Since the configuration is hadoop-2.7.1, it will be found later during startup

The terminal executes./start yarn sh
starting yarn daemons
Error: Cannot find configuration directory: /etc/hadoop
Error: Cannot find configuration directory: /etc/hadoop

This is the reason why the directory cannot be found. You can find the solution by reading the corresponding shell script~

Solution:

Configures the directory where a Hadoop configuration file is located in hadoop-env.sh (codes as below):

export HADOOP_CONF_DIR=/opt/hadoop-2.7.1/etc/hadoop/

Execute command

source  hadoop-env.sh