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

Theo Schlossnagle jesus at omniti.com
Fri May 3 07:57:58 EDT 2002

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 

Theo Schlossnagle
Principal Consultant
OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
Phone:  +1 301 776 6376       Fax:  +1 410 880 4879
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