Inspect Hadoop configuration using command-line.
Hadoop provides a utility to get necessary configuration information.
$ hdfs getconf
hdfs getconf is utility for getting configuration information from the config file.
hadoop getconf
[-namenodes] gets list of namenodes in the cluster.
[-secondaryNameNodes] gets list of secondary namenodes in the cluster.
[-backupNodes] gets list of backup nodes in the cluster.
[-journalNodes] gets list of journal nodes in the cluster.
[-includeFile] gets the include file path that defines the datanodes that can join the cluster.
[-excludeFile] gets the exclude file path that defines the datanodes that need to decommissioned.
[-nnRpcAddresses] gets the namenode rpc addresses
[-confKey [key]] gets a specific key from the configuration
Display name nodes.
$ hdfs getconf -namenodes
namenode.example.org
Display secondary name nodes.
$ hdfs getconf -secondaryNameNodes
secondarynamenode.example.org
Display name node RPC addresses.
$ hdfs getconf -nnRpcAddresses
namenode.example.org:9000
Display include file path.
$ hdfs getconf -includeFile
/opt/hadoop/hadoop-3.2.2/etc/hadoop/includes
Display exclude file path.
$ hdfs getconf -excludeFile
Configuration dfs.hosts.exclude is missing.
Display specific configuration key.
$ hdfs getconf -confKey dfs.namenode.datanode.registration.ip-hostname-check
true
$ hdfs getconf -confKey dfs.namenode.checkpoint.period
3600s
Use exit code to determine if configuration key is missing.
