kafka-docker

Dockerfile for Apache Kafka

The image is available directly from https://registry.hub.docker.com/

##Pre-Requisites

• install docker-compose https://docs.docker.com/compose/install/

##Usage

Start a cluster:

• docker-compose up -d

Add more brokers:

• docker-compose scale kafka=3

Destroy a cluster:

• docker-compose stop

Commands

You can enter a command line through docker-compose:

    docker-compose run bash

You can then run commands, with these variables:

• $KAFKA_HOME is the Kafka installation directory.
• zookeeper:2181 is the address for accessing zookeeper
• kafka:9092 is the address for accessing kafka

For example, you can create some topics:

    $KAFKA_HOME/bin/kafka-topics.sh --create --topic test --partitions 4 --zookeeper zookeeper:2181 --replication-factor 1
    $KAFKA_HOME/bin/kafka-topics.sh --list --zookeeper zookeeper:2181

Or send some messages:

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

And read those messages:

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

Kafka Manager

Kafka Manager is included with this compose script. It can be accessed at [http://localhost:9000].

You might have to manually tell the manager about your cluster. To do so, just use a zookeeper address of zookeeper:2181.

##Note

The default docker-compose.yml should be seen as a starting point. By default each broker will get a new port number and broker id on restart. Depending on your use case this might not be desirable. If you need to use specific ports and broker ids, modify the docker-compose configuration accordingly, e.g. docker-compose-single-broker.yml:

• docker-compose -f docker-compose-single-broker.yml up

##Broker IDs

If you don't specify a broker id in your docker-compose file, it will automatically be generated (see https://issues.apache.org/jira/browse/KAFKA-1070. This allows scaling up and down. In this case it is recommended to use the --no-recreate option of docker-compose to ensure that containers are not re-created and thus keep their names and ids.

Customization

• modify the KAFKA_ADVERTISED_HOST_NAME in docker-compose.yml to match your docker host IP (Note: Do not use localhost or 127.0.0.1 as the host ip if you want to run multiple brokers.)
• if you want to customise any Kafka parameters, simply add them as environment variables in docker-compose.yml, e.g. in order to increase the message.max.bytes parameter set the environment to KAFKA_MESSAGE_MAX_BYTES: 2000000. To turn off automatic topic creation set KAFKA_AUTO_CREATE_TOPICS_ENABLE: 'false'

##Automatically create topics

If you want to have kafka-docker automatically create topics in Kafka during creation, a KAFKA_CREATE_TOPICS environment variable can be added in docker-compose.yml.

Here is an example snippet from docker-compose.yml:

    environment:
      KAFKA_CREATE_TOPICS: "Topic1:1:3,Topic2:1:1"

Topic 1 will have 1 partition and 3 replicas, Topic 2 will have 1 partition and 1 replica.

##Advertised hostname

You can configure the advertised hostname in different ways

1. explicitly, using KAFKA_ADVERTISED_HOST_NAME
2. via a command, using HOSTNAME_COMMAND, e.g. HOSTNAME_COMMAND: "route -n | awk '/UG[ \t]/{print $$2}'"

When using commands, make sure you review the "Variable Substitution" section in https://docs.docker.com/compose/compose-file/

If KAFKA_ADVERTISED_HOST_NAME is specified, it takes presendence over HOSTNAME_COMMAND

For AWS deployment, you can use the Metadata service to get the container host's IP:

HOSTNAME_COMMAND=wget -t3 -T2 -qO-  http://169.254.169.254/latest/meta-data/local-ipv4

Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

##Tutorial

http://wurstmeister.github.io/kafka-docker/