[Rdo-list] DNS resolver problems w/ instack-virt-setup

[Marius Cornea]

Hi Lars,

192.168.122.1 is set on the virbr0 interface on the host (default
libvirt net) where under/overcloud VMs are running. The undercloud
node (instack VM) has 2 interfaces - one in the virbr0
bridge(192.168.122.0/24 subnet) and the other in the brbm ovs bridge
(192.0.2.0/24 subnet).  The overcloud nodes have one interface in the
brbm bridge and route the traffic through the undercloud node. You can
check that default gw on overcloud nodes is 192.0.2.1 (eth1 of instack
VM). The undercloud node masquerades all traffic coming from
192.0.2.0/24 so the overcloud nodes can get external connectivity,
including to 192.168.122.1 which handles the dns queries.

On Fri, Apr 17, 2015 at 6:06 PM, James Slagle <jslagle at redhat.com> wrote:
> On Fri, Apr 17, 2015 at 11:08:25AM -0400, Lars Kellogg-Stedman wrote:
>> On the overcloud nodes deployed by instack-virt-setup,
>> /etc/resolv.conf looks like this:
>>
>>     search openstacklocal
>>     nameserver 192.168.122.1
>>
>> That's not a useful address for either of these nodes, on which
>> external connectivity -- at least on the controller -- is via
>> eth0/br-ex on the 192.0.2.0/24 network.  Even worse, on the controller
>> "192.168.122.1" is actually the address of the local "virbr0"
>> interface configured by libvirt, so DNS requests aren't going to go
>> anywhere useful.
>>
>> There are obviously a number of ways to fix this, including setting up
>> dnsmasq on the undercloud node and using that instead.  How is this
>> supposed to work?  Did the deployments script screw up, or did I miss
>> something in the docs?
>
> I think we might have a couple of patches posted that are in review that might
> help with these issues:
>
> https://review.gerrithub.io/230339
> https://review.gerrithub.io/230143
>
> Also makes sure ip forwarding is enabled on the host machine:
> sudo sysctl net.ipv4.ip_forward=1
> (This needs to get added to the documentation).
>
> Thanks for helping to try things out.
>
> --
> -- James Slagle
> --
>
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