Status: Accepted
Owner: [email protected]
Labels: Type-Defect Milestone-Release2.9
New issue 691 by [email protected]: KVM path is not honoured
http://code.google.com/p/ganeti/issues/detail?id=691
This issue applies only to systems where /usr/bin/kvm does not exist.
Let's assume the KVM path is /usr/bin/qemu-kvm, as it is in Slackware 14.1.
In order for this Slackware KVM path to work, it is necessary to either
specify it as a configure option (which is not the case for this issue) or
use gnt-* modify. This issue focuses only on the latter.
At some point, when an instance is created, the KVM path is part of the
instance hvparams. This means that this argument must be passed around in
order for the kvm path to be properly used. However, the
method 'BaseHypervisor._InstanceStartupMemory', which takes the 'hvparams'
keyword argument, is not being properly called in several place in the code
(i.e., hvparams is not being passed), which means that KVM is not properly
invoked. Curiously enough, the issue happens with every second try of
starting a machine. Here is how to exercise the issue:
# gnt-instance add -n <node> -o <os> --no-install -H
kvm:boot_order=cdrom,cdrom_image_path=<image>-t file -s 1024m <inst>
This will create a stopped instance
# gnt-instance start <inst>
This will fail the first time. Here is the backtrace (notice the call to
_InstanceStartupMemory):
Traceback (most recent call last):
File "/usr/share/ganeti/2.10/ganeti/server/noded.py", line 181, in
HandleRequest
result = (True, method(serializer.LoadJson(req.request_body)))
File "/usr/share/ganeti/2.10/ganeti/server/noded.py", line 616, in
perspective_instance_start
return backend.StartInstance(instance, startup_paused, trail)
File "/usr/share/ganeti/2.10/ganeti/backend.py", line 1691, in
StartInstance
hyper.StartInstance(instance, block_devices, startup_paused)
File "/usr/share/ganeti/2.10/ganeti/hypervisor/hv_kvm.py", line 1979,
in StartInstance
self._ExecuteKVMRuntime(instance, kvm_runtime, kvmhelp)
File "/usr/share/ganeti/2.10/ganeti/hypervisor/hv_kvm.py", line 1959,
in _ExecuteKVMRuntime
start_memory = self._InstanceStartupMemory(instance)
File "/usr/share/ganeti/2.10/ganeti/hypervisor/hv_base.py", line 397,
in _InstanceStartupMemory
free_memory = self.GetNodeInfo(hvparams=hvparams)["memory_free"]
File "/usr/share/ganeti/2.10/ganeti/hypervisor/hv_kvm.py", line 2467,
in GetNodeInfo
_, v_major, v_min, v_rev = self._GetKVMVersion(kvmpath)
File "/usr/share/ganeti/2.10/ganeti/hypervisor/hv_kvm.py", line 2223,
in _GetKVMVersion
return cls._ParseKVMVersion(cls._GetKVMOutput(kvm_path,
cls._KVMOPT_HELP))
File "/usr/share/ganeti/2.10/ganeti/hypervisor/hv_kvm.py", line 2209,
in _GetKVMOutput
result = utils.RunCmd([kvm_path] + optlist)
File "/usr/share/ganeti/2.10/ganeti/utils/process.py", line 229, in
RunCmd
(strcmd, err))
OpExecError: Can't execute '/usr/bin/kvm --help': not found ([Errno 2] No
such file or directory)
# gnt-instance start <inst>
This will work the second time (I can't explain why).
The patch in attachment fixes this issue. However, it does not fix the
underlying problem. The following lines occur in 'KVMHypervisor.GetNodeInfo'
and 'KVMHypervisor.Verify':
kvmpath = constants.KVM_PATH
if hvparams is not None:
kvmpath = hvparams.get(constants.HV_KVM_PATH, constants.KVM_PATH)
These lines allow hvparams to be passed as None (or not passed at all
given that it is an optional argument to these functions) and, therefore,
allow the use of the configured KVM path, which is wrong. These functions
and calls to them should be revised and if possible the hvparams should
become a mandatory argument. This, however, is not in the patch.
Patch in the next comment.
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