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https://issues.apache.org/jira/browse/HADOOP-13988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15837106#comment-15837106
 ] 

Xiaoyu Yao commented on HADOOP-13988:
-------------------------------------

Thanks [~jnp] and [~lmccay] for the review. 

bq. Knox never interacts directly with KMS and neither does the Knox enduser.

Hadoop proxy user does not recommend using delegation token to proxy another 
user. Oozie for example uses a kerberos to proxy its end user. That's also the 
expected usage from HADOOP-13749. 

Knox can either uses UGI with kerberos to create proxy user for its end user, 
or impersonate end user to get KMS-DT and add it to the end user's UGI if the 
file accessed is in encryption zone.

> KMSClientProvider does not work with WebHDFS and Apache Knox w/ProxyUser
> ------------------------------------------------------------------------
>
>                 Key: HADOOP-13988
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13988
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: common, kms
>    Affects Versions: 2.8.0, 2.7.3
>         Environment: HDP 2.5.3.0 
> WebHDFSUser --> Knox --> HA NameNodes(WebHDFS) --> DataNodes
>            Reporter: Greg Senia
>            Assignee: Xiaoyu Yao
>         Attachments: HADOOP-13988.01.patch, HADOOP-13988.02.patch, 
> HADOOP-13988.patch, HADOOP-13988.patch
>
>
> After upgrading to HDP 2.5.3.0 noticed that all of the KMSClientProvider 
> issues have not been resolved. We put a test build together and applied 
> HADOOP-13558 and HADOOP-13749 these two fixes did still not solve the issue 
> with requests coming from WebHDFS through to Knox to a TDE zone.
> So we added some debug to our build and determined effectively what is 
> happening here is a double proxy situation which does not seem to work. So we 
> propose the following fix in getActualUgi Method:
> {noformat}
>      }
>      // Use current user by default
>      UserGroupInformation actualUgi = currentUgi;
>      if (currentUgi.getRealUser() != null) {
>        // Use real user for proxy user
>        if (LOG.isDebugEnabled()) {
>          LOG.debug("using RealUser for proxyUser);
>       }
>        actualUgi = currentUgi.getRealUser();
>        if (getDoAsUser() != null) {
>                 if (LOG.isDebugEnabled()) {
>               LOG.debug("doAsUser exists");
>               LOG.debug("currentUGI realUser shortName: {}", 
> currentUgi.getRealUser().getShortUserName());
>               LOG.debug("processUGI loginUser shortName: {}", 
> UserGroupInformation.getLoginUser().getShortUserName());
>           }
>         if (currentUgi.getRealUser().getShortUserName() != 
> UserGroupInformation.getLoginUser().getShortUserName()) {
>                 if (LOG.isDebugEnabled()) {
>                       LOG.debug("currentUGI.realUser does not match 
> UGI.processUser);
>                 }
>                 actualUgi = UserGroupInformation.getLoginUser();
>                 if (LOG.isDebugEnabled()) {
>                       LOG.debug("LoginUser for Proxy: {}", 
> actualUgi.getLoginUser());
>                 }
>         }
>        }
>       
>      } else if (!currentUgiContainsKmsDt() &&
>          !currentUgi.hasKerberosCredentials()) {
>        // Use login user for user that does not have either
>        // Kerberos credential or KMS delegation token for KMS operations
>        if (LOG.isDebugEnabled()) {
>          LOG.debug("using loginUser no KMS Delegation Token no Kerberos 
> Credentials");
>       }
>        actualUgi = currentUgi.getLoginUser();
>      }
>      return actualUgi;
>    }
> {noformat}



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