Comment 2 for bug 1533536

Glance does have out-of-the box parameter 'checksum'. I guess that's why you cannot create the custom parameter with the same name. Just execute glance image-show <image ID> and you will see the checksum here:
+------------------+--------------------------------------+
| Property | Value |
+------------------+--------------------------------------+
| checksum | eb9139e4942121f22bbc2afc0400b2a4 |
| container_format | ami |
| created_at | 2015-12-10T10:52:43Z |
| disk_format | ami |
| id | b3eb6179-43f6-4956-8ed3-010e03bccd83 |
| kernel_id | 1f9fb6bc-b3b0-47d7-8160-633a88a893e9 |
| min_disk | 0 |
| min_ram | 0 |
| name | cirros-0.3.4-x86_64-uec |
| owner | c838177f128c4defa5fe6a6d5b1da48c |
| protected | False |
| ramdisk_id | 349095ef-002e-4001-b033-1fe21ac1ad44 |
| size | 25165824 |
| status | active |
| tags | [] |
| updated_at | 2015-12-10T10:52:44Z |
| virtual_size | None |
| visibility | public |
+------------------+--------------------------------------+
Does it satisfy your goals?
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Now I am marking this as Invalid.