Ceph rbdmap.service fails to start during reboot, causing RBD Images to fail to be mapped

Issue

• During reboot of a host using Ceph RBD images, the rbdmap.service fails to map RBD images.

• Logs shown by journalctl during the boot process include:

  $DATE_TIME $HOSTNAME systemd[1]: Starting Map RBD devices...
  $DATE_TIME $HOSTNAME kernel: rbd: loaded (major 252)
  $DATE_TIME $HOSTNAME rbdmap[4239]: Failed to map 'NFS/NFSImage
  $DATE_TIME $HOSTNAME systemd[1]: rbdmap.service: Main process exited, code=exited, status=1/FAILURE
  $DATE_TIME $HOSTNAME systemd[1]: rbdmap.service: Failed with result 'exit-code'.
  $DATE_TIME $HOSTNAME systemd[1]: Failed to start Map RBD devices.
  $DATE_TIME $HOSTNAME0 audispd[2488]: type=SERVICE_START msg=audit(1618498340.030:60): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=rbdmap comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed' UID="root" AUID="unset"
  

• After a reboot, Systemd shows the rbdmap.service has failed:

  # systemctl status rbdmap.service
  ● rbdmap.service - Map RBD devices
  Loaded: loaded (/usr/lib/systemd/system/rbdmap.service; enabled; vendor preset: disabled)
     Active: failed (Result: exit-code) since $DATE_TIME; 1min 13s ago
    Process: 3419 ExecStart=/usr/bin/rbdmap map (code=exited, status=1/FAILURE)
   Main PID: 3419 (code=exited, status=1/FAILURE)
  

• However, restarting the rbdmap.service after the reboot with the command systemctl start rbdmap.service succeeds.