Unable to create file using Pail DFS

Question

Newbie here. Trying to run the code from Nathan Marz's book Big Data DFS Datastore using Pail. What am I doing wrong? Trying to connect to an HDFS VM. Tried replacing hdfs with file. Any help appreciated.

public class AppTest
{
    private App app = new App();
    private String path = "hdfs:////192.168.0.101:8080/mypail";

    @Before
    public void init() throws IllegalArgumentException, IOException{
        FileSystem fs = FileSystem.get(new Configuration());
        fs.delete(new Path(path), true);
    }

    @Test public    void testAppAccess() throws IOException{
        Pail pail = Pail.create(path);
          TypedRecordOutputStream os = pail.openWrite();
          os.writeObject(new byte[] {1, 2, 3});
          os.writeObject(new byte[] {1, 2, 3, 4});
          os.writeObject(new byte[] {1, 2, 3, 4, 5});
          os.close();   
   }
}

Get an error -

java.lang.IllegalArgumentException: Wrong FS: hdfs:/192.168.0.101:8080/mypail, expected: file:///
    at org.apache.hadoop.fs.FileSystem.checkPath(FileSystem.java:645)
    at org.apache.hadoop.fs.RawLocalFileSystem.pathToFile(RawLocalFileSystem.java:80)
    at org.apache.hadoop.fs.RawLocalFileSystem.deprecatedGetFileStatus(RawLocalFileSystem.java:529)
    at org.apache.hadoop.fs.RawLocalFileSystem.getFileLinkStatusInternal(RawLocalFileSystem.java:747)

On replacing HDFS with file as file:///

java.io.IOException: Mkdirs failed to create file:/192.168.0.101:8080/mypail (exists=false, cwd=file:/Users/joshi/git/projectcsr/projectcsr)
    at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:442)
    at 

Answer 1

I came across the same problem and I solved it! You should add your core-site.xml to the hadoop Configuration object, something like this should work:

Configuration cfg = new Configuration();
Path core_site_path = new Path("path/to/your/core-site.xml");
cfg.addResource(core_site_path);
FileSystem fs = FileSystem.get(cfg);

I guess you could do the same also programmatically adding the property fs.defaultFS to the cfg object

Source: http://opensourceconnections.com/blog/2013/03/24/hdfs-debugging-wrong-fs-expected-file-exception/