feat: Implemented `HaproxyShardingPublisherStrategy`

* Implemented a first simple `ShardingPublisherStrategy`, that uses the
 https://www.haproxy.com/documentation/haproxy-runtime-api/[HAProxy Runntime API]
 to publish changed ownerships.
* Added configuration-properties `kafka.haproxyRuntimeApi` and
  `kafka.haproxyMap` to configure the strategy.

diff --git a/src/main/java/de/juplo/kafka/chat/backend/ChatBackendProperties.java b/src/main/java/de/juplo/kafka/chat/backend/ChatBackendProperties.java
index c0b4934..9a73f6f 100644 (file)
--- a/src/main/java/de/juplo/kafka/chat/backend/ChatBackendProperties.java
+++ b/src/main/java/de/juplo/kafka/chat/backend/ChatBackendProperties.java
@@ -43,6 +43,8 @@ public class ChatBackendProperties
     private String infoChannelTopic = "info_channel";
     private String dataChannelTopic = "data_channel";
     private int numPartitions = 2;
+    private String haproxyRuntimeApi = "haproxy:8401";
+    private String haproxyMap = "/usr/local/etc/haproxy/sharding.map";
   }
 
   public enum ServiceType { inmemory, kafka }

diff --git a/src/main/java/de/juplo/kafka/chat/backend/implementation/haproxy/HaproxyShardingPublisherStrategy.java b/src/main/java/de/juplo/kafka/chat/backend/implementation/haproxy/HaproxyShardingPublisherStrategy.java
new file mode 100644 (file)
index 0000000..3caaeb3
--- /dev/null
+++ b/src/main/java/de/juplo/kafka/chat/backend/implementation/haproxy/HaproxyShardingPublisherStrategy.java
@@ -0,0 +1,41 @@
+package de.juplo.kafka.chat.backend.implementation.haproxy;
+
+import de.juplo.kafka.chat.backend.domain.ShardingPublisherStrategy;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import reactor.core.publisher.Mono;
+
+import java.io.IOException;
+import java.net.SocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.SocketChannel;
+
+
+@RequiredArgsConstructor
+@Slf4j
+public class HaproxyShardingPublisherStrategy implements ShardingPublisherStrategy
+{
+  private final SocketAddress haproxyAddress;
+  private final String map;
+  private final String instanceId;
+
+
+  @Override
+  public Mono<String> publishOwnership(int shard)
+  {
+    try
+    {
+      SocketChannel socketChannel = SocketChannel.open(haproxyAddress);
+      String command = "set map " + map + " " + Integer.toString(shard) + " " + instanceId + "\n";
+      byte[] commandBytes = command.getBytes();
+      ByteBuffer buffer = ByteBuffer.wrap(commandBytes);
+      socketChannel.write(buffer);
+      socketChannel.close();
+      return Mono.just(instanceId);
+    }
+    catch (IOException e)
+    {
+      return Mono.error(e);
+    }
+  }
+}

diff --git a/src/main/java/de/juplo/kafka/chat/backend/implementation/kafka/KafkaServicesConfiguration.java b/src/main/java/de/juplo/kafka/chat/backend/implementation/kafka/KafkaServicesConfiguration.java
index c3027fa..f8bebd6 100644 (file)
--- a/src/main/java/de/juplo/kafka/chat/backend/implementation/kafka/KafkaServicesConfiguration.java
+++ b/src/main/java/de/juplo/kafka/chat/backend/implementation/kafka/KafkaServicesConfiguration.java
@@ -3,6 +3,7 @@ package de.juplo.kafka.chat.backend.implementation.kafka;
 import de.juplo.kafka.chat.backend.ChatBackendProperties;
 import de.juplo.kafka.chat.backend.domain.ChatHomeService;
 import de.juplo.kafka.chat.backend.domain.ShardingPublisherStrategy;
+import de.juplo.kafka.chat.backend.implementation.haproxy.HaproxyShardingPublisherStrategy;
 import de.juplo.kafka.chat.backend.implementation.kafka.messages.AbstractMessageTo;
 import de.juplo.kafka.chat.backend.implementation.kafka.messages.data.EventChatMessageReceivedTo;
 import de.juplo.kafka.chat.backend.implementation.kafka.messages.info.EventChatRoomCreated;
@@ -21,8 +22,8 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.kafka.support.serializer.JsonDeserializer;
 import org.springframework.kafka.support.serializer.JsonSerializer;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
-import reactor.core.publisher.Mono;
 
+import java.net.InetSocketAddress;
 import java.time.Clock;
 import java.time.ZoneId;
 import java.util.HashMap;
@@ -285,15 +286,15 @@ public class KafkaServicesConfiguration
   }
 
   @Bean
-  ShardingPublisherStrategy shardingPublisherStrategy()
+  ShardingPublisherStrategy shardingPublisherStrategy(
+      ChatBackendProperties properties)
   {
-    return new ShardingPublisherStrategy() {
-      @Override
-      public Mono<String> publishOwnership(int shard)
-      {
-        return Mono.just(Integer.toString(shard));
-      }
-    };
+    String[] parts = properties.getKafka().getHaproxyRuntimeApi().split(":");
+    InetSocketAddress haproxyAddress = new InetSocketAddress(parts[0], Integer.valueOf(parts[1]));
+    return new HaproxyShardingPublisherStrategy(
+        haproxyAddress,
+        properties.getKafka().getHaproxyMap(),
+        properties.getInstanceId());
   }
 
   @Bean