因此，我在一个由三节点awsec2示例组成的集群上安装了ambari。所有服务都显示为绿色，也就是说，它们似乎都运行良好。我可以做所有的hdfs文件操作。但是，每当我尝试在示例上运行一个简单的wordcount程序时，它都会说它无法到达端口8020。

$ hadoop jar /usr/hdp/2.2.6.3-1/hadoop-mapreduce/hadoop-mapreduce-examples-2.6.0.2.2.6.3-1.jar wordcount  /tmp/wordcount/in /tmp/wordcount/out
15/08/21 05:28:02 INFO impl.TimelineClientImpl: Timeline service address: http://<fqdn for the namenode>:8188/ws/v1/timeline/
15/08/21 05:28:02 INFO client.RMProxy: Connecting to ResourceManager at <fqdn for the namenode>/10.0.0.55:8050
java.io.FileNotFoundException: File does not exist: hdfs://<fqdn for the namenode>:8020/hdp/apps/2.2.6.3-1/mapreduce/mapreduce.tar.gz
    at org.apache.hadoop.fs.Hdfs.getFileStatus(Hdfs.java:137)
    at org.apache.hadoop.fs.AbstractFileSystem.resolvePath(AbstractFileSystem.java:460)
    at org.apache.hadoop.fs.FileContext$25.next(FileContext.java:2180)
    at org.apache.hadoop.fs.FileContext$25.next(FileContext.java:2176)
    at org.apache.hadoop.fs.FSLinkResolver.resolve(FSLinkResolver.java:90)
    at org.apache.hadoop.fs.FileContext.resolve(FileContext.java:2176)
    at org.apache.hadoop.fs.FileContext.resolvePath(FileContext.java:595)
    at org.apache.hadoop.mapreduce.JobSubmitter.addMRFrameworkToDistributedCache(JobSubmitter.java:753)
    at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:435)
    at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1296)
    at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1293)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:415)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
    at org.apache.hadoop.mapreduce.Job.submit(Job.java:1293)
    at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1314)
    at org.apache.hadoop.examples.WordCount.main(WordCount.java:87)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:71)
    at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144)
    at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.hadoop.util.RunJar.run(RunJar.java:221)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:136)

fqdn是命令的输出 hostname -f 创建群集时使用的。
我也尝试过telnet，但是有太多的连接被拒绝了。

bt-prod-dev-02@ip-10-0-0-55:~$  telnet localhost 8020
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

我不知道该去哪儿找。