These images are intended to be configuration-compatible with the confluentinc/cp-zookeeper and confluentinc/cp-kafka images; however, unlike those images, these are built as multi-architecture images for both amd64 and arm64 in order to be compatible with Mac OS on M1 Apple Silicon and the usual x86 hardware.

Zookeeper

This image is primarily intended to support itzg/kafka while KRaft support is being finalized.

Environment variables

Any of the configuration parameters can be set by translating the property name from camelCase to SCREAMING_SNAKE_CASE and prefixing with "ZOOKEEPER_", such as ZOOKEEPER_CLIENT_PORT.

The following variables are pre-declared:

• ZOOKEEPER_CLIENT_PORT = 2181
• ZOOKEEPER_DATA_DIR = /var/lib/zookeeper/data
• ZOOKEEPER_TICK_TIME = 1000
• SERVER_JVMFLAGS = -Xmx256m

Ports

• 2181

Volumes

• /var/lib/zookeeper/data

Healthcheck

The image comes with a health check script, /init/healthcheck, that is pre-configured for non-Kubernetes environments.

Kafka

Environment variables

Any of the broker configuration properties can be set by translating the property name from dot-delimited to SCREAMING_SNAKE_CASE with a prefix of KAFKA_.

The following variables are pre-declared:

• KAFKA_ZOOKEEPER_CONNECT = zk:2181
• KAFKA_BROKER_ID = 0
• KAFKA_LOG_DIRS = /var/lib/kafka/data
• KAFKA_ADVERTISED_LISTENERS = PLAINTEXT://localhost:9092,BROKER://${HOSTNAME}:9093
• KAFKA_LISTENERS = PLAINTEXT://0.0.0.0:9092,BROKER://0.0.0.0:9093
• KAFKA_LISTENER_SECURITY_PROTOCOL_MAP = BROKER:PLAINTEXT,PLAINTEXT:PLAINTEXT
• KAFKA_INTER_BROKER_LISTENER_NAME = BROKER
• KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR = 1
• KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR = 1
• BROKER_HEAP_OPTS = -Xmx1G

NOTE: variables referenced in the Apache wrapper scripts are not converted into broker properties.

Ports

• 9092

Volumes

• /var/lib/kafka/data

Healthcheck

The image comes with a health check script, /init/healthcheck, that is pre-configured for non-Kubernetes environments.

Example composition

version: "3"

services:
  zk:
    image: itzg/zookeeper
    volumes:
      - zk:/var/lib/zookeeper/data
  kafka-0:
    depends_on:
      - zk
    image: itzg/kafka
    environment:
      KAFKA_BROKER_ID: "0"
      KAFKA_ADVERTISED_LISTENERS: "PLAINTEXT://localhost:9092,BROKER://kafka-0:9093"
    ports:
      - "9092:9092"
    volumes:
      - kafka-0:/var/lib/kafka/data

volumes:
  zk: {}
  kafka-0: {}

Example usage with testcontainers

@Testcontainers
public class TestSomethingWithKafka {

    private static final Network network = Network.newNetwork();

    @Container
    private static final GenericContainer zkContainer = new GenericContainer("itzg/zookeeper")
        .withNetwork(network)
        .withNetworkAliases("zk");

    @Container
    private static final KafkaContainer kafkaContainer = new KafkaContainer(
        DockerImageName.parse("itzg/kafka:3.1.0")
            .asCompatibleSubstituteFor("confluentinc/cp-kafka")
    )
        .dependsOn(zkContainer)
        .withNetwork(network)
        .withExternalZookeeper("zk:2181");

    // ...setup kafka client with "bootstrap.servers" set to kafkaContainer.getBootstrapServers()
}