...

  - targets:
    - localhost:9191
 to 
  - targets:
    - wolf-118:9191
    - wolf-119:9191
    - wolf-120:9191
    - wolf-121:9191

(mjmac) It's worth noting here that if you add the hosts to your ~/.daos_control.yml or some other control config file that you use with dmg -o /path/to/config.yml, they will automatically be added to your prometheus configuration.

Starting Prometheus

./prometheus --config_file=~/.prometheus.yml;

...