rebuild instance will delete instance's image_base_image_ref

[Chaolei Li]

When i rebuild an instance with a base image that has no property of base_image_ref, i find that the instance's system_metadada image_base_image_ref will be deleted not updated.
Here is the system_metadata of an instance:
$ MariaDB [nova]> select * from instance_system_metadata where instance_uuid = "f885595b-7b3d-4b5d-a91d-5c894473c9ad";
+---------------------+------------+------------+--------+--------------------------------------+---------------------------+--------------------------------------+---------+
| created_at | updated_at | deleted_at | id | instance_uuid | key | value | deleted |
+---------------------+------------+------------+--------+--------------------------------------+---------------------------+--------------------------------------+---------+
| 2017-04-17 10:16:07 | NULL | NULL | 111215 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_disk_format | qcow2 | 0 |
| 2017-04-17 10:16:07 | NULL | NULL | 111216 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_container_format | bare | 0 |
| 2017-04-17 10:16:07 | NULL | NULL | 111217 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_min_ram | 0 | 0 |
| 2017-04-17 10:16:07 | NULL | NULL | 111218 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_min_disk | 20 | 0 |
| 2017-04-17 10:16:07 | NULL | NULL | 111219 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_base_image_ref | ef9258de-4faa-41d4-809f-8f9a990cb3e2 | 0 |
| 2017-04-17 10:16:07 | NULL | NULL | 111220 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_hw_qemu_guest_agent | yes | 0 |
+---------------------+------------+------------+--------+--------------------------------------+---------------------------+--------------------------------------+---------+
Now we rebuild this instance choosing a base image.
$ nova rebuild f885595b-7b3d-4b5d-a91d-5c894473c9ad 7ceb073b-6d37-4e0d-91af-ee911e29fc81
$ MariaDB [nova]> select * from instance_system_metadata where instance_uuid = "f885595b-7b3d-4b5d-a91d-5c894473c9ad";
+---------------------+---------------------+---------------------+--------+--------------------------------------+---------------------------+--------------------------------------+---------+
| created_at | updated_at | deleted_at | id | instance_uuid | key | value | deleted |
+---------------------+---------------------+---------------------+--------+--------------------------------------+---------------------------+--------------------------------------+---------+
| 2017-04-17 10:16:07 | NULL | NULL | 111215 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_disk_format | qcow2 | 0 |
| 2017-04-17 10:16:07 | NULL | NULL | 111216 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_container_format | bare | 0 |
| 2017-04-17 10:16:07 | 2017-04-18 06:47:38 | NULL | 111217 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_min_ram | 0 | 0 |
| 2017-04-17 10:16:07 | 2017-04-18 06:47:38 | NULL | 111218 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_min_disk | 20 | 0 |
| 2017-04-17 10:16:07 | 2017-04-18 06:47:38 | 2017-04-18 06:47:38 | 111219 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_base_image_ref | ef9258de-4faa-41d4-809f-8f9a990cb3e2 | 111219 |
| 2017-04-17 10:16:07 | NULL | NULL | 111220 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | image_hw_qemu_guest_agent | yes | 0 |
| 2017-04-18 06:47:42 | NULL | NULL | 111463 | f885595b-7b3d-4b5d-a91d-5c894473c9ad | clean_attempts | 1 | 0 |
+---------------------+---------------------+---------------------+--------+--------------------------------------+---------------------------+--------------------------------------
we can see that the image_min_ram and image_min_disk are updated but the image_base_image_ref is deleted.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/457514

[Alex Xu (xuhj)]

i'm curious why we need 'image_base_image_ref' in the system_metadata, i didn't found it is very useful.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Chaolei Li (<email address hidden>) on branch: master
Review: https://review.openstack.org/457514