Re: Guestinfo alike info polling from Guest via guest-agent

[Connor Kuehl]

On 11/21/24 5:33 AM, Florian Lohoff via wrote:
> 
> Hi,
> is there a way with qemu-guest-agent to push infos down to the
> hypervisor?

I may be placing undue emphasis on your use of the word "push", but
as far as I'm aware, qemu-guest-agent strictly responds to requests
*from* the hypervisor, and does not have a way of sending information
unsolicited to it.

> In VMWare one cat set guestinfo variables from within the guest which
> can then be retrieved from the Hypervisor. This enables a trusted way to
> pass on information for example ssh host keys which we use after
> installation.
> 
> We try to avoid connecting with -o stricthostkeychecking=no and
> insecurities alike. So having an off-channel method of retrieving
> ssh keys would be nice.

That said, the hypervisor can send requests to qemu-ga whenever it wants
(assuming the guest agent is listening.)

The qemu-ga protocol supports a number of remote procedure calls[1].
I recommend checking it out.

With regards to the specific use-case above, you might be able to accomplish
that with one or more of guest-file-open, guest-exec, or maybe
something else I didn't see.

[1] https://www.qemu.org/docs/master/interop/qemu-ga-ref.html

--
Connor