For posterity this seems to be an issue in CM 5.12 and a fix is scheduled to be available in CM 5.12.x maintenance release. - workaround posted in    [0] http://community.cloudera.com/t5/Cloudera-Manager-Installation/Installation-failed-Failed-to-receive-heartbeat-from-agent/m-p/58809#M11660 http://community.cloudera.com/t5/Cloudera-Manager-Installation/Cloudera-Manager-Agent-cannot-connect-with-supervisor-Failed-to/td-p/58522 http://community.cloudera.com/t5/Cloudera-Manager-Installation/CDH-5-12-0-clouder-manager-agent-can-not-start/m-p/58726 ... View more