Use following command to download images from OpenStack glance.
source overcloudrc
openstack image save --file file-name.qcow2 image-name-or-id
if you would like to download and compress at the same time use
source overcloudrc
openstack image save image-name-or-id | gzip -c > image-name.raw.gz
For example:
[stack@ospdir ~]$ source overcloudrc
(admin@overcloud) [stack@ospdir ~]$ openstack image list -c ID -c Name -c "Disk Format" -c Size -f table --long
+--------------------------------------+----------+-------------+-------------+
| ID | Name | Disk Format | Size |
+--------------------------------------+----------+-------------+-------------+
| 6c5384f6-cf86-4a41-b9d4-8cafbb9c08fc | CentOS74 | qcow2 | 854851584 |
| 4d43fb6d-16a3-4c85-8eab-f0088a9f5aaa | Win2k16 | raw | 42954915840 |
| 3bcdeb04-9170-4f2c-8468-8797477b6c02 | cirros | qcow2 | 13267968 |
+--------------------------------------+----------+-------------+-------------+
(admin@overcloud) [stack@ospdir ~]$ openstack image save Win2K16 | gzip -c > Win2K16.raw.gz
(admin@overcloud) [stack@ospdir ~]$ du -b Win2k16.raw.gz 9151990788 Win2k16.raw.gz
(admin@overcloud) [stack@ospdir ~]$ openstack image save --file cirros.qcow2 cirros
(admin@overcloud) [stack@ospdir ~]$ du -b cirros.qcow2 13267968 Win2k16.raw.gz
