如何使用 docker 快速启动一个 kafka 应用？

介绍

在阿里云服务器启动测试用的 Kafka 应用。由于资源有限，使用单机模式。

1.下载镜像

• zookeeper

docker pull zookeeper

• kafka

docker pull wurstmeister/kafka

2.启动 zookeeper

• 单机方式

docker run -d --name docker_zookeeper -p 2181:2181 -t zookeeper

3.启动 Kafka

docker run -d --name docker_kafka \
-p 9092:9092 \
--add-host=${hostname}:${服务器IP}\
-e KAFKA_BROKER_ID=0 \
-e KAFKA_ZOOKEEPER_CONNECT=${hostname}:2181 \
-e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://${hostname}:9092 \
-e KAFKA_JVM_PERFORMANCE_OPTS="-Xmx256m -Xms256m" \
-e KAFKA_LISTENERS=PLAINTEXT://0.0.0.0:9092 wurstmeister/kafka

说明：
由于阿里云服务器内外网ip不一致，因此为了外网能够正常访问 Kafka，让内外网使用一致的 hostname 访问：

• --add-host：添加容器 hosts 映射
  • hostname 是云服务器的 hostname；
  • 服务器 ip 为 阿里云内网。

之后，需要在外网机器的 hosts 中添加：

# 阿里云服务器地址映射
${服务器外网IP} ${服务器hostname}

此外，Kafka 的内存默认占用 1G，云服务器资源有限，因此指定 Kafka 的 jvm 参数

• -e KAFKA_JVM_PERFORMANCE_OPTS

4.命令行验证

• 进入容器

# 进入容器
docker exec -it ${CONTAINER ID} /bin/bash
cd opt/kafka

• 创建一个topic

bin/kafka-topics.sh --create --zookeeper ${hostname}:2181 --replication-factor 1 --partitions 1 --topic mykafka

• 运行一个生产者并发送消息

bin/kafka-console-producer.sh --bootstrap-server ${hostname}:9092 --topic mykafka

例如：

bash-5.1# bin/kafka-console-producer.sh --bootstrap-server zhy:9092 --topic mykafka
>zhy

• 运行一个消费者并接受消息

bin/kafka-console-consumer.sh --bootstrap-server ${hostname}:9092 --topic mykafka --from-beginning

例如：

bash-5.1# bin/kafka-console-consumer.sh --bootstrap-server zhy:9092 --topic mykafka --from-beginning
zhy

5.外网Java API 验证

• 启动一个消费者：

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.serialization.StringDeserializer;

import java.time.Duration;
import java.util.ArrayList;
import java.util.Properties;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class CustomConsumer {

    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "zhy:9092"); // 此处也可以使用 ip
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        properties.put(ConsumerConfig.GROUP_ID_CONFIG, "test");

        KafkaConsumer<String, String> kafkaConsumer = new KafkaConsumer<>(properties);

        // 订阅主题 mykafka
        kafkaConsumer.subscribe(Stream.of("mykafka").collect(Collectors.toList()));

        // 3 消费数据
        while (true) {
            ConsumerRecords<String, String> consumerRecords = kafkaConsumer.poll(Duration.ofSeconds(1));
            for (ConsumerRecord<String, String> consumerRecord : consumerRecords) {
                System.out.println(consumerRecord);
            }
            kafkaConsumer.commitAsync();
        }
    }
}

• 生产者(如果没有上面为 Kafka 容器做hostname映射，并且使用hostname，此时外网始终无法发送数据)

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.Properties;

public class CustomProducer {

    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "zhy:9092");
        properties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        properties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        KafkaProducer<String, String> producer = new KafkaProducer<>(properties);
        
        for (int i = 0; i < 5; i++) {
            producer.send(new ProducerRecord<>("mykafka", "CustomProducerTest@" + i));
        }
        producer.close();
    }
}

此时，之前使用 JavaAPI 启动的 消费者输出如下：

ConsumerRecord(topic = mykafka, partition = 0, leaderEpoch = 0, offset = 1, CreateTime = 1649684611004, serialized key size = -1, serialized value size = 20, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = CustomProducerTest@0)
ConsumerRecord(topic = mykafka, partition = 0, leaderEpoch = 0, offset = 2, CreateTime = 1649684611036, serialized key size = -1, serialized value size = 20, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = CustomProducerTest@1)
ConsumerRecord(topic = mykafka, partition = 0, leaderEpoch = 0, offset = 3, CreateTime = 1649684611036, serialized key size = -1, serialized value size = 20, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = CustomProducerTest@2)
ConsumerRecord(topic = mykafka, partition = 0, leaderEpoch = 0, offset = 4, CreateTime = 1649684611036, serialized key size = -1, serialized value size = 20, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = CustomProducerTest@3)
ConsumerRecord(topic = mykafka, partition = 0, leaderEpoch = 0, offset = 5, CreateTime = 1649684611036, serialized key size = -1, serialized value size = 20, headers = RecordHeaders(headers = [], isReadOnly = false), key = null, value = CustomProducerTest@4)

同时，可以在之前打开的消费者窗口看见内容：

bash-5.1# bin/kafka-console-consumer.sh --bootstrap-server zhy:9092 --topic mykafka --from-beginning
zhy
CustomProducerTest@0
CustomProducerTest@1
CustomProducerTest@2
CustomProducerTest@3
CustomProducerTest@4