On 01/28/2015 08:07 AM, Gabriel L. Somlo wrote: > Hi, > > I'm looking for an equivalent to VMWare "guestinfo" variables > (the stuff one may set on a VM via e.g. the vSphere client, under > Summary->Annotations->Notes, and looks like a bunch of "name = value" > environment variable definitions. These can then be retrieved from > the guest via 'vmtoolsd --cmd "info-get guestinfo.name"', which would > print the string "value" to stdout. > > After some initial digging, it appears that the QEMU guest agent is > the closest thing to "vmtoolsd" right now, but it doesn't look like > it supports the functionality I'm interested in. > > My question is, am I missing anything obvious? Is there anything in > the kvm/qemu/libvirt universe that currently offers this type of > functionality? If not, would it be of any interest? I'm willing (and > hopefully able) to send patches, if it comes to that :)
The existing qga allows you to write arbitrary contents from the host into an arbitrary file on the guest; you could use the contents of that file to be your name/value store or anything else. As for whether it makes sense to make it easier for the guests to access queries from such a file, I guess we could patch the qga package to provide such a helper app for use in the guest. Or if you want to add an entirely new guest-agent command that makes such contents easier for the host to pass than what you get by writing a raw file, you could try that as well. There are several example threads in the list archives of proposals to add new qga commands. > > Also, while extracting this type of "environment variable" on the > guest seems perfectly suited to something like qga, it also appears > that injecting them on the host side might involve cooperation from > a higher layer, such as libvirt. Yes, if you have a new qga command and/or new app bundled with qga used for querying a specific format of a specific file written by existing qga commands, then it would be reasonable to patch libvirt to make it easier to expose that functionality to the end user. But even without formal libvirt support, you can use the backdoor of 'virsh qemu-agent-command' to pass arbitrary qga commands through to the guest. > > Any pointers, ideas and tips much appreciated (even just "directions" > to a more appropriate mailing list)... > > Thanks much, > --Gabriel > > > -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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