Setting up internal DNS resolution with OVN

OVN supports Neutron internal DNS resolution.


For general information on OVN, refer to the main Open Virtual Network (OVN) page.

To configure:

juju config neutron-api enable-ml2-dns=true
juju config neutron-api dns-domain=openstack.example.
juju config neutron-api-plugin-ovn dns-servers=""


The value for the dns-domain configuration option must not be set to ‘openstack.local.’ as doing so will effectively disable the feature.

The provided value must also end with a ‘.’ (dot).

When you set enable-ml2-dns to ‘true’ and set a value for dns-domain, Neutron will add details such as instance name and DNS domain name to each individual Neutron port associated with instances. The OVN ML2 driver will populate the DNS table of the Northbound and Southbound databases:

# ovn-sbctl list DNS
_uuid               : 2e149fa8-d27f-4106-99f5-a08f60c443bf
datapaths           : [b25ed99a-89f1-49cc-be51-d215aa6fb073]
external_ids        : {dns_id="4c79807e-0755-4d17-b4bc-eb57b93bf78d"}

records             : {"c-1"="", "c-1.openstack.example"=""}

On the chassis, OVN creates flow rules to redirect UDP port 53 packets (DNS) to the local ovn-controller process:

cookie=0xdeaffed, duration=77.575s, table=22, n_packets=0, n_bytes=0, idle_age=77, priority=100,udp6,metadata=0x2,tp_dst=53 actions=controller(,pause),resubmit(,23)
cookie=0xdeaffed, duration=77.570s, table=22, n_packets=0, n_bytes=0, idle_age=77, priority=100,udp,metadata=0x2,tp_dst=53 actions=controller(,pause),resubmit(,23)

The local ovn-controller process then decides if it should respond to the DNS query directly or if it needs to be forwarded to the real DNS server.