搭建Hadoop Yarn on Docker环境，一切准备就绪后运行如下 命令
hadoop jar $HADOOP_PREFIX/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.0.jar \ teragen \
-Dmapreduce.map.env="yarn.nodemanager.docker-container-executor.image-name=sequenceiq/hadoop-docker:latest" \
-Dyarn.app.mapreduce.am.env="yarn.nodemanager.docker-container-executor.image-name=sequenceiq/hadoop-docker:latest"\
1000 \ teragen_out_dir
总是报Container image must not be null ？？？
求教各位大神（个人感觉是这环境变量没传过去，可又无从下手）
详细信息如下：
java.lang.IllegalArgumentException: Container image must not be null at com.google.common.base.Preconditions.checkArgument(Preconditions.java:88) at org.apache.hadoop.yarn.server.nodemanager.DockerContainerExecutor.launchContainer(DockerContainerExecutor.java:189) at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.launchContainer(ContainerLaunch.java:437) at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:288) at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:92) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
