How can I access S3 S3n from a local Hadoop 2 6 installation

Question

I am trying to reproduce an Amazon EMR cluster on my local machine. For that purpose, I have installed the latest stable version of Hadoop as of now - 2.6.0. Now I would like to access an S3 bucket, as I do inside the EMR cluster.

I have added the aws credentials in core-site.xml:

<property>
  <name>fs.s3.awsAccessKeyId</name>
  <value>some id</value>
</property>

<property>
  <name>fs.s3n.awsAccessKeyId</name>
  <value>some id</value>
</property>

<property>
  <name>fs.s3.awsSecretAccessKey</name>
  <value>some key</value>
</property>

<property>
  <name>fs.s3n.awsSecretAccessKey</name>
  <value>some key</value>
</property>

Note: Since there are some slashes on the key, I have escaped them with %2F

If I try to list the contents of the bucket:

hadoop fs -ls s3://some-url/bucket/

I get this error:

ls: No FileSystem for scheme: s3

I edited core-site.xml again, and added information related to the fs:

<property>
  <name>fs.s3.impl</name>
  <value>org.apache.hadoop.fs.s3.S3FileSystem</value>
</property>

<property>
  <name>fs.s3n.impl</name>
  <value>org.apache.hadoop.fs.s3native.NativeS3FileSystem</value>
</property>

This time I get a different error:

-ls: Fatal internal error
java.lang.RuntimeException: java.lang.ClassNotFoundException: Class org.apache.hadoop.fs.s3.S3FileSystem not found
        at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2074)
        at org.apache.hadoop.fs.FileSystem.getFileSystemClass(FileSystem.java:2578)
        at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2591)

Somehow I suspect the Yarn distribution does not have the necessary jars to be able to read S3, but I have no idea where to get those.

Can someone help me out with this?

Answer 1

For some reason, the jar hadoop-aws-[version].jar which contains the implementation to NativeS3FileSystem is not present in the classpath of hadoop by default in the version 2.6 & 2.7. So, try and add it to the classpath by adding the following line in hadoop-env.sh which is located in $HADOOP_HOME/etc/hadoop/hadoop-env.sh:

export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:$HADOOP_HOME/share/hadoop/tools/lib/*

Assuming you are using Apache Hadoop 2.6 or 2.7

By the way, you could check the classpath of Hadoop using:

bin/hadoop classpath