nova/releasenotes/notes/bug-1748697-COMPUTE_SAME_HOST_COLD_MIGRATE-19ed64bf48bb1fc7.yaml
Matt Riedemann 4921e822e7 Use COMPUTE_SAME_HOST_COLD_MIGRATE trait during migrate
This uses the COMPUTE_SAME_HOST_COLD_MIGRATE trait in the API during a
cold migration to filter out hosts that cannot support same-host cold
migration, which is all of them except for the hosts using the vCenter
driver.

For any nodes that do not report the trait, we won't know if they don't
because they don't support it or if they are not new enough to report
it, so the API has a service version check and will fallback to old
behavior using the config if the node is old. That compat code can be
removed in the next release.

As a result of this the FakeDriver capabilities are updated so the
FakeDriver no longer supports same-host cold migration and a new fake
driver is added to support that scenario for any tests that need it.

Change-Id: I7a4b951f3ab324c666ab924e6003d24cc8e539f5
Closes-Bug: #1748697
Related-Bug: #1811235
2020-01-29 09:44:47 +00:00

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YAML

---
fixes:
- |
This release contains a fix for `bug 1748697`_ which distinguishes between
resize and cold migrate such that the ``allow_resize_to_same_host`` config
option is no longer used to determine if a server can be cold migrated to
the same compute service host. Now when requesting a cold migration the
API will check if the source compute node resource provider has the
``COMPUTE_SAME_HOST_COLD_MIGRATE`` trait and if so the scheduler can select
the source host. Note that the only in-tree compute driver that supports
cold migration to the same host is ``VMwareVCDriver``.
To support rolling upgrades with N-1 computes if a node does not report the
trait and is old the API will fallback to the ``allow_resize_to_same_host``
config option value. That compatibility will be removed in a subsequent
release.
.. _bug 1748697: https://launchpad.net/bugs/1748697