Use Spark to list all files in a Hadoop HDFS directory? - scala

Question

I want to loop through all text files in a Hadoop dir and count all the occurrences of the word "error". Is there a way to do a hadoop fs -ls /users/ubuntu/ to list all the files in a dir with the Apache Spark Scala API?
From the given first example, the spark context seems to only access files individually through something like:
val file = spark.textFile("hdfs://target_load_file.txt")
In my problem, I do not know how many nor the names of the files in the HDFS folder beforehand. Looked at the spark context docs but couldn't find this kind of functionality.

Answer 1

You can use a wildcard:
val errorCount = sc.textFile("hdfs://some-directory/*")
.flatMap(_.split(" ")).filter(_ == "error").count

Answer 2

import org.apache.hadoop.fs.{FileSystem, FileUtil, Path}
import scala.collection.mutable.Stack
val fs = FileSystem.get( sc.hadoopConfiguration )
var dirs = Stack[String]()
val files = scala.collection.mutable.ListBuffer.empty[String]
val fs = FileSystem.get(sc.hadoopConfiguration)
dirs.push("/user/username/")
while(!dirs.isEmpty){
val status = fs.listStatus(new Path(dirs.pop()))
status.foreach(x=> if(x.isDirectory) dirs.push(x.getPath.toString) else
files+= x.getPath.toString)
}
files.foreach(println)

Answer 3

For a local installation, (the hdfs default path fs.defaultFS can be found by reading /etc/hadoop/core.xml):
For instance,
import org.apache.hadoop.fs.{FileSystem, Path}
val conf = sc.hadoopConfiguration
conf.set("fs.defaultFS", "hdfs://localhost:9000")
val hdfs: org.apache.hadoop.fs.FileSystem = org.apache.hadoop.fs.FileSystem.get(conf)
val fileStatus = hdfs.listStatus(new Path("hdfs://localhost:9000/foldername/"))
val fileList = fileStatus.map(x => x.getPath.toString)
fileList.foreach(println)