Apache Kafka 集群未连接到 Docker 上的 Zookeeper

Question

我正在 Docker 上创建一个 3 节点 Zookeeper 和 3 节点 Kafka 集群。我需要将 Kafka 集群链接到 Zookeeper 集群。

下面是 docker-compose.yml 代码 -

version: '2'
services:
  zookeeper-1:
    image: zookeeper:latest
    environment:
      ZOOKEEPER_SERVER_ID: 1
      ZOOKEEPER_CLIENT_PORT: 22181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_INIT_LIMIT: 5
      ZOOKEEPER_SYNC_LIMIT: 2
      ZOOKEEPER_SERVERS: localhost:22888:23888;localhost:32888:33888;localhost:42888:43888

  zookeeper-2:
    image: zookeeper:latest
    environment:
      ZOOKEEPER_SERVER_ID: 2
      ZOOKEEPER_CLIENT_PORT: 32181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_INIT_LIMIT: 5
      ZOOKEEPER_SYNC_LIMIT: 2
      ZOOKEEPER_SERVERS: localhost:22888:23888;localhost:32888:33888;localhost:42888:43888  

  zookeeper-3:
    image: zookeeper:latest
    environment:
      ZOOKEEPER_SERVER_ID: 3
      ZOOKEEPER_CLIENT_PORT: 42181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_INIT_LIMIT: 5
      ZOOKEEPER_SYNC_LIMIT: 2
      ZOOKEEPER_SERVERS: localhost:22888:23888;localhost:32888:33888;localhost:42888:43888    

  kafka1:
    image: abc/kafka:latest
    hostname: kafka1
    network_mode: host
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: localhost:22181,localhost:32181,localhost:42181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:19092
    depends_on:
      - zookeeper-1
      - zookeeper-2
      - zookeeper-3

  kafka2:
    image: abc/kafka:latest
    hostname: kafka2
    network_mode: host
    environment:
      KAFKA_BROKER_ID: 2
      KAFKA_ZOOKEEPER_CONNECT: localhost:22181,localhost:32181,localhost:42181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:29092
    depends_on:
      - zookeeper-1
      - zookeeper-2
      - zookeeper-3

  kafka3:
    image: abc/kafka:latest
    hostname: kafka3
    network_mode: host
    environment:
      KAFKA_BROKER_ID: 3
      KAFKA_ZOOKEEPER_CONNECT: localhost:22181,localhost:32181,localhost:42181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:39092
    depends_on:
      - zookeeper-1
      - zookeeper-2
      - zookeeper-3

当我运行 docker-compose up 命令时，3 节点 zookeeper 集群创建成功。但是没有创建 Kafka 集群。它只在命令行上显示以下错误-

kafka_kafka2_1 exited with code 0
kafka_kafka1_1 exited with code 0
kafka_kafka3_1 exited with code 0

我还在下面添加了用于创建图像的 Dockerfile -

FROM centos:7
MAINTAINER abc@xyz.com

ENV KAFKA_BIN=http://www-eu.apache.org/dist/kafka/0.11.0.2/kafka_2.11-0.11.0.2.tgz

RUN yum install -y wget java-1.8.0-openjdk \
    && cd /tmp && wget -q $KAFKA_BIN \
    && export K_TAR=/tmp/$(ls kafka* | head -1) \
    && mkdir -p /opt/apache/kafka/ && tar -zxf $K_TAR -C /opt/apache/kafka/ \
    && cd /opt/apache/kafka && ln -s $(ls) current \
    && rm -rf $K_TAR

ENV KAFKA_HOME /opt/apache/kafka/current
ENV PATH $PATH:$KAFKA_HOME/bin

ADD resources /home/kafka

RUN groupadd -r kafka \
    && useradd -r -g kafka kafka \
    && mkdir -p /home/kafka \
    && chown -R kafka:kafka /home/kafka \
    && chmod -R +x /home/kafka/scripts \
    && mkdir -p /var/log/kafka \
    && chown -R kafka:kafka /var/log/kafka \
    && mkdir -p /etc/kafka \
    && chown -R kafka:kafka /etc/kafka

