[jira] [Work logged] (CRUNCH-677) Support passing FileSystem to File Sources and Targets

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CRUNCH-677?focusedWorklogId=201490&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-201490 ]

ASF GitHub Bot logged work on CRUNCH-677:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 20/Feb/19 18:05
            Start Date: 20/Feb/19 18:05
    Worklog Time Spent: 10m 
      Work Description: ben-roling commented on pull request #19: CRUNCH-677 Source and Target accept FileSystem
URL: https://github.com/apache/crunch/pull/19
 
 
   The change to Source, Target, and SourceTarget obviously breaks compatibility for implementors of these interfaces as we're still building against Java 7 so I can't provide a default implementation for these new methods.
   
   Also, there is an expectation that Target implementations will need to update the asSourceTarget() method to copy the FileSystem along.
 
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Issue Time Tracking
-------------------

            Worklog Id:     (was: 201490)
            Time Spent: 10m
    Remaining Estimate: 0h

> Support passing FileSystem to File Sources and Targets
> ------------------------------------------------------
>
>                 Key: CRUNCH-677
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-677
>             Project: Crunch
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Ben Roling
>            Assignee: Josh Wills
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> We'd like to pass a FileSystem instance to File Sources and Targets to fully qualify the Path.  Without the FileSystem, the Pipeline doesn't necessarily have enough information to understand the Path.  In particular, when the Path is an HA HDFS path like "hdfs://my-cluster/data", the Pipeline might not have the [configuration|https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithNFS.html#Configuration_details] to resolve "hdfs://my-cluster".
> While it is in some cases possible to seed the Pipeline configuration with all the HDFS properties necessary to communicate with any HDFS HA cluster the Pipeline might talk to, it can be awkward and/or difficult to do this in all cases.  We have cases where we'd like not to have to know all of the clusters upfront.
> With the proposed change, code like the following is possible, where {{readFileSystem}} and {{writeFileSystem}} are external FileSystems synthesized from Configuration completely separate from that used to construct the Pipeline itself:
> {code}
> Configuration emptyConfiguration = new Configuration(false);
> Pipeline pipeline = new MRPipeline(getClass(), emptyConfiguration);
> FileSystem readFileSystem = ...;
> PCollection<String> data = pipeline.read(From.textFile("hdfs://my-cluster-1/data", readFileSystem));
> FileSystem writeFileSystem = ...;
> pipeline.write(data, To.textFile("hdfs://my-cluster-2/output", writeFileSystem));
> {code}
> Note: the hdfs://my-cluster-1 and hdfs://my-cluster-2 parts of the paths would not strictly need to be included as they would be implied by the FileSystem instances passed in the calls.  As such the paths could simply be passed as "/data" and "/output" with equivalent behavior.



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