openstack team mailing list archive

[Ryan Lane <rlane@xxxxxxxxxxxxx>]

> EC2 has a feature where if an instance has a fixed IP of 10.0.0.1, and a
> floating IP of 1.2.3.4. All DNS lookups performed against the DNS name for
> 1.2.3.4, from within the same region, will return 10.0.0.1.
>
> E Hammond from Alestic probably explains it better :)
>
>> When an EC2 instance queries the external DNS name of an Elastic IP, the
>> EC2 DNS server returns the internal IP address of the instance to which the
>> Elastic IP address is currently assigned.
>
> While this has advantages for traffic accounting in EC2, It can additionally
> provide a fix for the inability of an OpenStack instance to reach it's own
> floating IP address. (Try ping'ing a floating IP from the instance
> that floating IP is assigned to.. It will fail).
>
> I hope this explains it a tad better :)
>

This would indeed be a great feature to have, but I don't think that
it's something that should necessarily be handled by this blueprint.
This is more of a driver-level feature.

One way I can think of implementing this at the driver level is to do
it when floating IP addresses are associated with instances, or when a
DNS address is added to the associated IP. At this point the driver
can add an entry to another DNS server. Anycast can be configured to
let one server handle requests from the instances, and non-instance
requests can be handled by the normal DNS server.

- Ryan