[Spread-users] Dynamic configuration

[John Lane Schultz]

Nolan Johnson wrote:
> John Schultz said:
> 
>> During a run, a Spread daemon cannot tolerate its IP 
>> address changing.  If the daemon's IP address changes, 
>> then the daemon will have to be shut down and you will 
>> have to dynamically change the  configuration of the 
>> system to change the IP address of that daemon.
> 
> Can you elaborate on what you mean by "dynamically change the configuration"?
> 
> From what I can see from the documentation (did I miss something?), the IPs of all of the nodes in the group need to be in the config of every daemon.  Is there some way that a new daemon can automatically add itself to a group without changing configs?
> 
> I'm interested in this from a different angle than the original poster - I'd like to add new daemons at will, non-disruptively.
> 
> Thanks.
> 

Spread 4 added the ability to dynamically add/remove daemons or to change other 
configuration options (e.g. - IP addresses, segment addresses, etc.) without 
shutting down the whole system.

It is still true that all daemons must be working from the same configuration 
file and it must contain all daemons.  However, you can instruct a Spread 4 
daemon to re-load its (changed) configuration file from disk.

So, if you want to add a new daemon -- run spmonitor using the old config file, 
add the appropriate entries for the new daemon to the file, distribute the new 
configuration file to all the daemons' machines and then through spmonitor 
instruct all the daemons to re-load their configuration file.

Depending on the types of changes you make the system may continue on 
uninterrupted, it may go through a membership change and/or several of the 
daemons may commit suicide (in order to restart).

See the DynamicConfiguration.txt file in the docs directory for a full run down.

Cheers!

-- 
John Schultz
Spread Concepts LLC
Phn: 443 838 2200
Fax: 301 560 8875