Hi Michal,
Thank you. Would you be so kind to provide me with additional clarification?
> you can’t just add a random tag into libvirt xml in a random place, it will
> be dropped by libvirt.
I understand, thank you. About persistence of added tag, it was not
used/written during 1xMigration, but it was present in domxml in 2xMigration.
> you can add it to metadata though. we use that for ovirt-specific information
Can you please provide some more HowTo/HowNotTo information?
Can we manipulate the tag in metadata section in each iteration?
I assume VM metadata shared/communicated between Hosts or read and provided to
Hosts by oVirt-Engine?
In short we are trying to achive:
- start migration
- ex: 10_create_tag inserts <is_migration/> tag into XML
metadata section <= maybe we can use before_vm_migration_source hook
- migration is finished and after_vm_destroy hooks comes to turn:
- ex: 20_nsupdate reads the metadata and:
- if tag <is_migrated/> exists, do not run dns
update, but remove the tag
- if tag <is_migrated/> does not exists, run dns
update and remove the tag
Kindly awaiting your reply.
Marko Vrgotic
On 03/10/2019, 12:27, "Michal Skrivanek" <[email protected]> wrote:
> On 2 Oct 2019, at 13:29, Vrgotic, Marko <[email protected]> wrote:
>
> Any ideas
>
> From: "Vrgotic, Marko" <[email protected]>
> Date: Friday, 27 September 2019 at 17:26
> To: "[email protected]" <[email protected]>
> Subject: How to pass parameters between VDSM Hooks domxml in single run
>
> Dear oVIrt,
>
> A while ago we discussed on ways to change/update content of parameters
of domxml in certain action.
>
> As I mentioned before, we have added the VDSMHook 60_nsupdate which
removes the DNS record entries when a VM is destroyed:
>
> …
> domxml = hooking.read_domxml()
> name = domxml.getElementsByTagName('name')[0]
> name = " ".join(name.nodeValue for name in name.childNodes if
name.nodeType == name.TEXT_NODE)
> nsupdate_commands = """server {server_ip}
> update delete {vm_name}.example.com a
> update delete {vm_name}. example.com aaaa
> update delete {vm_name}. example.com txt
> send
> """.format(server_ip="172.16.1.10", vm_name=name)
> …
>
> The goal:
> However, we did not want to execute remove dns records when VM is only
migrated. Since its considered a “destroy” action we took following approach.
> • In state “before_vm_migrate_source add hook which will write flag
“is_migration” to domxml
> • Once VM is scheduled for migration, this hook should add the flag
“is_migration” to domxml
> • Once 60_nsupdate is triggered, it will check for the flag and if
there, skip executing dns record action, but only remove the flag
“is_migration” from domxml of the VM
>
> …
> domxml = hooking.read_domxml()
> migration = domxml.createElement("is_migration")
> domxml.getElementsByTagName("domain")[0].appendChild(migration)
> logging.info("domxml_updated {}".format(domxml.toprettyxml()))
> hooking.write_domxml(domxml)
> …
>
> When executing first time, we observed that flag “
>
> <name>hookiesvm</name>
> <uuid>fcfa66cb-b251-43a3-8e2b-f33b3024a749</uuid>
> <metadata xmlns:ns0="http://ovirt.org/vm/tune/1.0";
xmlns:ns1="http://ovirt.org/vm/1.0";>
> <ns0:qos/>
> <ovirt-vm:vm xmlns:ovirt-vm="http://ovirt.org/vm/1.0";>
>
<ovirt-vm:clusterVersion>4.3</ovirt-vm:clusterVersion>
> <ovirt-vm:destroy_on_reboot
type="bool">False</ovirt-vm:destroy_on_reboot>
>
<ovirt-vm:launchPaused>false</ovirt-vm:launchPaused>
> <ovirt-vm:memGuaranteedSize
type="int">1024</ovirt-vm:memGuaranteedSize>
> <ovirt-vm:minGuaranteedMemoryMb
type="int">1024</ovirt-vm:minGuaranteedMemoryMb>
> ...skipping...
> <address bus="0x00" domain="0x0000"
function="0x0" slot="0x09" type="pci"/>
> </rng>
> </devices>
> <seclabel model="selinux" relabel="yes" type="dynamic">
> <label>system_u:system_r:svirt_t:s0:c169,c575</label>
>
<imagelabel>system_u:object_r:svirt_image_t:s0:c169,c575</imagelabel>
> </seclabel>
> <seclabel model="dac" relabel="yes" type="dynamic">
> <label>+107:+107</label>
> <imagelabel>+107:+107</imagelabel>
> </seclabel>
> <is_migration/>
you can’t just add a random tag into libvirt xml in a random place, it will
be dropped by libvirt.
you can add it to metadata though. we use that for ovirt-specific
information
> </domain>
> is added to domxml, but was present once 60_nsupdate hook was executed.
>
> The question: How do we make sure that, when domxml is updated, that the
update is visible/usable by following hook, in single run? How to pass these
changes between hooks?
>
> Kindly awaiting your reply.
>
>
> — — —
> Met vriendelijke groet / Kind regards,
>
> Marko Vrgotic
>
>
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