Setting instance default_ephemeral_device in Ironic driver should be more intelligent

[David Shrewsbury]

The instance default_ephemeral_device value needs to be set within the nova driver to the partition where the ephemeral partition is created. We currently hard code this value to /dev/sda1 to duplicate the old nova-bm behavior. While this makes things work for TripleO [1], we should do something smarter to determine the true partition value to set (e.g., a Cirros image value should be /dev/vda1).

We could consider using something like udev by-label names (e.g., /dev/disk/by-label/NNN). This obviously adds a requirement on udev.

[1] https://bugs.launchpad.net/ironic/+bug/1324286

[Dmitry Tantsur (divius)]

For future implementer: please note that this change definitely requires a proper spec.

[John L. Villalovos (happycamp)]

This should be changed to 'Wishlist' as it is a request for an improvement.

[Markus Zoeller (markus_z) (mzoeller)]

This wishlist bug has been open a year without any activity. I'm going
to move it to "Opinion / Wishlist", which is an easily-obtainable queue
of older requests that have come on. If you decide to work on this
consider using a blueprint [1] (maybe with a spec [2]). I'll recommend to
read [3] if not yet done.

References:
[1] https://blueprints.launchpad.net/nova/
[2] https://github.com/openstack/nova-specs
[3] https://wiki.openstack.org/wiki/Blueprints

[Galyna Zholtkevych (gzholtkevych)]

Hello!

In case of ironic usage this bug seems invalid.
When deploying instance with ephemeral flavor, this option
default_ephemeral_device in any appropriate mountpoints.

See http://paste.openstack.org/show/585931/

[Michael Turek (mjturek)]

This wishlist bug has been open more than a year without any activity. I'm going to move it to "Opinion / Wishlist", which is an easily-obtainable queue of older requests that have come on. This bug can be reopened (set back to "New") if someone decides to work on this.