To Reproduce Steps to reproduce the behavior:

1. Create some big VMs in an openstack cloud
2. Make high cpu usage on it
3. Create any audit that trigger instance live migration (host_maintenance, i.e.)
4. The VM fails to migrate

Expected behavior

• Instance should migrate properly

Bug impact

• Please provide information on the impact of this bug to the end user.

Known workaround

• Not workaround is available.

Additional context

In some cases, specially for non-small virtual machines migrate actions fail.

Root cause is that the migration is taking in nova more than 120 seconds which is a hardcoded timeout in watcher code.

the helper method in nova_helper is setting 120s by default

https://github.com/openstack/watcher/blob/45cc5b9d8ba9e82d20d21d4b3eabcaf6992b26e2/watcher/common/nova_helper.py#L303

And the migrate action is not exposing the timeout as a parametrizable value

https://github.com/openstack/watcher/blob/45cc5b9d8ba9e82d20d21d4b3eabcaf6992b26e2/watcher/applier/actions/migration.py#L119-L120