services:
    kafka-1:
        image: apache/kafka:latest
        container_name: kafka-1
        hostname: kafka-1
        ports:
            - "9092:9092" # External Client Port
        environment:
            KAFKA_NODE_ID: 1
            KAFKA_PROCESS_ROLES: broker,controller

            # --- NETWORKING CONFIGS ---
            # 1. Listeners: Where the process listens inside the container
            # CONTROLLER:9093, INTERNAL:29092, EXTERNAL:9092
            KAFKA_LISTENERS: CONTROLLER://:9093,INTERNAL://:29092,EXTERNAL://:9092

            # 2. Advertised Listeners: What the broker tells others to connect to
            # Internal -> within docker network, this network is made by docker-compose
            # see `sudo docker network ls`
            # External -> for my python script

            # these are the two ways you can talk to me
            KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka-1:29092,EXTERNAL://localhost:9092

            # 3. Security Map: Define the protocol for the new names
            KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT

            # 4. Inter-broker communication MUST use the INTERNAL listener
            KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL # when brokers talk to each other, use INTERNAL
            KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER # controller uses CONTROLLER listener

            # Quorum voters use the Internal Docker DNS
            KAFKA_CONTROLLER_QUORUM_VOTERS: 1@kafka-1:9093,2@kafka-2:9093,3@kafka-3:9093

            KAFKA_LOG_DIRS: /var/lib/kafka/data

            # --- REPLICATION DEFAULTS ---
            KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 3
            KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 3
            KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 2
            KAFKA_NUM_PARTITIONS: 3
            KAFKA_DEFAULT_REPLICATION_FACTOR: 3
            KAFKA_MIN_INSYNC_REPLICAS: 2
        volumes:
            - ./kafka-1-data:/var/lib/kafka/data

    kafka-2:
        image: apache/kafka:latest
        container_name: kafka-2
        hostname: kafka-2
        ports:
            - "9094:9092" # Host:9094 -> Container:9092
        environment:
            KAFKA_NODE_ID: 2
            KAFKA_PROCESS_ROLES: broker,controller

            # Listeners
            KAFKA_LISTENERS: CONTROLLER://:9093,INTERNAL://:29092,EXTERNAL://:9092
            # Advertised: Internal uses kafka-2, External uses localhost:9094
            KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka-2:29092,EXTERNAL://localhost:9094

            KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
            KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
            KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER
            KAFKA_CONTROLLER_QUORUM_VOTERS: 1@kafka-1:9093,2@kafka-2:9093,3@kafka-3:9093

            KAFKA_LOG_DIRS: /var/lib/kafka/data
            # --- SAME DEFAULTS ---
            KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 3
            KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 3
            KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 2
            KAFKA_NUM_PARTITIONS: 3
            KAFKA_DEFAULT_REPLICATION_FACTOR: 3
            KAFKA_MIN_INSYNC_REPLICAS: 2
        volumes:
            - ./kafka-2-data:/var/lib/kafka/data

    kafka-3:
        image: apache/kafka:latest
        container_name: kafka-3
        hostname: kafka-3
        ports:
            - "9096:9092" # Host:9096 -> Container:9092
        environment:
            KAFKA_NODE_ID: 3
            KAFKA_PROCESS_ROLES: broker,controller

            # Listeners
            KAFKA_LISTENERS: CONTROLLER://:9093,INTERNAL://:29092,EXTERNAL://:9092
            # Advertised: Internal uses kafka-3, External uses localhost:9096
            KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka-3:29092,EXTERNAL://localhost:9096

            KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
            KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
            KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER
            KAFKA_CONTROLLER_QUORUM_VOTERS: 1@kafka-1:9093,2@kafka-2:9093,3@kafka-3:9093

            KAFKA_LOG_DIRS: /var/lib/kafka/data
            # --- SAME DEFAULTS ---
            KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 3
            KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 3
            KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 2
            KAFKA_NUM_PARTITIONS: 3
            KAFKA_DEFAULT_REPLICATION_FACTOR: 3
            KAFKA_MIN_INSYNC_REPLICAS: 2
        volumes:
            - ./kafka-3-data:/var/lib/kafka/data