Having a subnet with no dns_server configured at all makes internal DNS not working

Bug #1774371 reported by Miguel Angel Ajo
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
networking-ovn
Invalid
Undecided
Unassigned

Bug Description

This is a behavioural difference with ml2/ovs and the dhcp-agent.

In the reference implementation, when a subnet is created, if no dns servers is provided the dhcp resolution will point to the dnsmasq port instance, which will resolv internal dns requests, and forward the unknown ones upstream.

In the case of networking-ovn, we don't create a dhcp port for dhcp purposes. We just capture instance outgoing DNS queries, and respond to the internal ones, while the external ones are sent back to network. such implementation requires that at least one dns server has been configured via DHCP to the instance. But if during subnet creation the dns-server / dns-servers field was left unspecified, the internal dns server won't work.

A temporary workaround is configuring the upstream dns server when creating the subnet:

neutron subnet-update 4db68a2b-62e9-4660-9163-3e512eb47b2b --dns-nameserver 8.8.8.8

Revision history for this message
Miguel Angel Ajo (mangelajo) wrote :
Changed in networking-ovn:
status: New → Confirmed
status: Confirmed → Incomplete
status: Incomplete → Invalid
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