On Thu, Jun 13, 2019 at 03:17:16PM +0530, Varsha Verma wrote:
Hello everyone, I am doing an outreachy internship at Openstack Ironic. In the sushy-tools project, we are using libvirt VMs to simulate bare metal machines for testing purposes. In the XML description of a domain, there are a bunch of disk elements giving information about the various storage devices attached to the domain. Is there some way to get the size/capacity of those disks using the libvirt API?
Yes, there is, virStorageVolGetXMLDesc: https://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolGetXMLDesc Look for <capacity/> The tricky part might be to get the storage volume object. I'm not sure how sushy-tools are using libvirt and what the deployment looks like, so here are few tips and feel free to ask for more info. If it is a path on the local filesystem, you might just use `virStorageVolLookupByKey` and be done with it: https://libvirt.org/html/libvirt-libvirt-storage.html#virStorageVolLookupByKey If it is not, you might need to look it up based on the pool it is in. If you have the pool already, then it is a matter of `virStorageVolLookupBy*` for example. If you don't have that you might look for the pool with `virStoragePoolLookupBy*`, for example `virStoragePoolLookupByName`: https://libvirt.org/html/libvirt-libvirt-storage.html#virStoragePoolLookupByName And one more general libvirt advice (although maybe not really a good one, definitely not a silver bullet): You can always have a look at how `virsh` does things. It might be a bit confusing at times, but if you have a command name (in our case we'd use the `vol-dumpxml` command), you can CamelCase it ("VolDumpXML"), prepend "cmd" (as in "command") and the resulting name (`cmdVolDumpXML`) is the name of the function that virsh runs for that command. You can see it in tools/virsh-volume.c: https://github.com/libvirt/libvirt/blob/master/tools/virsh-volume.c#L1211 The main part of how it looks up a volume is `virshCommandOptVol` which is just a syntax sugar for `virshCommandOptVolBy` in the same file: https://github.com/libvirt/libvirt/blob/master/tools/virsh-volume.c#L68 Which is trying to do the lookup by all various possible things. Same thing can be found for `pool-*` commands. HTH, have a nice day, Martin
-- *Regards,* *Varsha Verma* *Fourth Year Undergraduate* *Department of Electrical Engineering* *IIT-BHU, Varanasi*
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