[Users] oVirt Python SDK: getting the full filenames of disk images

[Dan Yasny]

Just make sure you are not changing anything that might cause a splitbrain
between the engine database and the actual image set on the storage, those
are usually tricky to debug and fix


On Thu, Dec 12, 2013 at 4:32 AM, Исаев Виталий Анатольевич <isaev at fintech.ru
> wrote:

>  Dan, thank you for a nice advice.  I have forgotten about domxml rich
> opportunities…
>
>
>
> Vitaly Isaev
>
> Software engineer
>
> Information security department
>
> Fintech JSC, Moscow, Russia
>
>
>
> *From:* Dan Yasny [mailto:dyasny at gmail.com]
> *Sent:* Monday, December 09, 2013 8:14 PM
>
> *To:* Исаев Виталий Анатольевич
> *Cc:* users at ovirt.org
> *Subject:* Re: [Users] oVirt Python SDK: getting the full filenames of
> disk images
>
>
>
> Please see reply inline
>
>
>
> On Mon, Dec 9, 2013 at 12:03 AM, Исаев Виталий Анатольевич <
> isaev at fintech.ru> wrote:
>
> Hi Dan, glad to meet you both on LOR and in this mailing list :)
>
>
>
> I know, I'm everywhere :)
>
>
>
>
>
> Unfortunately ovirtsdk.infrastructure.brokers.<anything> classes instances
> miss information about the higher objects very often. The typical situation
> is returning of empty string when we ask something about the parent from
> the child object ("child" and "parent" in terms Red Hat Enterprise
> Virtualization objects hierarchy). Consider this Python code:
>
>
>
>                 from ovirtsdk.api import API
>
>                 from ovirtsdk.xml import params
>
>                 ...
>
>                 api = API(...)
>
>                 d = api.vms.list()[i].get_disks().list()[i]
>                                                 #
> ovirtsdk.infrastructure.brokers.VMDisk class instance, i – any number in
> range(api.vms.list().__len__())
>
>                 s = d.get_storage_domains().get_storage_domain()[0]
>              # ovirtsdk.infrastructure.params.StorageDomain class instance
>
>                 t =
> s.get_data_center()
> # NoneType
>
>
>
> So you can see that this approach does not work here.
>
>
>
>
>
> I hope Michael or Itamar can shed some more light on this part, I don't
> have a system in front of me to check. AFAIR some objects aren't linked
> directly and you simply need to know how to get to them, I've had plenty of
> help from Michael before, when I was running a seemingly correct script,
> and getting no data, simply because I didn't understand the way the API
> looks for objects and relationships.
>
>
>
>  Our purpose is checking the VM’s disk image integrity (I mean integrity
> of system files, stored in /boot, /bin, /sbin, /lib etc.) every time the VM
> starts. The integrity checking script is written in Python and relies on
> libguestfs and vdsm hooks. Specific vdsm hook runs our script and block the
> VM’s boot process until the correctness of the system files hash sums will
> be checked. But libguestfs requires the full path to the disk to be
> handled, and it’s not integrated with ovirt infrastructure. And here we
> face with a task of full disk image filenames definition.
>
>
>
> I assume you are using before_vm_start? This will catch the VM
> definitions, as passed by the engine, and allow you to reassemble the
> domxml. You can get the disk path from the domxml directly, bypassing the
> engine APIs completely.
>
> The problem however, if you are doing this on block storage, is that the
> right LV will not be prepared for use by vdsm at this point, so you'll have
> to make it accessible manually, then disable access and let vdsm do it's
> job. Much easier with NFS/Gluster of course.
>
>
>
>
>
>
>
> Thank you,
>
> Vitaly Isaev
>
> Software engineer
>
> Information security department
>
> Fintech JSC, Moscow, Russia
>
>
>
> *From:* Dan Yasny [mailto:dyasny at gmail.com]
> *Sent:* Friday, December 06, 2013 8:56 PM
> *To:* Исаев Виталий Анатольевич
> *Cc:* users at ovirt.org
> *Subject:* Re: [Users] oVirt Python SDK: getting the full filenames of
> disk images
>
>
>
> Probably not, but you can
>
> - get the disk image UUID (that's the name in the filesystem or LV name),
>
> - get the UUID of the storage domain (that will be the top level dir name
> or VG name)
>
> - get the DC UUID (this will be the top level dir name and the mount point
> for LVM)
>
>
>
> Then compose the path out of these. Keep in mind that the disk UUID you
> get is the latest leaf in a snapshot tree, and if you need the entire chain
> of images, you need to recursively traverse the tree starting at the leaf,
> using the PUUID tag to find the parent.
>
>
>
> Might be a better way, but I'm not aware of it.
>
>
>
> Moreover, if you explain why you need to touch those images manually
> instead of letting ovirt handle everything, we might be able to suggest a
> better way
>
>
>
> --
>
> D
>
>
>
> On Wed, Dec 4, 2013 at 2:34 AM, Исаев Виталий Анатольевич <
> isaev at fintech.ru> wrote:
>
> Dear ovirt-engine users,
>
>
>
> I will be appreciated if someone experienced in oVirt Python SDK could
> advice the method of getting the full filename of the VM’s disk images in
> the RHEV hypervisor’s file system. Can I get filename with a full file
> system path from a ovirtsdk.infrastructure.brokers.VMDisk class instance?
>
>
>
> If Python SDK (what is preffered) can’t provide such an information, may
> be it is still possible with RHEV-M REST API?
>
>
>
> Thank you,
>
> Vitaly Isaev
>
> Software engineer
>
> Information security department
>
> Fintech JSC, Moscow, Russia
>
>
>
>
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