USER kafka

没有任何类型的错误消息。有人可以帮我调试这个问题，了解为什么 kafka 集群没有启动。我无法对此进行调试，尤其是因为它仅以代码 0 退出并且没有提供错误消息。

Answer 1

首先，您忘记公开 zookeeper 端口。其次，localhost 意味着 localhost——即使对于 docker 容器也是如此。因此，您的 Kafka 容器会尝试连接到同一容器中的 zookeeper，但这是行不通的。

在这里看看它是如何正确完成的：https://github.com/confluentinc/cp-docker-images/blob/4.0.x/examples/cp-all-in-one/docker-compose.yml

如果您不喜欢这种方法，您可以在不暴露任何端口的情况下进行操作。为此，请在 compose 文件的 zookeeper 环境部分设置 zookeeper 客户端端口：

...
services:
  zookeeper:
    ...
    environment:
       ZOOKEEPER_CLIENT_PORT: 2181

其次，将你的 kafka 容器连接到它：

...
kafka:
  ...
  environment:
    ZOOKEEPER_SERVERS: zookeeper:2181

使用这种方法，一切都将在 docker compose 网络中发生。

Answer 2

Docker 内部的localhost 指的是容器实例，而不是主机。这是 Kafka 安装混乱的主要原因。您需要配置 Kafka 的侦听器以通告不同的主机：端口组合 — 可从容器内访问的组合。

下面显示了如何为多个代理完成此操作的示例。信用：该示例取自 Effective Kafka 随附的回购。

version: "3.2"
services:
  zookeeper:
    image: bitnami/zookeeper:3
    ports:
      - 2181:2181
    environment:
      ALLOW_ANONYMOUS_LOGIN: "yes"
  kafka-0:
    image: bitnami/kafka:2
    ports:
      - 9092:9092
    environment:
      KAFKA_CFG_ZOOKEEPER_CONNECT: zookeeper:2181
      ALLOW_PLAINTEXT_LISTENER: "yes"
      KAFKA_LISTENERS: >-
          INTERNAL://:29092,EXTERNAL://:9092
      KAFKA_ADVERTISED_LISTENERS: >-
          INTERNAL://kafka-0:29092,EXTERNAL://localhost:9092
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: >-
          INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
      KAFKA_INTER_BROKER_LISTENER_NAME: "INTERNAL"
    depends_on:
      - zookeeper
  kafka-1:
    image: bitnami/kafka:2
    ports:
      - 9093:9093
    environment:
      KAFKA_CFG_ZOOKEEPER_CONNECT: zookeeper:2181
      ALLOW_PLAINTEXT_LISTENER: "yes"
      KAFKA_LISTENERS: >-
          INTERNAL://:29092,EXTERNAL://:9093
      KAFKA_ADVERTISED_LISTENERS: >-
          INTERNAL://kafka-1:29092,EXTERNAL://localhost:9093
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: >-
          INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
      KAFKA_INTER_BROKER_LISTENER_NAME: "INTERNAL"
    depends_on:
      - zookeeper
  kafka-2:
    image: bitnami/kafka:2
    ports:
      - 9094:9094
    environment:
      KAFKA_CFG_ZOOKEEPER_CONNECT: zookeeper:2181
      ALLOW_PLAINTEXT_LISTENER: "yes"
      KAFKA_LISTENERS: >-
          INTERNAL://:29092,EXTERNAL://:9094
      KAFKA_ADVERTISED_LISTENERS: >-
          INTERNAL://kafka-2:29092,EXTERNAL://localhost:9094
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: >-
          INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
      KAFKA_INTER_BROKER_LISTENER_NAME: "INTERNAL"
    depends_on:
      - zookeeper
  kafdrop:
    image: obsidiandynamics/kafdrop:latest
    ports:
      - 9000:9000
    environment:
      KAFKA_BROKERCONNECT: >-
          kafka-0:29092,kafka-1:29092,kafka-2:29092
    depends_on:
      - kafka-0
      - kafka-1
      - kafka-2

在这里，连接到代理的应用程序是 Kafdrop，但您可以将其替换为您自己的图像。此外，为简洁起见，该示例仅使用了一个带有 3 个代理的 ZK 节点；这应该是一个简单的改变。

