[virt-tools-list] [libvirt] question about syntax of storage volume <target> element
Cole Robinson
crobinso at redhat.com
Fri Oct 5 22:00:45 UTC 2018
On 10/05/2018 05:41 PM, Jim Fehlig wrote:
> On 10/5/18 3:27 PM, Cole Robinson wrote:
>> On 10/02/2018 01:09 PM, Jim Fehlig wrote:
>>> On 10/2/18 9:27 AM, Cole Robinson wrote:
>>>> On 10/02/2018 10:53 AM, Jim Fehlig wrote:
>>>>> On 10/2/18 5:13 AM, Pavel Hrdina wrote:
>>>>>> On Mon, Oct 01, 2018 at 02:28:09PM -0400, Cole Robinson wrote:
>>>>>>> On 09/28/2018 12:54 AM, Jim Fehlig wrote:
>>>>>>>> I've attempted to use virt-manager to create a new VM that uses
>>>>>>>> a volume
>>>>>>>> from an rbd-based network pool, but have not been able to
>>>>>>>> progress past
>>>>>>>> step 4/5 where VM storage is selected. It appears virt-manager has
>>>>>>>> problems properly detecting the volume as network-based storage,
>>>>>>>> but
>>>>>>>> before investigating those further I have a question about the
>>>>>>>> syntax of
>>>>>>>> the <target> element of a storage volume.
>>>>>>>
>>>>>>> Yeah virt-manager is known to be lacking WRT rbd. I did some work
>>>>>>> a few
>>>>>>> years back but didn't finish it. At least it doesn't know how to
>>>>>>> correctly
>>>>>>> use a volume with any auth data in the XML. I need to get another
>>>>>>> rbd setup
>>>>>>> to test with and fix it all
>>>>>>
>>>>>> I was investigating the RBD support as well and in order to add
>>>>>> proper
>>>>>> support for it into virt-manager we need to add support for secrets.
>>>>>
>>>>> Right. But I was starting with the assumption that a "storage
>>>>> admin" setup an rbd-based pool, necessary secrets, etc. Then user
>>>>> creating a new VM could select existing volumes in the pool or
>>>>> create new ones at step 4/5 of the VM creation wizard. Currently a
>>>>> user can select an existing volume or create a new one, but can't
>>>>> progress beyond that point. I have a hack (attached, based against
>>>>> 1.5.1) to workaround the problem in virt-manager. Commit 582c1d3d
>>>>> fixed virt-install to copy auth data from the pool to the device
>>>>> config in domXML and as a first step I'm trying to do the same with
>>>>> virt-manager.
>>>>>
>>>>
>>>> dropping libvir-list and adding virt-tools-list
>>>>
>>>> Cool, thanks for working on this. Can you provide:
>>>>
>>>> - pool XML you are using
>>>
>>> <pool type="rbd">
>>> <name>rbdpool</name>
>>> <source>
>>> <name>libvirt-pool</name>
>>> <host name='foo.bar.com' port='6789'/>
>>> <auth username='libvirt' type='ceph'>
>>> <secret uuid='c451d49d-a48b-43d8-bd78-97ccebd7d67a'/>
>>> </auth>
>>> </source>
>>> </pool>
>>>
>>>> - vol XML
>>>
>>> <volume type='network'>
>>> <name>test-image</name>
>>> <key>libvirt-pool/test-image</key>
>>> <source>
>>> </source>
>>> <capacity unit='bytes'>21474836480</capacity>
>>> <allocation unit='bytes'>5481955328</allocation>
>>> <target>
>>> <path>libvirt-pool/test-image</path>
>>> <format type='raw'/>
>>> </target>
>>> </volume>
>>>
>>>> - the backtrace you are hitting
>>>
>>> The first hunk in diskbackend.py of my hack fixes this backtrace
>>> (including a bit of preceding context)
>>>
>>> [Tue, 02 Oct 2018 10:53:41 virt-manager 20533] DEBUG
>>> (storagebrowse:53) Showing storage browser
>>> [Tue, 02 Oct 2018 10:53:57 virt-manager 20533] DEBUG
>>> (storagebrowse:138) Chosen volume XML:
>>> <volume type="network">
>>> <name>test-image</name>
>>> <key>libvirt-pool/test-image</key>
>>> <source>
>>> </source>
>>> <capacity unit="bytes">21474836480</capacity>
>>> <allocation unit="bytes">5481955328</allocation>
>>> <target>
>>> <path>libvirt-pool/test-image</path>
>>> <format type="raw"/>
>>> </target>
>>> </volume>
>>> [Tue, 02 Oct 2018 10:53:57 virt-manager 20533] DEBUG
>>> (storagebrowse:66) Closing storage browser
>>> [Tue, 02 Oct 2018 10:54:04 virt-manager 20533] DEBUG
>>> (diskbackend:170) Attempting to build pool=libvirt-pool
>>> target=/usr/share/virt-manager/virtinst/libvirt-pool
>>> [Tue, 02 Oct 2018 10:54:04 virt-manager 20533] DEBUG (storage:524)
