this bug might already fixed, i tried to reproduce but failed with devstack.
[stack@devstack devstack]$ openstack server create --image centos7 --flavor ds1G --network f2a39df5-0938-4973-9810-a80d341229bf --user-data /tmp/data test1
+-------------------------------------+------------------------------------------------+
| Field | Value |
+-------------------------------------+------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | |
| OS-EXT-SRV-ATTR:host | None |
| OS-EXT-SRV-ATTR:hypervisor_hostname | None |
| OS-EXT-SRV-ATTR:instance_name | |
| OS-EXT-STS:power_state | NOSTATE |
| OS-EXT-STS:task_state | scheduling |
| OS-EXT-STS:vm_state | building |
| OS-SRV-USG:launched_at | None |
| OS-SRV-USG:terminated_at | None |
| accessIPv4 | |
| accessIPv6 | |
| addresses | |
| adminPass | TuHp5eHEMMfW |
| config_drive | |
| created | 2019-12-06T10:32:10Z |
| flavor | ds1G (d2) |
| hostId | |
| id | afdecb55-f3e1-4099-b947-1704112cb9ae |
| image | centos7 (2f2396d2-b32e-4275-93b3-df9fb376dc36) |
| key_name | None |
| name | test1 |
| progress | 0 |
| project_id | 9aafb875525b45b79be2d1ca5d27ffb0 |
| properties | |
| security_groups | name='default' |
| status | BUILD |
| updated | 2019-12-06T10:32:10Z |
| user_id | d994888b0c764c8288cc1162f69b8d8b |
| volumes_attached | |
+-------------------------------------+------------------------------------------------+
[stack@devstack devstack]$ curl -H 'X-Forwarded-For: 192.168.199.151' http://localhost:8775/latest/user-data/
400 Bad Request
400 Bad Request
X-Instance-ID header is missing from request.