Rudder

If an agent is hosted on a host with an uppercase hostname, it can be refused by the server.

The problem is from cf-serverd that refuses it.
To work around it, edit /var/rudder/configuration-repository/techniques/system/common/1.0/cf-served.st and change the access rules to force lower case :

  &if(SKIPIDENTIFY)&
    &MANAGED_NODES_NAME, MANAGED_NODES_ID : {host, uuid |
      "/var/rudder/share/&uuid&/" 
        maproot => { string_downcase(escape("&host&"))  },
        admit   => { string_downcase(escape("&host&"))  };

     } &
  &else&
    &MANAGED_NODES_NAME, MANAGED_NODES_ID : {host, uuid |
      "/var/rudder/share/&uuid&/" 
        maproot => { host2ip("&host&"), string_downcase(escape("&host&"))  },
        admit   => { host2ip("&host&"), string_downcase(escape("&host&"))  };

     } &
  &endif&