compute: Add [compute-feature-enabled]ide_bus flag
This change adds a specific flag to allow environments to indicate that
they do not support an IDE bus being used to attach devices to an
instance.
This is required as Nova's libvirt driver is looking to default to the
newer QEMU machine types such as ``q35`` in the future [1]. These newer
machine types have dropped support for the IDE bus in favour of the more
modern SATA, SCSI and VirtIO buses. As such in the longer term it cannot
be assumed that the IDE bus will always be available and in the short
term we need a way to indicate that an environment doesn't support IDE
when it's using the ``q35`` machine type.
For now the flag defaults to True but will need to move to False if Nova
ever defaults to the ``q35`` machine type.
[1] https://specs.openstack.org/openstack/nova-specs/specs/wallaby/approved/libvirt-stash-instance-machine-type.html
Change-Id: I40824fc3c88f16050407e52a790dd162f1f67e3a
diff --git a/releasenotes/notes/add-compute-feature-ide-bus-b63802502c378083.yaml b/releasenotes/notes/add-compute-feature-ide-bus-b63802502c378083.yaml
new file mode 100644
index 0000000..43a0e8c
--- /dev/null
+++ b/releasenotes/notes/add-compute-feature-ide-bus-b63802502c378083.yaml
@@ -0,0 +1,10 @@
+---
+other:
+ - |
+ A new ``[compute-feature-enabled]ide_bus`` config option has been
+ introduced to indicate if the environment supports attaching disks to an
+ instance using an ``IDE`` bus.
+
+ This currently defaults to ``True`` but should be set to ``False`` when
+ using the libvirt OpenStack Nova virt driver *and* the ``q35`` machine type
+ as support for this bus is no longer provided.