We need to set up a process that will allow us to receive email alerts based on Hadoop metrics from Cloudera Manager. E.g. a particular service going down, more than 10 datanodes getting blacklisted etc. What would be best way to achieve this in CM version 5.1?
Did you try looking in the Cloudera Manager under Administration->Alerts? There's quite a bit of built-in monitoring and alert configuration options there. With regards to your example, there is a specific setting for "DataNode health" under the HDFS alerts.