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https://issues.apache.org/jira/browse/HADOOP-14441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16021628#comment-16021628
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Wei-Chiu Chuang commented on HADOOP-14441:
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[~shahrs87] thanks for your comments and your effort in creating the patch.
I've been thinking about alternative way to fix it, but they all turn out to be
either incompatible (adding extra parameters to public API), or unable to allow
a client to get delegation tokens from multiple KMS clusters. If your patch is
incompatible, would you mind to move over to HADOOP-14445 and use this one for
a short term fix?
Thanks
> LoadBalancingKMSClientProvider#addDelegationTokens should add delegation
> tokens from all KMS instances
> ------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-14441
> URL: https://issues.apache.org/jira/browse/HADOOP-14441
> Project: Hadoop Common
> Issue Type: Bug
> Components: kms
> Affects Versions: 2.7.0
> Environment: CDH5.7.4, Kerberized, SSL, KMS-HA, at rest encryption
> Reporter: Wei-Chiu Chuang
> Assignee: Wei-Chiu Chuang
> Attachments: HADOOP-14441.001.patch, HADOOP-14441.002.patch,
> HADOOP-14441.003.patch
>
>
> LoadBalancingKMSClientProvider only gets delegation token from one KMS
> instance, in a round-robin fashion. This is arguably a bug, as JavaDoc for
> {{KeyProviderDelegationTokenExtension#addDelegationTokens}} states:
> {quote}
> /**
> * The implementer of this class will take a renewer and add all
> * delegation tokens associated with the renewer to the
> * <code>Credentials</code> object if it is not already present,
> ...
> **/
> {quote}
> This bug doesn't pop up very often, because HDFS clients such as MapReduce
> unintentionally calls {{FileSystem#addDelegationTokens}} multiple times.
> We have a custom client that accesses HDFS/KMS-HA using delegation token, and
> we were puzzled why it always throws "Failed to find any Kerberos tgt"
> exceptions talking to one KMS but not the other. Turns out that client
> couldn't talk to the KMS because {{FileSystem#addDelegationTokens}} only gets
> one KMS delegation token at a time.
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