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Hadoop Docker

Pre-requisites

  • GNU Make >= 4 (or manually copy the commands from the Makefile recipes)

Quick Start

Build the local images

make

Download the purchases.txt file if not already

cd data
curl -L http://content.udacity-data.com/courses/ud617/purchases.txt.gz --output purchases.txt.gz
gzip -d purchases.txt.gz

To deploy an example HDFS cluster, run:

make up

Run example wordcount job:

make wordcount

Access the hadoop interfaces with the following URLs:

Manual run

Base manipulation

You can open a shell with direct access to hadoop as follows

make shell

In the opened shell, you can directly communicate with HDFS. Here's an example

# Clean up old data (if any)
hadoop fs -rm -r /output
rm -rf /data/output

# Copy the file to HDFS
hadoop fs -mkdir /input
hadoop fs -copyFromLocal /opt/hadoop-3.3.6/README.txt /input/

# Run the wordcount job
hadoop jar /data/WordCount.jar WordCount /input /output

# Copy the output to local
hadoop fs -copyToLocal /output /data/output

Mapper & Reducer Sample

This expects the purchases file to exist at ./data/purchases.txt. It is not included in the repository due due to its size.

# Clean up old data (if any)
hadoop fs -rm -r /myInput
hadoop fs -rm -r /myOutput

# Create the input directory in hadoop and copy the data there
hadoop fs -mkdir /myInput
hadoop fs -put /data/purchases.txt /myInput

# Run the map/reduce job (file option is local, not in hdfs)
mapred streaming \
    -file /data/sample/mapper.py    -mapper '/usr/bin/python3 mapper.py' \
    -file /data/sample/reducer.py   -reducer '/usr/bin/python3 reducer.py' \
    -input /myInput -output /myOutput

# Copy the output to local
hadoop fs -copyToLocal /myOutput /data/output

Configure Environment Variables

The configuration parameters can be specified in the hadoop.env file or as environmental variables for specific services (e.g. namenode, datanode etc.):

CORE_CONF_fs_defaultFS=hdfs://namenode:8020

CORE_CONF corresponds to core-site.xml. fs_defaultFS=hdfs://namenode:8020 will be transformed into:

<property>
    <name>fs.defaultFS</name>
    <value>hdfs://namenode:8020</value>
</property>

To define dash inside a configuration parameter, use triple underscore, such as YARNCONF_yarn_log**_aggregation**enable=true (yarn-site.xml):

<property>
    <name>yarn.log-aggregation-enable</name>
    <value>true</value>
</property>

The available configurations are:

  • /etc/hadoop/core-site.xml CORE_CONF
  • /etc/hadoop/hdfs-site.xml HDFS_CONF
  • /etc/hadoop/yarn-site.xml YARN_CONF
  • /etc/hadoop/httpfs-site.xml HTTPFS_CONF
  • /etc/hadoop/kms-site.xml KMS_CONF
  • /etc/hadoop/mapred-site.xml MAPRED_CONF

If you need to extend some other configuration file, refer to base/entrypoint.sh bash script.