Answer 3

您需要在/etc/hosts 中设置正确的主机名，以便能够连接 docker 外部的 kafka 容器：

 cat /etc/hosts
# This file was automatically generated by WSL. To stop automatic generation of this file, add the following entry to /etc/wsl.conf:
# [network]
# generateHosts = false
127.0.0.1       localhost
127.0.0.1       kafka1
127.0.0.1       kafka2
127.0.0.1       kafka3

这是我的工作配置：

version: '2'
services:
  zookeeper1:
    image: confluentinc/cp-zookeeper:$CP_VERSION
    container_name: zookeeper1
    hostname: zookeeper1
    environment:
      ZOOKEEPER_CLIENT_PORT: 2181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_SERVER_ID: 1
      ZOOKEEPER_SERVERS: "zookeeper1:22888:23888;zookeeper2:22888:23888;zookeeper3:22888:23888"
    ports:
      - 2181:2181
    volumes: 
      - ./data/zoo-1/data:/var/lib/zookeeper/data
      - ./data/zoo-1/log:/var/lib/zookeeper/log

  zookeeper2:
    image: confluentinc/cp-zookeeper:$CP_VERSION
    container_name: zookeeper2
    hostname: zookeeper2
    environment:
      ZOOKEEPER_CLIENT_PORT: 2181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_SERVER_ID: 2
      ZOOKEEPER_SERVERS: "zookeeper1:22888:23888;zookeeper2:22888:23888;zookeeper3:22888:23888"
    ports:
      - 2182:2181
    volumes: 
      - ./data/zoo-2/data:/var/lib/zookeeper/data
      - ./data/zoo-2/log:/var/lib/zookeeper/log

  zookeeper3:
    image: confluentinc/cp-zookeeper:$CP_VERSION
    container_name: zookeeper3
    hostname: zookeeper3
    environment:
      ZOOKEEPER_CLIENT_PORT: 2181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_SERVER_ID: 3
      ZOOKEEPER_SERVERS: "zookeeper1:22888:23888;zookeeper2:22888:23888;zookeeper3:22888:23888"
    ports:
      - 2183:2181
    volumes: 
      - ./data/zoo-3/data:/var/lib/zookeeper/data
      - ./data/zoo-3/log:/var/lib/zookeeper/log

  kafka1:
    image: confluentinc/cp-kafka:$CP_VERSION
    container_name: kafka1
    hostname: kafka1
    depends_on:
      - zookeeper1
      - zookeeper2
      - zookeeper3
    ports:
      - 9091:9091
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: zookeeper1:2181,zookeeper2:2181,zookeeper3:2181
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: INTERNAL:PLAINTEXT,OUTSIDE:PLAINTEXT
      KAFKA_LISTENERS: INTERNAL://:29092,OUTSIDE://:9091
      KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka1:29092,OUTSIDE://kafka1:9091
      KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_LOG_DIRS: /var/lib/kafka/logs


  kafka2:
    image: confluentinc/cp-kafka:$CP_VERSION
    container_name: kafka2
    hostname: kafka2
    depends_on:
      - zookeeper1
      - zookeeper2
      - zookeeper3
    ports:
      - 9092:9092
    environment:
      KAFKA_BROKER_ID: 2
      KAFKA_ZOOKEEPER_CONNECT: zookeeper1:2181,zookeeper2:2181,zookeeper3:2181
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: INTERNAL:PLAINTEXT,OUTSIDE:PLAINTEXT
      KAFKA_LISTENERS: INTERNAL://:29092,OUTSIDE://:9092
      KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka2:29092,OUTSIDE://kafka2:9092
      KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_LOG_DIRS: /var/lib/kafka/logs

  kafka3:
    image: confluentinc/cp-kafka:$CP_VERSION
    container_name: kafka3
    hostname: kafka3
    depends_on:
      - zookeeper1
      - zookeeper2
      - zookeeper3
    ports:
      - 9093:9093
    environment:
      KAFKA_BROKER_ID: 3
      KAFKA_ZOOKEEPER_CONNECT: zookeeper1:2181,zookeeper2:2181,zookeeper3:2181
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: INTERNAL:PLAINTEXT,OUTSIDE:PLAINTEXT
      KAFKA_LISTENERS: INTERNAL://:29092,OUTSIDE://:9093
      KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka3:29092,OUTSIDE://kafka3:9093
      KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_LOG_DIRS: /var/lib/kafka/logs