On Tue, 14 Sep 2021 17:16:11 +0200
Peter Krempa <pkrempa@xxxxxxxxxx> wrote:
> Issuing simple QMP commands is pain as they need to be wrapped by the
> JSON wrapper:
>
> { "execute": "COMMAND" }
>
> and optionally also:
>
> { "execute": "COMMAND", "arguments":...}
>
> For simple commands without arguments we can add syntax sugar to virsh
> which allows simple usage of QMP and additionally prepares also for
> passing through of the 'arguments' section:
>
> virsh qemu-monitor-command --qmpwrap $VM query-status
>
> is equivalent to
>
> virsh qemu-monitor-command $VM '{"execute":"query-status"}'
>
> and
>
> virsh qemu-monitor-command --qmpwrap $VM query-named-block-nodes
> '{"flat":true}'
>
> is equivalent to
>
> virsh qemu-monitor-command $VM
> '{"execute":"query-named-block-nodes", "arguments":{"flat":true}}'
>
> Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
> ---
>
> I originally called the flag '--qmp' but that could be confusing given
> that we have '--hmp'. On the other hand it's shorter so I wouldn't
> mind turning it back to '--qmp'.
I like the idea, as I also find the qemu-monitor-command to be
awkward to use. I'm not crazy about the name --qmpwrap, though. I
kind of wish we could do something like
virsh qemu-monitor-command --cmd command-name --args '{"arg1":true}'
but --cmd is already taken as an optional flag for the full
json-formatted command. I'm not sure I have any better ideas though.
Tangent: Reading the code for this function leads me the surprising
discovery that these two commands are actually identical:
qemu-monitor-command vm --cmd {\"execute\": \"help\"}
qemu-monitor-command vm {\"execute\": --cmd \"help\"}
Jonathon
>
> docs/manpages/virsh.rst | 9 ++++++++-
> tools/virsh-domain.c | 31 ++++++++++++++++++++++++++++---
> 2 files changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
> index 9561b3f59d..b8cb3cfbc2 100644
> --- a/docs/manpages/virsh.rst
> +++ b/docs/manpages/virsh.rst
> @@ -7694,7 +7694,8 @@ qemu-monitor-command
>
> ::
>
> - qemu-monitor-command domain { [--hmp] | [--pretty]
> [--return-value] } command...
> + qemu-monitor-command domain { [--hmp] | [--qmpwrap] [--pretty]
> + [--return-value] } command...
>
> Send an arbitrary monitor command *command* to domain *domain*
> through the QEMU monitor. The results of the command will be printed
> on stdout. @@ -7705,6 +7706,12 @@ a space in between before passing
> the single command to the monitor. Note that libvirt uses the QMP to
> talk to qemu so *command* must be valid JSON in QMP format to work
> properly.
>
> +If *--qmpwrap* is passed the first argument passed as *command* is
> used as a QMP +command name and appropriately wrapped into a JSON
> block. Additionally a second +argument passed as *command* is
> appended as value of the 'arguments' parameter +of the QMP command
> verbatim. *Note* that in the future automatic formatting +*--qmpwrap*
> of the arguments might be added, so scripts should format their own
> JSON. + If *--pretty* is given the QMP reply is pretty-printed.
>
> If *--return-value* is given the 'return' key of the QMP response
> object is diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
> index e5bd1fdd75..ac57196b20 100644
> --- a/tools/virsh-domain.c
> +++ b/tools/virsh-domain.c
> @@ -9380,6 +9380,10 @@ static const vshCmdOptDef
> opts_qemu_monitor_command[] = { .type = VSH_OT_BOOL,
> .help = N_("extract the value of the 'return' key from the
> returned string") },
> + {.name = "qmpwrap",
> + .type = VSH_OT_BOOL,
> + .help = N_("wrap the 'cmd' argument in JSON wrapper for QMP")
> + },
> {.name = "cmd",
> .type = VSH_OT_ARGV,
> .flags = VSH_OFLAG_REQ,
> @@ -9405,14 +9409,35 @@ cmdQemuMonitorCommand(vshControl *ctl, const
> vshCmd *cmd)
>
> VSH_EXCLUSIVE_OPTIONS("hmp", "pretty");
> VSH_EXCLUSIVE_OPTIONS("hmp", "return-value");
> + VSH_EXCLUSIVE_OPTIONS("hmp", "qmpwrap");
>
> if (!(dom = virshCommandOptDomain(ctl, cmd, NULL)))
> return false;
>
> - while ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> - virBufferAsprintf(&buf, "%s ", opt->data);
> + if (vshCommandOptBool(cmd, "qmpwrap")) {
> + const char *command = NULL;
> + const char *arguments = NULL;
>
> - virBufferTrim(&buf, " ");
> + if ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> + command = opt->data;
> + if ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> + arguments = opt->data;
> +
> + if (!command || (arguments && vshCommandOptArgv(ctl, cmd,
> opt))) {
> + vshError(ctl, "%s", _("--qmpwrap option requires 1 or 2
> arguments"));
> + return false;
> + }
> +
> + virBufferAsprintf(&buf, "{\"execute\":\"%s\"", command);
> + if (arguments)
> + virBufferAsprintf(&buf, ", \"arguments\":%s", arguments);
> + virBufferAddLit(&buf, "}");
> + } else {
> + while ((opt = vshCommandOptArgv(ctl, cmd, opt)))
> + virBufferAsprintf(&buf, "%s ", opt->data);
> +
> + virBufferTrim(&buf, " ");
> + }
>
> monitor_cmd = virBufferContentAndReset(&buf);
>
