[ 
https://issues.apache.org/jira/browse/BEAM-1491?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

yangping wu updated BEAM-1491:
------------------------------
    Description: 
Currently, if we want to read file store on HDFS, we will do it as follow:
{code} PCollection<KV<LongWritable, Text>> resultCollection = 
p.apply(HDFSFileSource.readFrom(
                "hdfs://hadoopserver:8020/tmp/data.txt",
                TextInputFormat.class, LongWritable.class, Text.class));
{code}
As we have seen above, we must be set {{hdfs://hadoopserver:8020}} in the file 
path, and we cann't set any variables when read file, because in 
[HDFSFileSource.java|https://github.com/apache/beam/blob/master/sdks/java/io/hdfs/src/main/java/org/apache/beam/sdk/io/hdfs/HDFSFileSource.java#L310]
 we initialize {{job}} instance as follow:
{code}
this.job = Job.getInstance();
{code}
we should initialize {{job}} instance by configure:
{code}
this.job = Job.getInstance(conf);
{code}
where {{conf}} is instance of {{Configuration}}, and we initialize {{conf}} by 
reading {{HADOOP_CONF_DIR}}({{YARN_CONF_DIR}}) environmen variable,then we can 
read HDFS file like this:
{code} PCollection<KV<LongWritable, Text>> resultCollection = 
p.apply(HDFSFileSource.readFrom(
                "/tmp/data.txt",
                TextInputFormat.class, LongWritable.class, Text.class));
{code}
note we don't specify {{hdfs://hadoopserver:8020}} prefix, because the program 
read it from  {{HADOOP_CONF_DIR}}({{YARN_CONF_DIR}}) environmen.

  was:
Currently, if we want to read file store on HDFS, we will do it as follow:
{code} PCollection<KV<LongWritable, Text>> resultCollection = 
p.apply(HDFSFileSource.readFrom(
                "hdfs://hadoopserver:8020/tmp/data.txt",
                TextInputFormat.class, LongWritable.class, Text.class));
{code}
As we have seen above, we must be set {{hdfs://hadoopserver:8020}} in the file 
path, and we cann't set any variables when read file, because in 
[HDFSFileSource.java|https://github.com/apache/beam/blob/master/sdks/java/io/hdfs/src/main/java/org/apache/beam/sdk/io/hdfs/HDFSFileSource.java#L310]
 we initialize {{job}} instance as follow:
{code}
this.job = Job.getInstance();
{code}
we should initialize {{job}} instance by configure:
{code}
this.job = Job.getInstance(conf);
{code}
where {{conf}} is instance of {{Configuration}}, and we initialize {{conf}} by 
reading {{HADOOP_CONF}}({{YARN_CONF}}) environmen variable,then we can read 
HDFS file like this:
{code} PCollection<KV<LongWritable, Text>> resultCollection = 
p.apply(HDFSFileSource.readFrom(
                "/tmp/data.txt",
                TextInputFormat.class, LongWritable.class, Text.class));
{code}
note we don't specify {{hdfs://hadoopserver:8020}} prefix, because the program 
read it from  {{HADOOP_CONF}}({{YARN_CONF}}) environmen.


> HDFSFileSource should be able to read the HADOOP_CONF_DIR(YARN_CONF_DIR) 
> environmen variable
> --------------------------------------------------------------------------------------------
>
>                 Key: BEAM-1491
>                 URL: https://issues.apache.org/jira/browse/BEAM-1491
>             Project: Beam
>          Issue Type: Improvement
>          Components: sdk-java-core
>    Affects Versions: 0.5.0
>            Reporter: yangping wu
>            Assignee: Jean-Baptiste Onofré
>
> Currently, if we want to read file store on HDFS, we will do it as follow:
> {code} PCollection<KV<LongWritable, Text>> resultCollection = 
> p.apply(HDFSFileSource.readFrom(
>                 "hdfs://hadoopserver:8020/tmp/data.txt",
>                 TextInputFormat.class, LongWritable.class, Text.class));
> {code}
> As we have seen above, we must be set {{hdfs://hadoopserver:8020}} in the 
> file path, and we cann't set any variables when read file, because in 
> [HDFSFileSource.java|https://github.com/apache/beam/blob/master/sdks/java/io/hdfs/src/main/java/org/apache/beam/sdk/io/hdfs/HDFSFileSource.java#L310]
>  we initialize {{job}} instance as follow:
> {code}
> this.job = Job.getInstance();
> {code}
> we should initialize {{job}} instance by configure:
> {code}
> this.job = Job.getInstance(conf);
> {code}
> where {{conf}} is instance of {{Configuration}}, and we initialize {{conf}} 
> by reading {{HADOOP_CONF_DIR}}({{YARN_CONF_DIR}}) environmen variable,then we 
> can read HDFS file like this:
> {code} PCollection<KV<LongWritable, Text>> resultCollection = 
> p.apply(HDFSFileSource.readFrom(
>                 "/tmp/data.txt",
>                 TextInputFormat.class, LongWritable.class, Text.class));
> {code}
> note we don't specify {{hdfs://hadoopserver:8020}} prefix, because the 
> program read it from  {{HADOOP_CONF_DIR}}({{YARN_CONF_DIR}}) environmen.



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