Re: [libvirt] RFC: Add a 'reason' argument for domain events ?

One option is to add alot more events VIR_DOMAIN_MIGRATED_IN (migrated to another node) VIR_DOMAIN_MIGRATED_OUT (migrated from another node) VIR_DOMAIN_SHUTDOWN (graceful shutdown by host admin) VIR_DOMAIN_DESTROYED (force destroyed by host admin) VIR_DOMAIN_CRASHED (guest kernel crashed) VIR_DOMAIN_HUNG (host emulator hung) leaving STOPPED to just be a generic stop event, with no particular reason. The downside with this, is if an application just wants to know about whether a domain shutdown, not why, then they have to track lots and lots of events. Also, not every driver would be able to provide all of these events, so would often have to fallback on a generic STOPPED event

So one alternative is to provide a generic 'char * reason' with each event with provides scope on the cause of the lifecycle operation. So you'd get VIR_DOMAIN_STOPPED ("crashed", "shutdown", "destroyed", "quit", "hung", "migrated", "saved") VIR_DOMAIN_STARTED ("booted", "migrated", "restored") nb, we could remove the explicit SAVED and RESTORED events in this style. With such a 'reason' arg, we could possibly avoid adding the DEFINED and UNDEFINED events I suggested. Instead, adding a reason for ADDED and REMOVED events, VIR_DOMAIN_ADDED ("started", "defined") VIR_DOMAIN_REMOVED ("shutdown", "undefined") which lets you distinguish transient from persistent domains. The downside of this though, is that we can't explicitly track when a configuration file is 're-defined', eg adding a config file for an existing running guest.