83c6d80abc
Libvirt provides QMP passthrough APIs for the QEMU driver and these are
exposed in virsh. It is not especially pleasant, however, using the raw
QMP JSON syntax. QEMU has a tool 'qmp-shell' which can speak QMP and
exposes a human friendly interactive shell. It is not possible to use
this with libvirt managed guest, however, since only one client can
attach to the QMP socket at any point in time. While it would be
possible to configure a second QMP socket for a VM, it may not be
an known requirement at the time the guest is provisioned.
The virt-qmp-proxy tool aims to solve this problem. It opens a UNIX
socket and listens for incoming client connections, speaking QMP on
the connected socket. It will forward any QMP commands received onto
the running libvirt QEMU guest, and forward any replies back to the
QMP client. It will also forward back events.
$ virsh start demo
$ virt-qmp-proxy demo demo.qmp &
$ qmp-shell demo.qmp
Welcome to the QMP low-level shell!
Connected to QEMU 6.2.0
(QEMU) query-kvm
{
"return": {
"enabled": true,
"present": true
}
}
Note this tool of course has the same risks as the raw libvirt
QMP passthrough. It is safe to run query commands to fetch information
but commands which change the QEMU state risk disrupting libvirt's
management of QEMU, potentially resulting in data loss/corruption in
the worst case. Any use of this tool will cause the guest to be marked
as tainted as an warning that it could be in an unexpected state.
Since this tool introduces a python dependency it is not desirable
to include it in any of the existing RPMs in libvirt. This tool is
also QEMU specific, so isn't appropriate to bundle with the generic
tools. Thus a new RPM is introduced 'libvirt-clients-qemu', to
contain additional QEMU specific tools, with extra external deps.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2.8 KiB
virt-qemu-qmp-proxy
Expose a QMP proxy server for a libvirt QEMU guest
- Manual section
1
- Manual group
Virtualization Support
SYNOPSIS
virt-qemu-qmp-proxy [OPTION]... DOMAIN QMP-SOCKET-PATH
DESCRIPTION
This tool provides a way to expose a QMP proxy server that communicates with a QEMU guest managed by libvirt. This enables standard QMP client tools to interact with libvirt managed guests.
NOTE: use of this tool will result in the running QEMU guest being marked as tainted. It is strongly recommended that this tool only be used to send commands which query information about the running guest. If this tool is used to make changes to the state of the guest, this may have negative interactions with the QEMU driver, resulting in an inability to manage the guest operation thereafter, and in the worst case potentially lead to data loss or corruption.
The virt-qemu-qmp-proxy program will listen on a UNIX socket for incoming client connections, and run the QMP protocol over the connection. Any commands received will be sent to the running libvirt guest, and replies sent back.
The virt-qemu-qmp-proxy program may be interrupted (eg Ctrl-C) when it is no longer required. The libvirt QEMU guest will continue running.
OPTIONS
DOMAIN
The ID or UUID or Name of the libvirt QEMU guest.
QMP-SOCKET-PATH
The filesystem path at which to run the QMP server, listening for incoming connections.
-c CONNECTION-URI --connect=CONNECTION-URI
The URI for the connection to the libvirt QEMU driver. If omitted, a URI will be auto-detected.
-v, --verbose
Run in verbose mode, printing all QMP commands and replies that are handled.
-h, --help
Display the command line help.
EXIT STATUS
Upon successful shutdown, an exit status of 0 will be set. Upon failure a non-zero status will be set.
AUTHOR
Daniel P. Berrangé
BUGS
Please report all bugs you discover. This should be done via either:
the mailing list
the bug tracker
Alternatively, you may report bugs to your software distributor / vendor.
COPYRIGHT
Copyright (C) 2022 by Red Hat, Inc.
LICENSE
virt-qemu-qmp-proxy is distributed under the terms of the GNU LGPL v2+. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
SEE ALSO
virsh(1), https://libvirt.org/, QMP reference