>>> Creating storage pool 'libvirt-pool' with xml:
>>> <pool type="dir">
>>> <name>libvirt-pool</name>
>>> <target>
>>> <path>/usr/share/virt-manager/virtinst/libvirt-pool</path>
>>> </target>
>>> </pool>
>>> [Tue, 02 Oct 2018 10:54:04 virt-manager 20533] ERROR (error:143)
>>> Validation Error: Storage parameter error. Could not start storage
>>> pool: cannot open directory
>>> '/usr/share/virt-manager/virtinst/libvirt-pool': No such file or
>>> directory
>>> Traceback (most recent call last):
>>> File "/usr/share/virt-manager/virtManager/create.py", line 2305,
>>> in _validate_storage_page
>>> path=path)
>>> File "/usr/share/virt-manager/virtManager/addstorage.py", line
>>> 262, in validate_storage
>>> disk.path = path or None
>>> File "/usr/share/virt-manager/virtinst/devicedisk.py", line 519,
>>> in _set_path
>>> (vol_object, parent_pool) = diskbackend.manage_path(self.conn,
>>> newpath)
>>> File "/usr/share/virt-manager/virtinst/diskbackend.py", line 176,
>>> in manage_path
>>> pool = poolxml.install(build=False, create=True, autostart=True)
>>> File "/usr/share/virt-manager/virtinst/storage.py", line 559, in
>>> install
>>> raise RuntimeError(errmsg)
>>> RuntimeError: Could not start storage pool: cannot open directory
>>> '/usr/share/virt-manager/virtinst/libvirt-pool': No such file or
>>> directory
>>>
>>> After fixing the above I see errors trying to change the permissions
>>> on the volume
>>>
>>> [Tue, 02 Oct 2018 10:58:35 virt-manager 20822] DEBUG (addstorage:143)
>>> No search access for dirs: ['libvirt-pool', '']
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (addstorage:156)
>>> Attempting to correct permission issues.
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (devicedisk:290)
>>> Ran command '['setfacl', '--modify', 'user:qemu:x', '']'
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (devicedisk:292)
>>> out=b''
>>> err=b'setfacl: : No such file or directory\n'
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (devicedisk:325)
>>> setfacl failed, trying old fashioned way
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (devicedisk:297)
>>> Setting +x on
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (devicedisk:297)
>>> Setting +x on libvirt-pool
>>> [Tue, 02 Oct 2018 10:59:46 virt-manager 20822] DEBUG (addstorage:171)
>>> Permission errors:
>>> : [Errno 2] No such file or directory: ''
>>> libvirt-pool : [Errno 2] No such file or directory: 'libvirt-pool'
>>> It is very likely the VM will fail to start up.
>>>
>>> The hunk in devicedisk.py fixes this by skipping the permissions
>>> check for network-based volumes.
>>>
>>>> Maybe I can distill that stuff into something that's easy to
>>>> reproduce with the testdriver
>>>
>>
>> Ahh now that I look at the diffs, they are both in sections of the
>> code that only run or fail in real scenarios: manage_storage will
>> always succeed with the testdriver, and generally the path perms
>> checking isn't run in the test suite. I can probably hack up some unit
>> tests to demonstrate the fixes though.
>>
>> But yeah as you've seen this boils down to virtinst having the wrong
>> assumption that a network volume <path> is easily identifiable as a
>> URL, which while it works for gluster doesn't work for rbd/sheepdog.
>>
>> I'll help with unittests when the patches are ready for posting
>
> I'm not really sure what else to do with the patch, other than remove
> the lame debugging lines. It's a small improvement that fixes use case
> of selecting an existing volume (or creating a new one) from an existing
> network pool when creating a new VM.
>
> Were you looking for a more complete rbd solution where virt-manager
> supports creating rbd pools, secrets, etc. as Pavel suggested?
Oh, it sounded like you had more work coming so I was just gonna wait
for it to be posted. If they are done then please rebase and git
format-patch them
Thanks,
Cole
- Cole
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