权限和 owner

当 Hadoop, YARN 以 Secure Mode (使用 Kerberos 认证) 部署时, 必须使用 LinuxContainer

<property>
    <name>yarn.nodemanager.container-executor.class</name>
    <value>org.apache.hadoop.yarn.server.nodemanager.LinuxContainerExecutor</value>
</property>

否则会报错

ERROR org.apache.hadoop.mapred.ShuffleHandler: Shuffle error : java.io.IOException: Error Reading IndexFile

可参考: Reduce phase is failing with shuffle error in kerberos enabled cluster

HADOOP_HOME 下的 bin/container-executor 和 etc/hadoop/container-executor.cfg 对权限和 ower 都有要求:

1. 参考: Configure the Linux Container
2. 要求 container-executor.cfg 的所有父目录 owner 都为 root.

配置好后, 可以运行:

./bin/container-executor --checksetup

如果配置有误, 则会输出错误信息.

配置文件的坑

1. 配置项末尾不能有空格.

   我的配置:

    #configured value of yarn.nodemanager.linux-container-executor.group
    yarn.nodemanager.linux-container-executor.group=hadoop
    #comma separated list of users who can not run applications
    banned.users=root
    #Prevent other super-users
    min.user.id=500
    ##comma separated list of system users who CAN run applications
    allowed.system.users=hadoop
   

   checksetup 总是报错:

    Can't get group information for hadoop  - Success.
   

   Google 得到的结果都不能解决.

   查看源码有:

    struct group *group_info = getgrnam(nm_group);
    if (group_info == NULL) {
    fprintf(ERRORFILE, "Can't get group information for %s - %s.\n", nm_group,
            strerror(errno));
    flush_and_close_log_files();
    exit(INVALID_CONFIG_FILE);
    }
   

   但是很明显, 测试也表明,

    const char *nm_group = "hadoop";
    struct group *group_info = getgrnam(nm_group);
   

   是可以得到正确结果的. 继续 check, 发现是配置中

    yarn.nodemanager.linux-container-executor.group=hadoop
   

   末尾有空格导致. 真让人对代码质量大跌眼镜, 看样子 hadoop 的开发者也不全是大牛.

   此问题在 Hadoop 2.5.2 和 2.6.0 中测试都存在.

2. 如果文件以 CRLF 换行, 则会报错:

    configuration tokenization failed
    Can't get configured value for yarn.nodemanager.linux-container-executor.group.
   

   需要使用 dos2unix 转换.

   可以用 file container-executor.cfg 检查文件格式:

    # unix format
    etc/hadoop/container-executor.cfg: ASCII text
   
    # dos format
    etc/hadoop/container-executor.cfg: ASCII text, with CRLF line terminators  
   

3. 如果 banned.users= 为空, 也会报上面的错误.