From 4bb2f181202664ede1f3b1769904b46b73f26679 Mon Sep 17 00:00:00 2001
From: Kai Moritz <kai@juplo.de>
Date: Tue, 29 Oct 2024 14:05:40 +0100
Subject: [PATCH] Setup, um  `grundlagen/simple-consumer` als Consumer Group zu
 skalieren

---
 .dockerignore                                 |   3 -
 .maven-dockerexclude                          |   1 -
 .maven-dockerinclude                          |   2 -
 Dockerfile                                    |   6 -
 docker/docker-compose.yml                     |  12 +-
 pom.xml                                       |  98 -------------
 .../java/de/juplo/kafka/ExampleConsumer.java  | 132 ------------------
 src/main/resources/logback.xml                |  16 ---
 8 files changed, 10 insertions(+), 260 deletions(-)
 delete mode 100644 .dockerignore
 delete mode 100644 .maven-dockerexclude
 delete mode 100644 .maven-dockerinclude
 delete mode 100644 Dockerfile
 delete mode 100644 pom.xml
 delete mode 100644 src/main/java/de/juplo/kafka/ExampleConsumer.java
 delete mode 100644 src/main/resources/logback.xml

diff --git a/.dockerignore b/.dockerignore
deleted file mode 100644
index 49f82a9..0000000
--- a/.dockerignore
+++ /dev/null
@@ -1,3 +0,0 @@
-*
-!target/*.jar
-!target/libs/*.jar
diff --git a/.maven-dockerexclude b/.maven-dockerexclude
deleted file mode 100644
index 72e8ffc..0000000
--- a/.maven-dockerexclude
+++ /dev/null
@@ -1 +0,0 @@
-*
diff --git a/.maven-dockerinclude b/.maven-dockerinclude
deleted file mode 100644
index a00c65f..0000000
--- a/.maven-dockerinclude
+++ /dev/null
@@ -1,2 +0,0 @@
-target/*.jar
-target/libs/*.jar
diff --git a/Dockerfile b/Dockerfile
deleted file mode 100644
index 22819af..0000000
--- a/Dockerfile
+++ /dev/null
@@ -1,6 +0,0 @@
-FROM eclipse-temurin:21-jre
-VOLUME /tmp
-COPY target/*.jar /opt/app.jar
-COPY target/libs /opt/libs
-ENTRYPOINT [ "java", "-jar", "/opt/app.jar" ]
-CMD [ "kafka:9092", "test", "my-group", "DCKR" ]
diff --git a/docker/docker-compose.yml b/docker/docker-compose.yml
index cba608b..3b5752c 100644
--- a/docker/docker-compose.yml
+++ b/docker/docker-compose.yml
@@ -193,9 +193,17 @@ services:
     image: juplo/simple-producer:1.0-SNAPSHOT
     command: kafka:9092 test producer
 
-  consumer:
+  consumer-1:
     image: juplo/simple-consumer:1.0-SNAPSHOT
-    command: kafka:9092 test my-group consumer
+    command: kafka:9092 test my-group consumer-1
+
+  consumer-2:
+    image: juplo/simple-consumer:1.0-SNAPSHOT
+    command: kafka:9092 test my-group consumer-2
+
+  consumer-3:
+    image: juplo/simple-consumer:1.0-SNAPSHOT
+    command: kafka:9092 test my-group consumer-3
 
