Flink Source Kafka

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Kafka Setup

wget https://downloads.apache.org/kafka/2.8.0/kafka_2.12-2.8.0.tgz

tar zxvf kafka_2.12-2.8.0.tgz -C ~/app

cd ~/app/kafka_2.12-2.8.0

# start the zookeeper service
bin/zookeeper-server-start.sh config/zookeeper.properties

# start the Kafka broker service
bin/kafka-server-start.sh config/server.properties

# create topic
bin/kafka-topics.sh --create --topic flink_topic --bootstrap-server localhost:9092

# describle message
bin/kafka-topics.sh --describe --topic flink_topic --bootstrap-server localhost:9092

# produce message
bin/kafka-console-producer.sh --topic flink_topic --bootstrap-server localhost:9092

# consumer message
bin/kafka-console-consumer.sh --topic flink_topic --from-beginning --bootstrap-server localhost:9092

Maven Dependency

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.fool</groupId>
    <artifactId>flink</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-java</artifactId>
            <version>1.12.5</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_2.12</artifactId>
            <version>1.12.5</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_2.12</artifactId>
            <version>1.12.5</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-connector-kafka_2.12</artifactId>
            <version>1.12.5</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
        </dependency>

    </dependencies>

</project>

SRC

SourceKafkaTest.java

package org.fool.flink.source;

import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;

import java.util.Properties;

public class SourceKafkaTest {
    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment environment = StreamExecutionEnvironment.getExecutionEnvironment();

        Properties properties = new Properties();
        properties.setProperty("bootstrap.servers", "localhost:9092");
        properties.setProperty("group.id", "consumer-group");
        properties.setProperty("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        properties.setProperty("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        properties.setProperty("auto.offset.reset", "latest");

        DataStream<String> dataStreamSource = environment.addSource(new FlinkKafkaConsumer<>("flink_topic", new SimpleStringSchema(), properties));

        dataStreamSource.print();

        environment.execute("source kafka job");
    }
}

Run

Kafka Producer

Console Output

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