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h1. Cluster with libvirt

h2. Fontionnement

Les VM utilisent le mode ethernet de libvirt. En gros libvirt s'attends à trouver un tap tout près pour y accrocher la VM

Just avant le boot de la VM libvirt lance:

<pre> /etc/libvirt/hooks/qemu <VM_NAME> prepare begin</pre>

Et juste après l'arret de la VM libvirt lance:

<pre> /etc/libvirt/hooks/qemu <VM_NAME> release end</pre>

Le script /etc/libvirt/hooks/qemu de ttnn se trouve ici: https://chiliproject.tetaneutral.net/projects/git-tetaneutral-net/repository/puppetmaster/revisions/master/entry/environments/production/manifests/files/openstack/libvirt-hooks-qemu

Ce script va lire les metadatas TTNN de <VM_NAME> (e.g: virsh metadata <VM_NAME> http://tetaneutral.net/) 

<pre>

$ virsh metadata ns2.tetaneutral.net http://tetaneutral.net/

<config>

  <tap name="tapb0b4a106-d0">89.234.156.248</tap>

  <tap name="tapabababab-aa">89.234.156.45</tap>

</config>

</pre>

Ensuite il va créé le tap et configurer les routes dessus avec les infos des metadata.

h2. Migration from Openstack

* virsh dumpxml $id > myvm.xml

* delete VM in openstack

  on openstack.t server: 

  <pre>

  $ mysql nova -e "update instances set deleted=1 where display_name = 'ns2.tetaneutral.net';"

  </pre>

* edit myvm.xml

  * change name to <my_new_name>

  * remove uuid on top and uuid in sysinfo/system/entry[name=uuid]

  * change domain/devices/interface/@type == ethernet (instead of bridge)

  * remove <bridge ***>  in domain/devices/interface

  * On top in metadata add (tap names is located in domain/devices/interface/@type):

   <ttnn:config xmlns:ttnn="http://tetaneutral.net/">

     <ttnn:tap name="tapb0b4a106-d0">89.234.156.248</ttnn:tap>

   </ttnn:config>

  * On top in metadata remove <nova:instance ...></nova:instance> section

* virsh destroy $id

* virsh undefine $id

* virsh define myvm.xml

* virsh start <my_new_name>