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https://issues.apache.org/jira/browse/HDFS-14017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16678570#comment-16678570
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Erik Krogen commented on HDFS-14017:
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Interesting... I see the issue now. I did not notice previously that you were
relying on the default FS via {{DFSUtilClient.getNNAddress(conf)}}. Actually,
IIRC, even in a non-federated environment, this won't work if a user specifies
a non-default FS.
You should be able to extract the correct value from
{{dfs.namenode.rpc-address.<nnID>}}, which contains the VIP, at least in our
configurations (I can't seem to find {{IPFailoverPP}} configuration documented
anywhere... the [HA
documentation|https://hadoop.apache.org/docs/r3.1.1/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithQJM.html]
doesn't even mention it as a valid proxy provider). You can then match this
against the URI provided to the constructor to determine what name service this
proxy provider belongs to, and use that to determine the correct physical
hostnames.
> ObserverReadProxyProviderWithIPFailover should work with HA configuration
> -------------------------------------------------------------------------
>
> Key: HDFS-14017
> URL: https://issues.apache.org/jira/browse/HDFS-14017
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Chen Liang
> Assignee: Chen Liang
> Priority: Major
> Attachments: HDFS-14017-HDFS-12943.001.patch,
> HDFS-14017-HDFS-12943.002.patch, HDFS-14017-HDFS-12943.003.patch,
> HDFS-14017-HDFS-12943.004.patch, HDFS-14017-HDFS-12943.005.patch
>
>
> Currently {{ObserverReadProxyProviderWithIPFailover}} extends
> {{ObserverReadProxyProvider}}, and the only difference is changing the proxy
> factory to use {{IPFailoverProxyProvider}}. However this is not enough
> because when calling constructor of {{ObserverReadProxyProvider}} in
> super(...), the follow line:
> {code:java}
> nameNodeProxies = getProxyAddresses(uri,
> HdfsClientConfigKeys.DFS_NAMENODE_RPC_ADDRESS_KEY);
> {code}
> will try to resolve the all configured NN addresses to do configured
> failover. But in the case of IPFailover, this does not really apply.
>
> A second issue closely related is about delegation token. For example, in
> current IPFailover setup, say we have a virtual host nn.xyz.com, which points
> to either of two physical nodes nn1.xyz.com or nn2.xyz.com. In current HDFS,
> there is always only one DT being exchanged, which has hostname nn.xyz.com.
> Server only issues this DT, and client only knows the host nn.xyz.com, so all
> is good. But in Observer read, even with IPFailover, the client will no
> longer contacting nn.xyz.com, but will actively reaching to nn1.xyz.com and
> nn2.xyz.com. During this process, current code will look for DT associated
> with hostname nn1.xyz.com or nn2.xyz.com, which is different from the DT
> given by NN. causing Token authentication to fail. This happens in
> {{AbstractDelegationTokenSelector#selectToken}}. New IPFailover proxy
> provider will need to resolve this as well.
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