How Client Configurations are Deployed

Client configuration files are deployed on any host that is a client for a service—that is, that has a role for the service on that host. This includes roles such as DataNodes, TaskTrackers, RegionServers and so on as well as gateway roles for the service.

If roles for multiple services are running on the same host (for example, a DataNode role and a TaskTracker role on the same host) then the client configurations for both roles are deployed on that host, with the alternatives priority determining which configuration takes precedence.

For example, suppose we have six hosts running roles as follows: host H1: HDFS-NameNode; host H2: MR-JobTracker; host H3: HBase-Master; host H4: MR-TaskTracker, HDFS-DataNode, HBase-RegionServer; host H5: MR-Gateway; host H6: HBase-Gateway. Client configuration files will be deployed on these hosts as follows: host H1: hdfs-clientconfig (only); host H2: mapreduce-clientconfig, host H3: hbase-clientconfig; host H4: hdfs-clientconfig, mapreduce-clientconfig, hbase-clientconfig; host H5: mapreduce-clientconfig; host H6: hbase-clientconfig

If the HDFS NameNode and MapReduce JobTracker were on the same host, then that host would have both hdfs-clientconfig and mapreduce-clientconfig installed.