When targeting OpenStack Wallaby lots of Nova metrics openstack_nova_*, like openstack_nova_memory_used_bytes are not returned anymore. This is due to the deprecation / move of quite a list of metrics for Nova towards Placement:

    current_workload
    cpu_info
    vcpus
    vcpus_used
    free_disk_gb
    local_gb
    local_gb_used
    disk_available_least
    free_ram_mb
    memory_mb
    memory_mb_used
    running_vms

see https://docs.openstack.org/nova/wallaby/reference/api-microversion-history.html#maximum-in-wallaby

Certainly pinning the API to the latest version still returning this data ( OS_COMPUTE_API=2.87) works,
but this adds to similar issues when using the exporter with more recent OS versions:

• openstack exporter nova_server_status fails to return flavor id #220
• openstack_nova_security_groups metric unavailable  #221