Installing and running Apache Kafka on Linux system

Apache Kafka 

Apache Kafka is publishing-subscribing messaging rethought as a distributed commit log.

Fast

A single Kafka broker can handle hundreds of megabytes of reads and writes per second from thousands of clients.

Scalable

Kafka is designed to allow a single cluster to serve as the central data backbone for a large organization. It can be elastically and transparently expanded without downtime. Data streams are partitioned and spread over a cluster of machines to allow data streams larger than the capability of any single machine and to allow clusters of coordinated consumers

Durable

Messages are persisted on disk and replicated within the cluster to prevent data loss. Each broker can handle terabytes of messages without performance impact.

Distributed by Design

Kafka has a modern cluster-centric design that offers strong durability and fault-tolerance guarantees.

Working with Kafka:

This assumes you are starting fresh and have no existing Kafka or ZooKeeper data. See http://kafka.apache.org/documentation.html#quickstart for more details.

Install Java

sudo apt-get install python-software-properties

sudo add-apt-repository ppa:webupd8team/java

sudo apt-get update

sudo apt-get install oracle-java8-installer

Download Kafka

Download latest version from here. If link is not clickable then go to below given url and download latest version of Kafka.

http://kafka.apache.org/downloads.html

I am installing Kafka 2.11-0.10.0.0

cd /usr/src/

wget http://mirror.stjschools.org/public/apache/kafka/0.10.0.0/kafka_2.11-0.10.0.0.tgz

tar -xzf kafka_2.9.2-0.8.1.tgz

cd kafka_2.9.2-0.8.1

Running Kafka

Kafka uses Zookeeper to provide a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.

To Start Zookeeper

bin/zookeeper-server-start.sh config/zookeeper.properties

To Start Kafka

bin/kafka-server-start.sh config/server.properties

Create a Topic

This will create a topic called Test

bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test

This topic can then be view using:

bin/kafka-topics.sh --list --zookeeper localhost:2181

Alternatively, instead of manually creating topics you can also configure your brokers to auto-create topics when a non-existent topic is published to.

Create Messages - Producer

Kafka comes with a command line client that will take input from a file or from standard input and send it out as messages to the Kafka cluster. By default each line will be sent as a separate message.

Run the producer and then type a few messages into the console to send to the server.

bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test

This is a message

This is another message

And so is this

Read Messages - Consumer

Kafka also has a command line consumer that will dump out messages to standard output.

bin/kafka-console-consumer.sh --zookeeper localhost:2181 --topic test --from-beginning

This is a message

This is another message

And so is this

Setting up a multi-broker cluster

Kafka can run with multiple brokers. Let’s make it a three broker cluster

cp config/server.properties config/server-1.properties

cp config/server.properties config/server-2.properties

Now edit these new files and set the following properties:

config/server-1.properties:

    broker.id=1

    port=9093

    log.dir=/tmp/kafka-logs-1

config/server-2.properties:

    broker.id=2

    port=9094

    log.dir=/tmp/kafka-logs-2

Each kafka instance has a separate port (default is 9092).

The broker.id property is the unique and permanent name of each node in the cluster. We have to override the port and log directory only because we are running these all on the same machine and we want to keep the brokers from all trying to register on the same port or overwrite each others data.

We already have Zookeeper and our single node started, so we just need to start the two new nodes:

bin/kafka-server-start.sh config/server-1.properties &

bin/kafka-server-start.sh config/server-2.properties &

Now create a new topic with a replication factor of three

bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 3 --partitions 1 --topic my-replicated-topic

How to see what the broker is doing

bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic my-replicated-topic

This returns:

Topic:my-replicated-topic   PartitionCount:1    ReplicationFactor:3 Configs:

        Topic: my-replicated-topic  Partition: 0    Leader: 2   Replicas: 2,1,0 Isr: 2,1,0

Here is an explanation of output. The first line gives a summary of all the partitions, each additional line gives information about one partition. Since we have only two partitions for this topic there are only two lines.

*<strong>leader</strong> is the node responsible for all reads and writes for the given partition. Each node will be the leader for a randomly selected portion of the partitions.

*<strong>replicas</strong> is the list of nodes that replicate the log for this partition regardless of whether they are the leader or even if they are currently alive.

*<strong>isr</strong> is the set of "in-sync" replicas. This is the subset of the replicas list that is currently alive and caught-up to the leader.

We can run the same command on the original topic we created to see where it is:

bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic test

This returns:

Topic:test  PartitionCount:1    ReplicationFactor:1 Configs:

Topic: test Partition: 0    Leader: 0   Replicas: 0 Isr: 0

The original topic has no replicas and is on server 0, which was the only server in our cluster when we created it.