[Spread-users] Implementing node-driven ip aliasing in Spread/Wackamole

David Turland david.turland at shazamteam.com
Fri May 3 08:21:07 EDT 2002

On Friday 03 May 2002 12:57, Theo Schlossnagle <jesus at omniti.com> wrote:
> On Friday, May 3, 2002, at 07:09 AM, David Turland wrote:
> > Wackamole:
> > ---------------
> > This seems the best contender. wackamole.c certainly offers enough
> > hooks.
> The CVS version of wackamole should suit your purposes completely if the
> release version does not.  You shouldn't need to make any changes.  Run
> wackamole on all you N master nodes with a single VIP and be done with
> it.  I do this on firewall machines (where you have N machines and need
> 1 and only 1 to have the "master IP").  It works like a charm.
> > Mods to wackamole.c
> > ---------------------------
> >
> > - remove the sp_join ('wackamole') call in wackamole.c but still run as
> > normal
> > (need the root privileges it is empowered with and don't want to run my
> > app
> > as root!)
> I don't know why it wouldn't join the wackamole group... That is pretty
> essential to its operation.  You run wackamole as a separate process
> from your app.  If you app get's hosed or confused or broken, it can
> always trigger wackamole to give up it's IP address to another master.
> One of the nice things about Spread is that it runs on a daemon/machine
> model.  There is no problem with running a wackamole process and your
> app connected to the same instance of Spread on the local box.  I think
> it would be silly to incorporate the wackamole "technology" into your
> app.

I think there is something fundamental one of us is missing. I need my app to
force wackamole to allocate the single ip to the 'active master'. If I run
the wackamole app without removing the wackamole group join then I have no
way of influencing wackamole other than killing the local wackamole process

If I remove the join in wackamole and instead have ONLY the active master
join the wackamole group in my app then I can force the ip to point to active

How would I do the following with wackamole running as a separate entity;
Wackamole bases ip address allocation changes on wackamole group joins and
exits. I can see no way of triggering this ....

>it can
> always trigger wackamole to give up it's IP address to another master.

David T


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