Re: [PATCH 02/11] hyperv: implement domainUndefine and domainUndefineFlags
On Nov 26, 2020, at 9:26 AM, Daniel P. Berrangé
<berrange(a)redhat.com> wrote:
On Tue, Nov 24, 2020 at 02:48:31PM -0500, Matt Coleman wrote:
> + /* try to shut down the VM if it's not disabled, just to be safe */
> + if (computerSystem->data->EnabledState !=
MSVM_COMPUTERSYSTEM_ENABLEDSTATE_DISABLED &&
> + hypervDomainShutdown(domain) < 0) {
> + goto cleanup;
> + }
Many, but not all, drivers in libvirt allow undefining the cofig for a running
VM. ie we can delete the config on disk, without affecting the running VM.
This results in a so called "transient" VM - basically a VM which only exists
as long as it is running - virDomainCreateXML creates such a beast, while
virDomainDefineXML+virDomainCreate creates a "persistent" VM and starts it.
If hyperv doesn't allow that, then shutting down the VM is likely to be
surprising.
I'd suggest we report an error indicating undefine is not permitted for a
running VM in such a case.
Hyper-V does not allow a VM's definition to be deleted if it's active,
paused, or in state transition.
If I remove the check entirely, it displays an error including
Hyper-V's method name, the error code from Hyper-V, and a string that's
generated by hypervReturnCodeToString() from hyperv_wmi.c.
For example, `virsh undefine runningvm` would throw the error:
error: Failed to undefine domain runningvm
error: internal error: Invocation of DestroySystem returned an error: Invalid state for
this operation (32775)
That simplifies the code significantly and provides details (the method
name and error code) that users could look up in Microsoft's
documentation. However, I don't think it's very clearly phrased.
"Domain must not be active or in state transition" with the error code
set to VIR_ERR_OPERATION_INVALID produces the following error output:
error: Failed to undefine domain testvm
error: Requested operation is not valid: Domain must not be active or in state transition
It's a difference of 18 lines (51 vs 33). The shorter version
eliminates the result and computerSystem variables, does not use goto,
and only sends a single WMI request to Hyper-V since it does not have
to query the VM state before attempting to undefine it.
Would you prefer to have simpler code or a custom error message?
Thanks!
Matt