diskimage-builder: fails to build CentOS 7 image

[Martin Chlumsky]

This bug was originally filed in the octavia project: https://storyboard.openstack.org/#!/story/2008030

Building CentOS 7 image fails because the image url is incorrect.

2020-08-18 21:43:04.251 | > GET /centos/7/images/CentOS-7-x86_64-7.qcow2.xz HTTP/1.1
2020-08-18 21:43:04.251 | > Host: cloud.centos.org
2020-08-18 21:43:04.251 | > User-Agent: curl/7.69.1
2020-08-18 21:43:04.251 | > Accept: */*
2020-08-18 21:43:04.251 | >
2020-08-18 21:43:04.293 | * Mark bundle as not supporting multiuse
2020-08-18 21:43:04.293 | < HTTP/1.1 404 Not Found

Digging through the debug output (attached) it seems that the variable is set to "7":

2020-08-19 00:41:18.905 | ++ /tmp/dib_build.4ZMxOJGs/hooks/environment.d/09-centos7-distro-name.bash:source:2 : export DIB_FLAVOR=7
2020-08-19 00:41:18.907 | ++ /tmp/dib_build.4ZMxOJGs/hooks/environment.d/09-centos7-distro-name.bash:source:2 : DIB_FLAVOR=7

But it needs to be either not be set or set to "GenericCloud" as per this line:

https://github.com/openstack/diskimage-builder/blob/master/diskimage_builder/elements/centos/root.d/10-centos-cloud-image#L50

The final url should be: https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud.qcow2.xz

[Carlos Goncalves (cgoncalves)]

Please note that diskimage-builder is capped to 2.30.0 in stable/stein requirements.

https://github.com/openstack/requirements/blob/8dd9d2c04c9b0f8a9cc0c0baad5112f2180f95b7/upper-constraints.txt#L511-L515