Comment 5 for bug 1544044

So, this is a new feature that added new API to force live migration to complete. It can be used on a VM that is being live migrated (task state MIGRATING) and right now it is supported only when libvirt is used as a virt driver. Basically it pauses a VM, so that it does not write to memory which means that live migration will end in a finite time because of no dirty pages. Two typical use cases for this feature are:

* Live migration is stuck but you really need to move an instance to another host
* Live migration is taking long time but it's a critical case and you need to finish it ASAP

VM is automatically unpaused at the end of the process, even if the process fails. By default attached policy allows admins only to use this feature.

New API call is:
POST /servers/<instance_uuid>/migrations/<migration_id>/action
Body: {'force_complete': null}
Through CLI: nova live-migration-force-complete <instance_uuid/name> <migration_id>

Migration ID can be obtained by listing all in-progress live migrations for particular instance:
GET /servers/<instance_uuid>/migrations
Through CLI: nova server-migration-list <instance_uuid/name>