Open Stack

On Mon, 7 Jul 2014, CARVER, PAUL wrote:

>
> Andrew Mann wrote:
> >What's the use case for an IPv6 endpoint? This service is just for instance metadata,
> >so as long as a requirement to support IPv4 is in place, using solely an IPv4 endpoint
> >avoids a number of complexities:
>
> The obvious use case would be deprecation of IPv4, but the question is when. Should I
> expect to be able to run a VM without IPv4 in 2014 or is IPv4 mandatory for all VMs?
> What about the year 2020 or 2050 or 2100? Do we ever reach a point where we can turn
> off IPv4 or will we need IPv4 for eternity?
>
> Right now it seems that we need IPv4 because cloud-init itself doesn’t appear to support
> IPv6 as a datasource. I’m going by this documentation
> http://cloudinit.readthedocs.org/en/latest/topics/datasources.html#what-is-a-datasource
> where the “magic ip” of 169.254.169.254 is referenced as well as some non-IP mechanisms.
>
> It wouldn’t be sufficient for OpenStack to support an IPv6 metadata address as long as
> most tenants are likely to be using a version of cloud-init that doesn’t know about IPv6
> so step one would be to find out whether the maintainer of cloud-init is open to the
> idea of IPv4-less clouds.

Most certainly, patches that are needed to cloud-init to support
functioning in a IPv4-less cloud are welcome.

>From an Ubuntu perspective, as long as the changes are safe from breaking
things, we'd also probably be able to get them into the official ubuntu
14.04 cloud images.

> If so, then picking a link local IPv6 address seems like the obvious thing to do and the
> update to Neutron should be pretty trivial. There are a few references to that
> “magic ip”
> https://github.com/openstack/neutron/search?p=2&q=169.254.169.254&ref=cmdform
> but the main one is the iptables redirect rule in the L3 agent:
> https://github.com/openstack/neutron/blob/master/neutron/agent/l3_agent.py#L684