Error Message "error creating DomainSocket" Is Displayed When the HDFS Client Installed on the Core Node in a Normal Cluster Is Used

Issue

In a normal cluster, an error message is displayed when a user is created on the core node to install the HDFS client.

Symptom

In a common cluster, the following error message is displayed when a user is created on the Core node to install the client:

2020-03-14 19:16:17,166 WARN shortcircuit.DomainSocketFactory: error creating DomainSocket
java.net.ConnectException: connect(2) error: Permission denied when trying to connect to '/var/run/MRS-HDFS/dn_socket'
at org.apache.hadoop.net.unix.DomainSocket.connect0(Native Method)
at org.apache.hadoop.net.unix.DomainSocket.connect(DomainSocket.java:256)
at org.apache.hadoop.hdfs.shortcircuit.DomainSocketFactory.createSocket(DomainSocketFactory.java:168)
at org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.nextDomainPeer(BlockReaderFactory.java:799)
...

Cause Analysis

A user runs the useradd command to create a user. The default user group of the user does not contain the ficommmon user group. As a result, the preceding error is reported when the get command of HDFS is executed.

Procedure

Run the usermod -a -G ficommon username command to add the user to the ficommon user group.