Re: [Libvir] Persistent Configurations?

Daniel Veillard wrote: > Yeah my first reaction was to provide XML based configuration files >that libvir would be able to understand, but I really think the >configurations >may come from very varied sources possibly databases. That's why I would >rather have the library agnostic when it comes to what a configuration >may look like. > > I'll have to think about this one. My biggest fear is that if there are a bunch of management tools capable of creating domains you'll end up with a bunch of different places storing configs.

> What is needed to start a domain ? > Required 1) name of domain 2) initial memory 3) maximum memory Optional 4) uuid 5) ssidref 6) poweroff, reboot, crash actions 7) number of vcpus 8) initial vcpu => cpu mapping Builder Specific Info Linux (misnomer, this is really any PV domain) Required 1) kernel Optional 2) ramdisk 3) root device 4) extra (additional kernel args) Vmx (another misnomer, really any FV domain) Required 1) device model path Optional 2) device model arguments 3) DISPLAY Device Specific Info VBD 1) backend ID 2) uname (file:/path/to/file) 3) dev (hda1) 4) mode (r, w, w!) VIF Required 1) backend ID 2) MAC Optional 3) bridge 4) ip 5) script 6) vifname PIO Range 1) starting address 2) enabling address Of course, this is subject to change as new features are added but I'm pretty sure this is pretty complete.

>For Xen we know what is needed, at >least at the moment (paths to kernels, images, block devices paths, network >devices and I/Os), but this may change slightly with full virtualization, >and other virtualization engine like QEmu have different ways since they >emulate the bootstrap process too. > > Fortunately, since FV uses the qemu device model, we could launch qemu pretty easily reusing this existing config format (since qemu already is launched anyway). However, IMHO, the VBD description Xen uses sucks so I'm not sure we want to adopt it as the universal model. > To me we don't have a good answer to this question so that's one more > reason >to keep this as opaque as possible. > > opaqueness means easy backwards and forward compatibility so I'm definitely a fan :-)

I definitely think it might be worthwhile to design a Xen configuration schema that we could keep consistent as things move forward. Some things would obviously map 1-1 like name but other things might require careful thinking (like block devices). Thoughts?