[Linux-cluster] RFC: Configuration of Red Hat clusters in Cluster 3

[Steven Whitehouse]

Hi,

On Tue, 2009-10-27 at 11:07 +0000, Christine Caulfield wrote:
> Hi all,
> 
> I've been thinking about configuring clusters, particularly in a 
> virtualised environment. The solutions we have for this are not 
> especially good I don't think.
> 
> We currently have two loaders:
> 
> xmlconfig is the default and reads from /etc/cluster/cluster.conf (by 
> default)
> 
> ldapconfig reads from an LDAP server
> 
> Both of these have their uses of course. But, especially in a 
> virtualised environment, they are not particularly handy. LDAP is 
> cumbersome and complicated to configure and we have no real tools to 
> update it directly. Reading from local files seems a bit primitive in a 
> virtualised system where you have at least one host system that is 
> guaranteed to be available because it is actually running the guests 
> themselves.
> 
> Yes, we have ccs_sync that will synchronise the configuration across 
> nodes, and that is integrated into 'cman_tool version' now, but it still 
> seems cumbersome to me and doesn't work properly if a cluster node is 
> down when the configuration is changed.
> 
> What I think would be nice would be to update the configuration on a 
> host node (dom0 in Xen parlance) and have the other nodes automatically 
> pick it up from that one place.
> 
> One suggested way of doing this is to host the cluster.conf file on an 
> HTTP server on the host. The VMs can then simply GET that file and run 
> it through xmlconfig to load it into corosync. This seems simple and 
> easy to me. Most people know how to set up an http server (even if they 
> don't know how to secure one!)
> 
> The intention is to make this as easy as possible, so that the admin 
> staff simply supply a URL and corosync does the right thing to fetch it 
> when needed (at boot up and re-configure time). This magic is brought to 
> you courtesy of pluggable configuration modules in corosync :)
> 
> Comments? Better ideas? Or am I just barking ?
> 
> 
That sounds like a good idea to me. Better still if it can be extended
in the future to pull other bits of config too,

Steve.