docker-kafka-spark-poc

This project is intended to help data engineers quickly set up POCs using a Spark/Kafka infrastructure (or Spark/Kafka/MySQL) for several uses:

• If Spark/Kafka is a good fit to solve business challenges
• Learn how to work with the Spark/Kafka infrastructure

All of the pieces in this repo can be pieced together individually; however, when first assembling the structure it is very easy for one to spend more time focused on Docker setup, troubleshooting network issues, or figuring out exactly how to set up a producer, than it is to dive in to using Spark/Kafka themselves.

My hope is this project will help curious engineers jump right in to learning Spark and showing how it can add value to their team.

A HUGE credit for this goes to wurstmeister (https://github.com/wurstmeister) for his work on setting up Kafka + Zookeeper in a no-hastle way for Docker Compose.

Note: NOT to be used in production environments!

Overview

Components

• Zookeeper
  • https://zookeeper.apache.org/
  • An open source server for distributed coordination; Kafka runs on this and, in production environments, uses to ensure proper replication across instances
  • Most users of this project will not have to directly interact with Zookeeper
• Kafka
  • https://kafka.apache.org/
  • Open source distributed streaming platform
  • Users of this project will interact with Kafka in several ways:
    • Writing to Kafka using a simple producer program written in Python
    • Reading from Kafka using a simple consumer program written in Python
    • Reading from Kafka using Apache Spark
  • Kafka data is not persisted outside of the image, so each restart of the container will result in a new data set
• Zeppelin
  • https://zeppelin.apache.org/
  • Open source web-based computational notebook platform
  • Includes a Spark interpreter, making it very easy to write, test, and demo code
    • Because the interpreter is packaged with Zeppelin, you do not need to have a Spark cluster running locally on your machine, but that is configurable as well
  • Majority of interaction will be here
  • Configuration and notebooks are persisted outside of the image, to avoid tedious rework
  • A persistent directory for Spark outputs (such as Parquet) is provided
• MySQL (Optional)
  • Some teams will want to see that they can write outputs to a more traditional data system; an option is included with a MySQL container in the Docker network to make this easier
  • Data written to MySQL is persisted

Project Structure

• ./compose-files - Docker compose service definitions
• ./python-client
  • producer.py - Basic producer which sends test data to Kafka; for POC sub-in a custom data set
  • consumer.py - Basic consumer to quickly validate that data is flowing to Kafka
• setup_dir.sh - Setup local persistent directories which will be mounted
• requirements.txt - Python package requirements
• run_compose.sh - Run Zookeeper, Kafka, and Zeppelin in silent mode
• run_compose_mysql.sh - Run Zookeeper, Kafka, MySQL, and Zeppelin in silent mode.

Getting Started

Prerequisites

• docker-compose
• Python (Tested with 3.5; should be compatible with 2.7)
• virtualenv

Created on Ubuntu 16.04

Running Docker Compose

• Clone this repo locally:

git clone https://github.com/colemanja91/docker-kafka-spark-poc.git
cd ./docker-kafka-spark-poc

• Set up directories for mount volumes
  • sudo bash setup_dir.sh
  • If you want to change directory locations, you will need to update in the docker-compose files as well
  • This will also copy the default Zeppelin config file from this project, which has the necessary connection information for Kafka
• Run docker-compose
  • bash ./run_compose.sh
  • (with MySQL): bash ./run_compose_mysql.sh
• Verify that Zeppelin is running via browser:
  • localhost:8080

To kill the containers:

cd ./compose-files
docker-compose down --remove-orphans

Writing data to Kafka

Now that our Kafka instance is running, we need to send data to set up our POC.

• Set up a virtual environment:

virtualenv venv -p python3.5
source venv/bin/activate
pip install -r requirements.txt

• To send default test data:
  • python ./python-client/producer.py
  • This will randomly send one of three simple test records at intervals between 0.5-5 seconds
• A POC is often more helpful if using data you are familiar with; it may be helpful to load a JSON or CSV file of sample data to send

Reading data from Kafka

To ensure the data from the above producer is being captured by Kafka, we have a simple script which reads data from our test topic and prints to the console: python ./python-client/consumer.py

This is most helpful if trying to troubleshoot connection issues.

Basic Spark scripting

Artifacts

The artifact required to read from Kafka in Spark is included in the Zeppelin config: org.apache.spark:spark-sql-kafka-0-10_2.11:2.1.0 Also included is the MySQL JDBC driver: mysql:mysql-connector-java:5.1.38

Code snippets

Here are some basic code snippets for Spark (of course, it's more fun to figure them out on your own ;) ):

// Read in a data stream from Kafka

// Write Parquet table to our persistent volume