On 23.08.2016 13:03, Christian Loehle wrote:
> I'm trying to use virt-manager with a custom libvirt hypervisor driver.
Wow, custom hypervisor driver? Sounds interesting - for what hypervisor
it is?
> My current problem is that virt-manager closes the connection because
> virNodeGetInfo(the python binding) returns None:
> Traceback (most recent call last):
> File
> "/home/cloehle/Documents/libvirt/virt-manager/virtManager/connection.py",
> line 1390, in tick_from_engine
> self._tick(*args, **kwargs)
> File
> "/home/cloehle/Documents/libvirt/virt-manager/virtManager/connection.py",
> line 1280, in _tick
> self._hostinfo = self._backend.getInfo()
> File "/usr/lib/python2.7/dist-packages/libvirt.py", line 3612, in getInfo
> if ret is None: raise libvirtError ('virNodeGetInfo() failed', conn=self)
> libvirtError: internal error: client socket is closed
>
> The virNodeGetInfo function of my driver should set a valid virNodeInfoPtr,
> since it only consists of the line:
> return nodeGetInfo(NULL, info);
Ah, this is the problem. You may want to look how other drivers do this.
For instance, qemu driver defines its own implementation:
.nodeGetInfo = qemuNodeGetInfo, /* 0.2.0 */
static int
qemuNodeGetInfo(virConnectPtr conn,
virNodeInfoPtr nodeinfo)
{
if (virNodeGetInfoEnsureACL(conn) < 0)
return -1;
return nodeGetInfo(nodeinfo);
}
> virsh shows no problems which is why I suspect this is a problem with
> libvirt-python.
This looks suspicious, are you sure you have the correct connection URI
in virsh?
> So I looked at the source and the first thing that I noticed is in line 2753
> of libvirt-override.c:
> if (!PyArg_ParseTuple(args, (char *)"O:virDomainGetInfo", &pyobj_conn))
> return NULL;
>
> Since this is for virNodeGetInfo this should probably be virNodeGetInfo
> instead of domain(the same thing occurs in line 2794 for another function).
Yeah, nice catch! But those are just prefixes for some error messages
[1]. Nevertheless, I've posted a fix for that [2].
> This could be my source of error but doesn't have to be. Could someone walk
> me through finding the reason why libvirt-python returns None for my
> virNodeGetInfo?
One possibility might be that you've passed invalid connection. It
should be possible to: a) see error in the daemon's log, b) set up
client logs to see whether error occurs there. [3].
> Is there any good way of debugging where exactly libvirt-python encounters an
> error and returns None?4
Yes, you should be able to just attach gdb to it and set a breakpoint.
After that you can just step through the function.
Michal
1: https://docs.python.org/3.5/c-api/arg.html
2: https://www.redhat.com/archives/libvir-list/2016-August/msg01089.html
3: http://wiki.libvirt.org/page/DebugLogs
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