Re: [Condor-users] condor on dhcp environment

[Joe Meehean <jmeehean@xxxxxxxxxxx>]

You may not need to edit /etc/hosts.  In the 
project Matt is referring to we simply set an 
environment variable to point to the currently 
assigned IP address of the machine.

Ex:
 _CONDOR_NETWORK_INTERFACE="172.16.241.130"

This only needs to be in the environment of the 
process that executes the condor_master.  If you 
can assume that IP addresses only change at reboot 
you can write a simple wrapper script around the 
condor_master that queries for the new IP address, 
sets this variable, then execs the master.

If on the other hand, there is a hard-limit on the 
lease time for IP addresses your task becomes more 
difficult because you must handle IP address 
changes while condor is running.  This requires 
detecting the change, reseting the env variable, 
and restarting condor.

Allowing the CM to have a dynamically assigned IP 
is even more difficult.  Other nodes must be able 
to find the CM, this requires DNS with low latency 
or Howl(AutoConf).  Additionally, other nodes must 
be able to detect an IP address change for the CM 
and restart.  If you aren't using DNS, the env 
variable _CONDOR_COLLECTOR_HOST must be set to the 
new IP address using dashes instead of dots.  And 
the config file must specify that you aren't using 
DNS.

Ex:
(In the env)
_CONDOR_COLLECTOR_HOST="172-16-241-130"
(In the config)
NO_DNS="TRUE"

Not a simple task.  And there is some inherent 
latency, since non-CM nodes must poll (using a 
cron script possible) every X amount of time to 
determine whether the CM's address has changed.

_joe


Matthew Farrellee wrote:
> A group of students here (myself included) did some experimenting  
> with an environment similar to yours in the spring. I seem to  
> remember we concluded that when the IP of your CM changes you should  
> restart the daemons on your execute nodes so you are sure that the IP  
> change is noticed. That should be as easy as your script updating / 
> etc/hosts and then firing off a "condor_off -master && sleep a bit &&  
> condor_master"
>
> Best,
>
>
> matt
>
> On Aug 14, 2006, at 5:09 AM, Nano Surbakti wrote:
>
> > Hi,
> >
> > I want to setup condor in a pool of computers that always change it's
> > IP everytime it reboot.
> > I can have one computer have a dynamic IP, which will be used as a
> > central manager.
> > I'm thinking of making a program on master and execute hosts, that
> > will update /etc/hosts file each time the IP changed. Is it possible
> > for Condor to work in such situation?
> >
> > What if there's no static IP at all (I can't even have the CM a  
> > static IP)?
> >
> > Regards,
> > --
> > Nano Surbakti
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