Re: [Libguestfs] [v2v PATCH v2 1/4] output/create_libvirt_xml: wire up the QEMU guest agent

The intent (even before RHBZ#2028764) has been to install the QEMU guest agent in the converted domain unconditionally. Therefore, in order for the GA to be actually accessible from the host side, augment the libvirt output module with a "guest agent connection" also unconditionally. For starters, the domain needs a virtio-serial device. Then there must be a port on the device that (in the guest) the GA identifies by name, and that (on the host) is exposed as a listening socket (usually in the unix address family). The adress of that port (usually a pathname, i.e., for a unix domain socket) is then passed to whatever host-side application wants to talk to the GA. The minimal domain XML fragment for that ("minimal" for our purposes) is <controller type='virtio-serial' model='virtio'> <channel type='unix'> <target type='virtio' name='org.qemu.guest_agent.0'/> </channel> The "controller" element is needed because "controller/@model" is where we regulate "virtio" vs. "virtio-transitional". Everything else is filled in by libvirt. Notably, libvirt (a) creates and binds the unix domain socket itself (usually "/var/lib/libvirt/qemu/channel/target/DOMAIN/org.qemu.guest_agent.0"), (b) passes the file descriptor to QEMU, and (c) figures out the socket pathname for commands such as virsh domfsinfo DOMAIN virsh domhostname DOMAIN --source agent virsh domifaddr DOMAIN --source agent virsh guestinfo DOMAIN For QEMU, the corresponding options would be -chardev socket,id=agent,server=on,wait=off,path=/tmp/DOMAIN-agent \ -device virtio-serial-pci,id=vioserial \ -device virtserialport,bus=vioserial.0,nr=1,chardev=agent,name=org.qemu.guest_agent.0 \ Note the "path=/tmp/DOMAIN-agent" property of "-chardev"; virt-v2v would have to generate that (in place of the "fd=nnnn" property that libvirt passes to QEMU). Omit extending the QEMU output module for now, as the QGA protocol is based on JSON, and one needs "virsh" or "virt-manager" (or another management application interface) anyway, for efficiently exchanging messages with QGA. I don't know of end-user tools that directly connect to "/tmp/DOMAIN-agent". Don't modify the RHV and OpenStack outputs either; both of these management products likely configure the virtio-serial device automatically, for the agent access. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2028764 Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; --- Notes: v2: - no change output/create_libvirt_xml.ml | 11 +++++++++++ tests/test-v2v-i-ova.xml | 4 ++++ 2 files changed, 15 insertions(+) diff --git a/output/create_libvirt_xml.ml b/output/create_libvirt_xml.ml index 68d0a90918f3..531a4f75bf3e 100644 --- a/output/create_libvirt_xml.ml +++ b/output/create_libvirt_xml.ml @@ -524,6 +524,17 @@ let create_libvirt_xml ?pool source inspect e "console" ["type", "pty"] []; ]; + (* Given that we install the QEMU Guest Agent for both Linux and Windows + * guests unconditionally, create the virtio-serial device that's needed for + * communication between the host and the agent. + *) + List.push_back_list devices [ + e "controller" ["type", "virtio-serial"; "model", virtio_model] []; + e "channel" ["type", "unix"] [ + e "target" ["type", "virtio"; "name", "org.qemu.guest_agent.0"] [] + ] + ]; + List.push_back_list body [ e "devices" [] !devices; ]; diff --git a/tests/test-v2v-i-ova.xml b/tests/test-v2v-i-ova.xml index 6b8cda62f051..da1db473e53c 100644 --- a/tests/test-v2v-i-ova.xml +++ b/tests/test-v2v-i-ova.xml @@ -49,5 +49,9 @@ <input type='tablet' bus='usb'/> <input type='mouse' bus='ps2'/> <console type='pty'/> + <controller type='virtio-serial' model='virtio'/> + <channel type='unix'> + <target type='virtio' name='org.qemu.guest_agent.0'/> + </channel> </devices> </domain>