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From: Parth-Brahmbhatt <git@git.apache.org>
To: dev@storm.incubator.apache.org
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Subject: [GitHub] incubator-storm pull request: STORM-346: added AutoHDFS
 class that...
Content-Type: text/plain
Message-Id: <20140718201429.A2DEA94F20D@tyr.zones.apache.org>
Date: Fri, 18 Jul 2014 20:14:29 +0000 (UTC)

Github user Parth-Brahmbhatt commented on the pull request:

    https://github.com/apache/incubator-storm/pull/190#issuecomment-49474731
  
    Here is what I have so far:
    
    User can specify AutoHDFS.java as "nimbus.credential.renewers.classes" and AutoHDFS will only implement ICredentialsRenewer. In the prepare phase of AutoHDFS.java, which should be called on nimbus startup, we can get the HDFS credentials. However, I don't think the topology submitter user will be available at that time so we will not be able to get the token on behalf of the user but only as nimbus which I feel is unacceptable. 
    
    In order to actually get the credentials as topology submitter user, we either need a new Interface that will run on nimbus when a topology is submitted as part of submitTopologyWithOpts implementation or we can add getCredentialForUser(Map conf) method to ICredentialsRenewer interface and call that as part of submitTopologyWithOpts. I personally prefer not to pollute the ICredentialsRenewer interface. Let me know if you have better alternatives or prefer one over another.
    
    I have one last question. The ICredentialsRenewer implementations seems to be loaded by reading "nimbus.credential.renewers.classes" config at startup by nimbus. This means the users who have a running nimbus and wants to use AutoHDFS or any other implementation of ICredentialsRenewer will have to change the config and restart the nimbus. Is that acceptable? 
    

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