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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6776) distcp from insecure cluster (source) to secure cluster (destination) doesn't work via webhdfs
Date Fri, 05 Sep 2014 18:32:29 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6776?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14123333#comment-14123333
] 

Yongjun Zhang commented on HDFS-6776:
-------------------------------------

Hi [~wheat9], 

I know that you are opposed to put the msg-parsing hack to webhdfs. However, you also have
said:
{quote}
However, it's okay to me to return a null here so the behavior is similar to DistributedFileSystem.
The actual fallback logic can happen at the distcp side when building the file list, but maybe
we can defer it to another jira.
{quote}

I had quite some questions for you in my last two comments, I'd appreciate that you could
comment on them. That way, we can understand more about your concern why it's so fragile as
you said. 

Do you agree that a correct webhdfs contract is not to fail with the exception when accessing
insecure cluster, rather, it should be able to access insecure cluster? This is a very important
question that I hope you could answer.

We agree that the msg-parsing is a bit hacky, but why hack in webhdfs is so much worse than
in distcp, given webhdfs doesn't work without a fix?

BTW, FYI, not to say that it's good thing to do so, there was already code doing msg parsing
in webhdfs:
{code}
      // extract UGI-related exceptions and unwrap InvalidToken
      // the NN mangles these exceptions but the DN does not and may need
      // to re-fetch a token if either report the token is expired
      if (re.getMessage().startsWith("Failed to obtain user group information:")) {
        String[] parts = re.getMessage().split(":\\s+", 3);
        re = new RemoteException(parts[1], parts[2]);
        re = ((RemoteException)re).unwrapRemoteException(InvalidToken.class);
      }
{code}
Do you consider this fragile?

Disclaimer, In the patch I did here, it's not because there was existing code like quoted
above. Rather it's because the solution has its simplicity which we discussed earlier.

Thanks.


> distcp from insecure cluster (source) to secure cluster (destination) doesn't work via
webhdfs
> ----------------------------------------------------------------------------------------------
>
>                 Key: HDFS-6776
>                 URL: https://issues.apache.org/jira/browse/HDFS-6776
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.3.0, 2.5.0
>            Reporter: Yongjun Zhang
>            Assignee: Yongjun Zhang
>         Attachments: HDFS-6776.001.patch, HDFS-6776.002.patch, HDFS-6776.003.patch, HDFS-6776.004.patch,
HDFS-6776.004.patch, HDFS-6776.005.patch, HDFS-6776.006.NullToken.patch, HDFS-6776.006.NullToken.patch,
HDFS-6776.007.patch, HDFS-6776.008.patch, HDFS-6776.009.patch, HDFS-6776.010.patch, HDFS-6776.011.patch,
dummy-token-proxy.js
>
>
> Issuing distcp command at the secure cluster side, trying to copy stuff from insecure
cluster to secure cluster, and see the following problem:
> {code}
> hadoopuser@yjc5u-1 ~]$ hadoop distcp webhdfs://<insure-cluster>:<port>/tmp
hdfs://<sure-cluster>:8020/tmp/tmptgt
> 14/07/30 20:06:19 INFO tools.DistCp: Input Options: DistCpOptions{atomicCommit=false,
syncFolder=false, deleteMissing=false, ignoreFailures=false, maxMaps=20, sslConfigurationFile='null',
copyStrategy='uniformsize', sourceFileListing=null, sourcePaths=[webhdfs://<insecure-cluster>:<port>/tmp],
targetPath=hdfs://<secure-cluster>:8020/tmp/tmptgt, targetPathExists=true}
> 14/07/30 20:06:19 INFO client.RMProxy: Connecting to ResourceManager at <secure-clister>:8032
> 14/07/30 20:06:20 WARN ssl.FileBasedKeyStoresFactory: The property 'ssl.client.truststore.location'
has not been set, no TrustStore will be loaded
> 14/07/30 20:06:20 WARN security.UserGroupInformation: PriviledgedActionException as:hadoopuser@xyz.COM
(auth:KERBEROS) cause:java.io.IOException: Failed to get the token for hadoopuser, user=hadoopuser
> 14/07/30 20:06:20 WARN security.UserGroupInformation: PriviledgedActionException as:hadoopuser@xyz.COM
(auth:KERBEROS) cause:java.io.IOException: Failed to get the token for hadoopuser, user=hadoopuser
> 14/07/30 20:06:20 ERROR tools.DistCp: Exception encountered 
> java.io.IOException: Failed to get the token for hadoopuser, user=hadoopuser
> 	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> 	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
> 	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> 	at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
> 	at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:106)
> 	at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:95)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.toIOException(WebHdfsFileSystem.java:365)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.access$600(WebHdfsFileSystem.java:84)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.shouldRetry(WebHdfsFileSystem.java:618)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.runWithRetry(WebHdfsFileSystem.java:584)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.access$100(WebHdfsFileSystem.java:438)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner$1.run(WebHdfsFileSystem.java:466)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at javax.security.auth.Subject.doAs(Subject.java:415)
> 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1554)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.run(WebHdfsFileSystem.java:462)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.getDelegationToken(WebHdfsFileSystem.java:1132)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.getDelegationToken(WebHdfsFileSystem.java:218)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.getAuthParameters(WebHdfsFileSystem.java:403)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.toUrl(WebHdfsFileSystem.java:424)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractFsPathRunner.getUrl(WebHdfsFileSystem.java:640)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.runWithRetry(WebHdfsFileSystem.java:565)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.access$100(WebHdfsFileSystem.java:438)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner$1.run(WebHdfsFileSystem.java:466)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at javax.security.auth.Subject.doAs(Subject.java:415)
> 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1554)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.run(WebHdfsFileSystem.java:462)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.getHdfsFileStatus(WebHdfsFileSystem.java:781)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.getFileStatus(WebHdfsFileSystem.java:796)
> 	at org.apache.hadoop.fs.Globber.getFileStatus(Globber.java:57)
> 	at org.apache.hadoop.fs.Globber.glob(Globber.java:248)
> 	at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:1623)
> 	at org.apache.hadoop.tools.GlobbedCopyListing.doBuildListing(GlobbedCopyListing.java:77)
> 	at org.apache.hadoop.tools.CopyListing.buildListing(CopyListing.java:81)
> 	at org.apache.hadoop.tools.DistCp.createInputFileListing(DistCp.java:342)
> 	at org.apache.hadoop.tools.DistCp.execute(DistCp.java:154)
> 	at org.apache.hadoop.tools.DistCp.run(DistCp.java:121)
> 	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
> 	at org.apache.hadoop.tools.DistCp.main(DistCp.java:390)
> Caused by: org.apache.hadoop.ipc.RemoteException(java.io.IOException): Failed to get
the token for hadoopuser, user=hadoopuser
> 	at org.apache.hadoop.hdfs.web.JsonUtil.toRemoteException(JsonUtil.java:159)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.validateResponse(WebHdfsFileSystem.java:334)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.access$200(WebHdfsFileSystem.java:84)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.runWithRetry(WebHdfsFileSystem.java:570)
> 	... 30 more
> [hadoopuser@yjc5u-1 ~]$ 
> {code}



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