Error on booting instance with ephemeral while using Flat/Raw images

[Timofey Durakov]

Description
===========
When using Flat/Raw image type in nova, and flavors with none-empty ephemerals, instance fails to boot.

Steps to reproduce
==================
1. create flavor with non-empty ephemeral
2. Boot instance with flavor from step 1.

Expected result
===============
Instance become active

Actual result
=============
Instance moved to ERROR state

Environment
===========
1. stack@node1:/opt/stack/nova$ git log -1
commit d23fb5ff9f10559681adc04b5b4116cfb0ede9df
Merge: 6a5e36f 630eed5
Author: Jenkins <email address hidden>
Date: Wed Aug 17 14:47:19 2016 +0000

    Merge "Make simple_cell_setup work when multiple nodes are present"

2. Libvirt 1.3.1

2. No shared storage

Logs & Configs
==============
nova.conf:
use_cow_images = False

on that compute node.

2016-08-18 11:46:15.451 ERROR nova.compute.manager [req-8b08cc99-5b5c-4a18-8306-142a38673dce admin admin] [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] Instance failed to spawn
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] Traceback (most recent call last):
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/compute/manager.py", line 2075, in _build_resources
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] yield resources
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/compute/manager.py", line 1919, in _build_and_run_instance
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] block_device_info=block_device_info)
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 2650, in spawn
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] admin_pass=admin_password)
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 3131, in _create_image
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] specified_fs=specified_fs)
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/virt/libvirt/imagebackend.py", line 221, in cache
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] if size > self.get_disk_size(base):
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/virt/libvirt/imagebackend.py", line 275, in get_disk_size
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] return disk.get_disk_size(name)
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/virt/disk/api.py", line 148, in get_disk_size
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] return images.qemu_img_info(path).virtual_size
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] File "/opt/stack/nova/nova/virt/images.py", line 51, in qemu_img_info
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] raise exception.DiskNotFound(location=path)
2016-08-18 11:46:15.451 TRACE nova.compute.manager [instance: 4317b4fe-bba2-4b92-bbe9-73506229bb22] DiskNotFound: No disk at /opt/stack/data/nova/instances/_base/ephemeral_3_40d1d2c