使用root用户配置的hadoop集群启动报错：ERROR: Attempting to operate on hdfs namenode as root_error: refusing to run as root: hdfs account is no

前几天在虚拟机上自己搭建了一个集群，然后因为工作就一直也没管。今天启动的时候，发现报错了。还以为是自己在搭建的时候有问题呢。然后第二次搭建完成之后，启动还是报错。就上网查。
大致报错信息如下：

[root@master hadoop]# start-dfs.sh 
Starting namenodes on [master]
ERROR: Attempting to operate on hdfs namenode as root
ERROR: but there is no HDFS_NAMENODE_USER defined. Aborting operation.
Starting datanodes
ERROR: Attempting to operate on hdfs datanode as root
ERROR: but there is no HDFS_DATANODE_USER defined. Aborting operation.
Starting secondary namenodes [master]
ERROR: Attempting to operate on hdfs secondarynamenode as root
ERROR: but there is no HDFS_SECONDARYNAMENODE_USER defined. Aborting operation.

[root@master hadoop]# start-yarn.sh 
Starting resourcemanager
ERROR: Attempting to operate on yarn resourcemanager as root
ERROR: but there is no YARN_RESOURCEMANAGER_USER defined. Aborting operation.
Starting nodemanagers
ERROR: Attempting to operate on yarn nodemanager as root
ERROR: but there is no YARN_NODEMANAGER_USER defined. Aborting operation.
[root@master hadoop]# 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

解决方法：
修改hadoop安装目录下的 etc/hadoop 下的 hadoop-env.sh文件。添加下面几行内容：
就添加在最上面就行。

export HDFS_NAMENODE_USER=root
export HDFS_DATANODE_USER=root
export HDFS_JOURNALNODE_USER=root
export HDFS_ZKFC_USER=root
export YARN_RESOURCEMANAGER_USER=root
export YARN_NODEMANAGER_USER=root
export HDFS_SECONDARYNAMENODE_USER=root
1
2
3
4
5
6
7

然后再启动，就没问题了。