diskimage-builder 2GB image does not boot in 2GB flavor

[Michael Johnson]

The Octavia project uses disk-image-create to build the amphora service VM image. We use the --image-size 2 setting to generate a 2GB image that boots in a 2GB Nova flavor.

Recently we have started to get the following error from Nova with newly created images:

n-cpu.log.2015-11-04-172820:2015-11-05 09:59:49.644 TRACE nova.compute.manager [instance: 76d91eed-8cbc-47d4-b59e-1d10a0ee7c31] FlavorDiskSmallerThanImage: Flavo 's disk is too small for requested image. Flavor disk is 2147483648 bytes, image is 2214658048 bytes.

This causes a 2GB diskimage-builder image to not boot in a 2GB flavor an longer.

[Michael Johnson (johnsom)]

Suspect patch:
https://github.com/openstack/diskimage-builder/commit/f84b910f152220294a723836a71586974efadede

[Ben Nemec (bnemec)]

This is most likely caused by https://github.com/openstack/diskimage-builder/commit/f84b910f152220294a723836a71586974efadede

It moved the ext4 size manipulation code out of the else block so it will get run even when a specific image size is provided. I think we should move it back to the else block, which will hopefully fix this problem, and even if it doesn't that was a backwards compatibility breaking change since it's not how this worked before.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/242273

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/242273
Committed: https://git.openstack.org/cgit/openstack/diskimage-builder/commit/?id=590dce8dcc70949f5e60fbab205d777ed31c282a
Submitter: Jenkins
Branch: master

commit 590dce8dcc70949f5e60fbab205d777ed31c282a
Author: Michael Johnson <email address hidden>
Date: Thu Nov 5 21:49:28 2015 +0000

    Fix diskimage-builder image size

    This patch fixes the calculation of the resultant image size
    when building an image with diskimage-builder on ext4 a
    filesystem.

    Prior to this, using the '--image-size 2' (2GB) setting would
    generate an image that would not boot under a 2GB nova flavor.

    Change-Id: I7a753bdef84c6300ccea73ae4a92bf330dcd77cb
    Closes-Bug: #1513622