[libvirt] interface "peer address" patches are broken

[Laine Stump]

On 04/26/2016 06:55 AM, Vasiliy Tolstov wrote:
>
> Yes,I see that peer disappeared in XML,but works on first start...
> Also I agree that address more for guest side and not host,do you have 
> some suggestions for me how to fix that before release?
>

The simplest fix would be to just swap peer and address in the 
set-address call for QEMU, but the fact that the problem didn't leap out 
at anyone indicates that the current name "peer" may not be the best 
choice (even though that's what it really is in the netlink message that 
sets the addresses; of course that *won't* be the case after it's fixed 
- "address" will be set as "peer", and "peer" as "address"). So, as I 
suggested in my earlier message, maybe we can come up with a better name 
for what is now called "peer" ("address" must stay the same, since it 
has already been in several releases). Does "hostAddress" sound okay?

Either of these patches (the one to fix the missing attribute in the XML 
or the one to rename the attribute) could be pushed even after DV begins 
the freeze period for the release - they qualify as bug fixes.

(I actually already have a patch to fix the missing peer attribute in 
the XML, and am testing it, so the big question is whether to change the 
name from "peer" to something more accurate, and if so, what to change 
it to).

> 25 Апр 2016 г. 8:57 PM пользователь "Laine Stump" <laine at laine.org 
> <mailto:laine at laine.org>> написал:
>
>     I haven't had the time to fix it yet, but wanted to point out that
>     the patches that are supposed to support setting the peer address
>     of tap/macvlan devices do not work. The problem is that the peer
>     attribute isn't being included when the XML for a a domain
>     interface is being formatted.
>
>     I also sent the following message last week as a followup to the
>     patch series; possibly it wasn't noticed for that reason:.
>
>     I'll make a patch to fix the formatting when I can so that I can
>     test my theory about address vs. peer on lxc  vs qemu. But if it's
>     fixed by someone else in the meantime, all the better :-)
>
>
>     On 04/20/2016 12:36 PM, Laine Stump wrote:
>
>         Something I've found myself worrying about lately while
>         driving in the car or nodding off to sleep - are the "address"
>         and "peer" attributes effectively used in the same way for all
>         network connection types and both hypervisors? I think the
>         answer may be "no", and if so we need to fix that before they
>         go out in a release.
>
>         In particular, when an lxc domain's interface has:
>
>            <ip address='192.168.128.1'/>
>
>         That is the IP address seen by the guest, not the host. So I
>         would assume that if an LXC domain had:
>
>
>            <ip address='192.168.128.1' peer='192.168.128.2'/>
>
>         that 192.168.128.1 would still be the IP address see by the
>         guest, and 192.168.128.2 would be the IP address on the host
>         side; and it should be the same for qemu.
>
>         >From what I can see of the code, though, on a qemu domain,
>         the IP address is set for the tap device's own IP, meaning
>         that it would show up on the *host* side, while the peer
>         address would be what the host expects to be at the other end
>         of the tap device (i.e. the guest side), so the two attributes
>         are used for the *opposite* end of the PTP link in lxc vs. qemu.
>
>         I think that, instead, the "address" attribute should *always*
>         be the IP address that is seen/used by the guest, and the
>         "peer" attribute should be the IP address that is seen/used by
>         the host. (perhaps "peer" could be replaced with some other
>         name, like "host" or "hostAddress" to avoid confusion? (don't
>         like either of those alternatives, but I don't really like
>         peer either)).
>
>         Aside from that, I can see that these patches have been pushed
>         in the code that I'm running, and I've been trying to add
>         "peer='blah'" to interface IP addresses on my test machine,
>         but it's just removed from the config. Have you tested what
>         got pushed? Has something gone wrong?
>
>         Since there hasn't been a release with these patches included
>         yet, there is still time to fix it at least to be consistent
>         (assuming that my suspicions are correct; I've been unable to
>         test it myself for the reason above).
>

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