
$ sudo systemctl restart systemd-resolved
$ host zaza-neutrontests-ins-1.openstack.example
zaza-neutrontests-ins-1.openstack.example has address 192.168.0.182
$ host 192.168.0.182
182.0.168.192.in-addr.arpa domain name pointer zaza-neutrontests-ins-1.openstack.example.
** Tags removed: verification-needed verification-wallaby-needed
** Tags added: verification-done verification-wallaby-done
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https://bugs.launchpad.net/bugs/1857026
Title:
OVN doesn't seem to support reverse DNS lookups for instances
Status in charm-ovn-central:
Invalid
Status in Ubuntu Cloud Archive:
Fix Released
Status in Ubuntu Cloud Archive wallaby series:
Fix Committed
Status in ovn package in Ubuntu:
Fix Released
Status in ovn source package in Focal:
Fix Committed
Status in ovn source package in Hirsute:
Won't Fix
Bug description:
[Impact]
At Focal we took a stance that moving forward new deployments of Charmed OpenStack should use OVN as the SDN. For clouds upgrading, Focal is also the point for which a migration from ML2/OVS to ML2/OVN should take place before further upgrades are applied.
The current lack of support for reverse DNS lookup for IP addresses
belonging to project instances would prevent users with applications
depending on this feature to commence new deployments or upgrade
through Focal and beyond.
[Test Plan]
Deploy a Charmed OpenStack and perform forward and reverse DNS lookups for instance names and addresses with the old and new packages to confirm.
[Regression Potential]
The instance DNS resolution in OVN works by looking up records in the OVN Southbound database. The CMS adds records for both forward and reverse lookups and the OVN controller needs to know how to look for them. The included patches have been available for several upstream releases without any reported issues. In addition we have been running internal clouds with these patches without issues.
[Original Bug Description]
There's an upstream bug that mentions this during implementation of regular DNS lookups - https://bugzilla.redhat.com/show_bug.cgi?id=1503521
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