docker-compose.yml

version: '3.8' #Docker compose version 

services: #Containers to run
  zookeeper: # First container (Service)
    image: confluentinc/cp-zookeeper:latest  #zookeeper docker image
    container_name: zookeeper #container name
    environment: #Envirnoment variables
      ZOOKEEPER_CLIENT_PORT: 2181
      ZOOKEEPER_TICK_TIME: 2000
    ports: #maps port 2181 from the host to por 2181 inside the zookeeper container, allows to access zookeeper on port 2181 of your host machine
      - 2181:2181

  kafka-test: # Second container (Service)
    image: confluentinc/cp-kafka:latest #latest version of kafka docker image
    container_name: kafka-test #Name of the container
    depends_on:
      - zookeeper #depends on zookeeper so kafka will not start until zookeeper service is up and running
    environment:
      KAFKA_BROKER_ID: 1 #The unique identifier for this Kafka broker (set to 1 in this case).
      KAFKA_ZOOKEEPER_CONNECT: 'zookeeper:2181' #The connection information for ZooKeeper, which is accessible at zookeeper:2181.
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_INTERNAL:PLAINTEXT #Defines the security protocols for Kafka listeners.
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:9092,PLAINTEXT_INTERNAL://broker:29092 #Defines the advertised endpoints for clients to connect to the Kafka broker.
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1
      KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1
    ports:
      - "9092:9092" # port to use to connect from kafka broker to local host port
    expose:
     - "9093"