I seem to be living in constant fear of starting the same domain on more than one machine at once. As a way of preventing this, I''d like to be able to have a script execute as part of an ''xm create'' that runs before doing any of the actual domain creation. At the moment, all I''d do is do a ''ping'' to see if the domain is up and running. Not foolproof but would save me >99% of the time. In a cluster environment there should be a way to determine remotely if a domain is running. Ideally, there would be a ''dom_check_exists'' script automatically run (if it exists) which could be implemented in a cluster environment, but for now, where is a good place to hook into this? Thanks James _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Seems to me it might be nice to have a few hooks to trigger scripts at key points. You''d be able to configure these in the Xend config file (or similar) and use them to implement extra checks / logging / functionality for a specific environment.> Ideally, there would be a ''dom_check_exists'' script automatically run > (if it exists) which could be implemented in a cluster environment, but > for now, where is a good place to hook into this?Needs to go inside Xend to strictly fit into the architecture. How about hacking it into tools/python/xen/xend/XendDomainInfo.py::create()? Your first step would be to add a call to vm.precreate_trigger(), which would run your script in the first instance (or more generally, one that had been configured in Xend''s config). You could use the return value of the script to allow / disallow the creation, and return the output text as an error message. Of course, if you''re just interested in hacking something up quickly, you could add it to the xm tool''s create command. It''s a bit ugly but it''ll do the job and be quick to hack in. Cheers, Mark> Thanks > > James > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Fri, Jan 13, 2006 at 11:57:48AM +1100, James Harper wrote:> I seem to be living in constant fear of starting the same domain on more > than one machine at once. As a way of preventing this, I''d like to be > able to have a script execute as part of an ''xm create'' that runs before > doing any of the actual domain creation. > > At the moment, all I''d do is do a ''ping'' to see if the domain is up and > running. Not foolproof but would save me >99% of the time. In a cluster > environment there should be a way to determine remotely if a domain is > running.For such a quick-and-dirty check, couldn''t you just write yourself a wrapper script that did the ping and then called xm create? If you want to do this properly, then inside Xend would be the best place, as Mark Williamson suggests. XendRoot handles the config file and the script directories (see XendRoot.get_network_script for example). Cheers, Ewan. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel