Custom Source in Flume

Flume provides a way where you can write your own source.As we know that there are default source type available in flume like exec,spoolDir,Tiwtter. Here I have a tried small demonstration for custom flume source.In this example I have written MySource java class which will read single line from input and concatenate them as output and it will pass it to channel.

Example:

Sample Input File :

20

50

50

04

17

59

18

43

28

58

27

81

Sample Output File :

 

20

2050

205050

20505004

2050500417

205050041759

20505004175918

2050500417591843

205050041759184328

20505004175918432858

First line is concatenated with other and process continues in this way.

Here is my Java Code.

MySource.Java

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.nio.charset.Charset;

import org.apache.flume.Context;

import org.apache.flume.Event;

import org.apache.flume.EventDeliveryException;

import org.apache.flume.PollableSource;

import org.apache.flume.conf.Configurable;

import org.apache.flume.event.EventBuilder;

import org.apache.flume.source.AbstractSource;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class MySource extends AbstractSource implements Configurable, PollableSource {

  private static final Logger logger = LoggerFactory.getLogger(MySource.class);

  private String myProp;

  BufferedReader br;

  Thread tailThread;

  @Override

  public void configure(Context context) {

    String myProp = context.getString("filepath", "defaultValue");

    logger.info("Path Property==============>" + myProp);

    this.myProp = myProp;

  }

  @Override

  public void start() {

 ConcatRunner t = new ConcatRunner();

 tailThread = new Thread(t);

 tailThread.start();

}

  @Override

  public void stop () {

  }

@Override

public Status process() throws EventDeliveryException {

// TODO Auto-generated method stub

return null;

}

private class ConcatRunner implements Runnable {

    @Override

    public void run() {

   Event e;

      String sCurrentLine;

   String finalFlumeString = "";

   

   try

     {

      br = new BufferedReader(new FileReader(myProp));

     while ((sCurrentLine = br.readLine()) != null) {

  System.out.println(sCurrentLine);

  finalFlumeString = finalFlumeString +  sCurrentLine ; // Concatinating String

  e = EventBuilder.withBody(finalFlumeString,

               Charset.forName("UTF-8"));

  getChannelProcessor().processEvent(e);

  Thread.sleep(3000);

  }

     }

     catch(Exception ex){

      System.out.println("Exception in Reading File" + ex.getMessage());      

     }

     try {

  if (br != null)br.close();

  } catch (IOException ex) {

  ex.printStackTrace();

  }

            }

} //ConcatRunner Over 

}

FlumeConfig.conf File :

a1.sources = r1

a1.channels = c1

a1.sinks = k1

#source

a1.sources.r1.type = MySource

a1.sources.r1.restart = true

a1.sources.r1.filepath = /root/input.txt

#sink

a1.sinks.k1.type = hdfs

a1.sinks.k1.hdfs.path = /flume/events/

a1.sinks.k1.hdfs.filePrefix = events-

a1.sinks.k1.hdfs.round = true

a1.sinks.k1.hdfs.fileType = DataStream

#channel

a1.channels.c1.type = memory

#connect

a1.sources.r1.channels = c1

a1.sinks.k1.channel = c1

Before you proceed for running job , create Jar of your  java project and place it into lib folder of Flume(/usr/lib/flume/lib).

Once your are done with above then fire following command form shell.

flume-ng agent -n a1  -f FlumeConfig.conf

Output of Job:

<This Part is optional>

Apart from above , I have created a shell script which will generate input for you.This script expects two parameter 1. No of Rows 2. Delay Time for generating next row, I have delay time as 2 sec. You can change it as per your need.Here is a sample shell script

#!/bin/sh

echo "Please enter the size in terms of rows you want to generate the random file data"

read rows

#rows=$1

echo "Please enter the delay time needed in between the writing of the rows"

read delayTime

#Delete the tmp & generatedRandomDataFile files if they already exist

rm -f tmp

rm -f generatedRandomDataFile

start=$(date +%s)

for i in $(seq $rows)

do

tr -dc 0-9 < /dev/urandom | head -c 2 > tmp

gawk '$1=$1' tmp >> generatedRandomDataFile

sleep $delayTime

done

end=$(date +%s)

DIFF=$(( $end - $start ))

echo "File generated is `pwd`/generatedRandomDataFile"

echo "The file generation took $DIFF seconds"

Here is sample output of shell script.

Reference :

https://flume.apache.org/FlumeDeveloperGuide.html 

Let me know for any suggestion.

Cheers!!!!!!!!!!!!!!!