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https://issues.apache.org/jira/browse/HADOOP-14441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16019786#comment-16019786
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Rushabh S Shah commented on HADOOP-14441:
-----------------------------------------

[~jojochuang] We run sort of kms-ha with having 2 servers behind vip.
We don't face this issue. We have back-end zookeeper to sync the state between 
multiple kms servers.
Even if you have zookeeper enabled, what is the value of this config 
{{hadoop.kms.authentication.zk-dt-secret-manager.enable}} ?
Can you post some stack trace ?
I don't think the correct fix is to get delegation token from all the servers.
Even after the fix, the jobs can fail if one the servers went temporarily down 
and came back later and if the job was launched in between these time frame.

> 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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