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https://issues.apache.org/jira/browse/HDFS-14017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16680370#comment-16680370
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Konstantin Shvachko commented on HDFS-14017:
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The patch looks good. Really liked all changes are concentrated inside
ORPPWithIPF class. Minor things:
# Log messages should avoid string concatenation for performance, e.g.:
{{LOG.debug("Adding new proxy with address {}", isa)}}
# JavaDoc for ORPPWithIPF class should be revised. Particularly it should
explicitly say how address for IPFailover is configured, and that the rest of
the namenodes are setup as in regular HA config. Let's also include an example
of a config.
# JavaDoc for the constructor is confusing.
# We also need some tests for ORPPWithIPF. I am fine doing it in a followup
jira.
> 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,
> HDFS-14017-HDFS-12943.006.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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