 volumes:
   zookeeper-data:
diff --git a/pom.xml b/pom.xml
deleted file mode 100644
index 2d81d24..0000000
--- a/pom.xml
+++ /dev/null
@@ -1,98 +0,0 @@
-<?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>
-
-  <parent>
-    <groupId>org.springframework.boot</groupId>
-    <artifactId>spring-boot-starter-parent</artifactId>
-    <version>3.3.4</version>
-    <relativePath/> <!-- lookup parent from repository -->
-  </parent>
-
-  <groupId>de.juplo.kafka</groupId>
-  <artifactId>simple-consumer</artifactId>
-  <name>Simple Consumer-Group</name>
-  <description>Super Simple Consumer-Group, that is implemented as a plain Java-program</description>
-  <version>1.0-SNAPSHOT</version>
-
-  <properties>
-    <java.version>21</java.version>
-  </properties>
-
-  <dependencies>
-    <dependency>
-      <groupId>org.apache.kafka</groupId>
-      <artifactId>kafka-clients</artifactId>
-    </dependency>
-    <dependency>
-      <groupId>org.projectlombok</groupId>
-      <artifactId>lombok</artifactId>
-    </dependency>
-    <dependency>
-      <groupId>ch.qos.logback</groupId>
-      <artifactId>logback-classic</artifactId>
-    </dependency>
-  </dependencies>
-
-  <build>
-    <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-dependency-plugin</artifactId>
-        <executions>
-          <execution>
-            <id>copy-dependencies</id>
-            <phase>package</phase>
-            <goals>
-              <goal>copy-dependencies</goal>
-            </goals>
-            <configuration>
-              <outputDirectory>${project.build.directory}/libs</outputDirectory>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-jar-plugin</artifactId>
-        <configuration>
-          <archive>
-            <manifest>
-              <addClasspath>true</addClasspath>
-              <classpathPrefix>libs/</classpathPrefix>
-              <mainClass>de.juplo.kafka.ExampleConsumer</mainClass>
-            </manifest>
-          </archive>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>pl.project13.maven</groupId>
-        <artifactId>git-commit-id-plugin</artifactId>
-      </plugin>
-      <plugin>
-        <groupId>io.fabric8</groupId>
-        <artifactId>docker-maven-plugin</artifactId>
-        <version>0.45.0</version>
-        <configuration>
-          <images>
-            <image>
-              <name>juplo/%a:%v</name>
-            </image>
-          </images>
-        </configuration>
-        <executions>
-          <execution>
-             <id>build</id>
-             <phase>package</phase>
-             <goals>
-               <goal>build</goal>
-             </goals>
-          </execution>
-        </executions>
-      </plugin>
-    </plugins>
-  </build>
-
-</project>
diff --git a/src/main/java/de/juplo/kafka/ExampleConsumer.java b/src/main/java/de/juplo/kafka/ExampleConsumer.java
deleted file mode 100644
index 3634875..0000000
--- a/src/main/java/de/juplo/kafka/ExampleConsumer.java
+++ /dev/null
@@ -1,132 +0,0 @@
-package de.juplo.kafka;
-
-import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.clients.consumer.ConsumerRecord;
-import org.apache.kafka.clients.consumer.ConsumerRecords;
-import org.apache.kafka.clients.consumer.Consumer;
-import org.apache.kafka.clients.consumer.KafkaConsumer;
-import org.apache.kafka.common.errors.WakeupException;
-import org.apache.kafka.common.serialization.StringDeserializer;
-
-import java.time.Duration;
-import java.util.Arrays;
-import java.util.Properties;
-
-
-@Slf4j
-public class ExampleConsumer
-{
-  private final String id;
-  private final String topic;
-  private final Consumer<String, String> consumer;
-
-  private volatile boolean running = false;
-  private long consumed = 0;
-
-  public ExampleConsumer(
-    String broker,
-    String topic,
-    String groupId,
-    String clientId)
-  {
-    Properties props = new Properties();
-    // Konfiguration für den Consumer zusammenstellen
-
-    this.id = clientId;
-    this.topic = topic;
-    consumer = new KafkaConsumer<>(props);
-  }
-
-
-  public void run()
-  {
-    try
-    {
-      log.info("{} - Subscribing to topic {}", id, topic);
-      // TODO: subscribe!
-      running = true;
-
-      while (true)
-      {
-        // TODO:
-        // Über consumer.poll() Nachrichten abrufen und für die
-        // empfangenen Nachrichten die Methode handleRecord
-        // aufrufen.
-      }
-    }
-    catch(WakeupException e)
-    {
-      log.info("{} - Consumer was signaled to finish its work", id);
-    }
-    catch(Exception e)
-    {
-      log.error("{} - Unexpected error, unsubscribing!", id, e);
-    }
-    finally
-    {
-      running = false;
-      log.info("{} - Closing the KafkaConsumer", id);
-      consumer.close();
-      log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
-    }
-  }
-
-  private void handleRecord(
-    String topic,
-    Integer partition,
-    Long offset,
-    String key,
-    String value)
-  {
-    consumed++;
-    log.info("{} - {}: {}/{} - {}={}", id, offset, topic, partition, key, value);
-  }
-
-
-  public static void main(String[] args) throws Exception
-  {
-    String broker = ":9092";
-    String topic = "test";
-    String groupId = "my-group";
-    String clientId = "DEV";
-
-    switch (args.length)
-    {
-      case 4:
-        clientId = args[3];
-      case 3:
-        groupId = args[2];
-      case 2:
-        topic = args[1];
-      case 1:
-        broker = args[0];
-    }
-
-
-    ExampleConsumer instance = new ExampleConsumer(broker, topic, groupId, clientId);
-
-    Runtime.getRuntime().addShutdownHook(new Thread(() ->
-    {
-      instance.consumer.wakeup();
-
-      while (instance.running)
-      {
-        log.info("Waiting for main-thread...");
-        try
-        {
-          Thread.sleep(1000);
-        }
-        catch (InterruptedException e) {}
-      }
-      log.info("Shutdown completed.");
-    }));
-
-    log.info(
-        "Running ExampleConsumer: broker={}, topic={}, group-id={}, client-id={}",
-        broker,
-        topic,
-        groupId,
-        clientId);
-    instance.run();
-  }
-}
diff --git a/src/main/resources/logback.xml b/src/main/resources/logback.xml
deleted file mode 100644
index 7a25e76..0000000
--- a/src/main/resources/logback.xml
+++ /dev/null
@@ -1,16 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<configuration>
-
-  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
-    <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
-      <Pattern>%d{HH:mm:ss.SSS} | %highlight(%-5level) %msg%n</Pattern>
-    </encoder>
-  </appender>
-
-  <logger name="de.juplo" level="TRACE"/>
-
-  <root level="INFO">
-    <appender-ref ref="STDOUT" />
-  </root>
-
-</configuration>
-- 
2.20.1