feat: 컨슈머 설정 클래스 구현

- 컨슈머 관련 설정 + 메트릭 측정을 위한 MeterBinder 빈
- KafkaConsumer는 Thread-Safe하지 않기에 빈 등록 X

src/main/java/com/sangdol/consumer/infrastructure/kafka/consumer/ConsumerConfiguration.java

@@ -0,0 +1,88 @@
+package com.sangdol.consumer.infrastructure.kafka.consumer;
+
+import java.util.Properties;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
+
+import org.apache.kafka.clients.CommonClientConfigs;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.security.auth.SecurityProtocol;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import com.sangdol.consumer.domain.TestRecord;
+import com.sangdol.consumer.infrastructure.kafka.common.KafkaProperties;
+
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.binder.MeterBinder;
+import lombok.RequiredArgsConstructor;
+
+@Configuration
+@RequiredArgsConstructor
+@EnableConfigurationProperties(value = KafkaProperties.class)
+public class ConsumerConfiguration {
+
+	private final KafkaProperties kafkaProperties;
+
+	public KafkaConsumer<String, TestRecord> kafkaConsumer() {
+		KafkaConsumer<String, TestRecord> consumer = new KafkaConsumer<>(consumerProperties());
+		consumer.subscribe(kafkaProperties.getConsumer().topics(), new RebalanceListener(consumer));
+
+		return consumer;
+	}
+
+	@Bean
+	public MeterBinder elapsedTime(ConsumerStats consumerStats) {
+		String consumerProtocol = kafkaProperties.getConsumer().protocol();
+		return registry -> Gauge.builder("elapsed.time", consumerStats, ConsumerStats::averageTime)
+			.tag("protocol", consumerProtocol)
+			.register(registry);
+	}
+
+	@Bean
+	public ConsumerStats consumerStats() {
+		Integer workerThreads = kafkaProperties.getConsumer().workerThreads();
+		return new ConsumerStats(workerThreads);
+	}
+
+	@Bean
+	public ConsumerPool consumerPool() {
+		ThreadFactory threadFactory = new ThreadFactoryBuilder()
+			.setNameFormat("consumer-pool-%d")
+			.build();
+		int workerThreads = kafkaProperties.getConsumer().workerThreads();
+
+		return new ConsumerPool(
+			Executors.newFixedThreadPool(workerThreads, threadFactory),
+			workerThreads
+		);
+	}
+
+	private Properties consumerProperties() {
+		KafkaProperties.Consumer consumer = kafkaProperties.getConsumer();
+		KafkaProperties.BootStrapServers bootStrapServers = kafkaProperties.getBootStrapServers();
+		Properties properties = new Properties();
+		properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,
+			bootStrapServers.getAddressByProtocol(consumer.protocol()));
+		properties.put(ConsumerConfig.GROUP_ID_CONFIG, consumer.groupId());
+		properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, consumer.keyDeserializer());
+		properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, consumer.valueDeserializer());
+		properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, consumer.autoOffsetReset());
+		properties.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, consumer.enableAutoCommit());
+		properties.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, consumer.maxPollRecords());
+
+		applyRemainPropsBySslEnabled(consumer.isSslEnabled(), properties);
+
+		return properties;
+	}
+
+	private void applyRemainPropsBySslEnabled(boolean isSslEnabled, Properties properties) {
+		if (isSslEnabled) {
+			properties.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, SecurityProtocol.SSL.name);
+			properties.putAll(kafkaProperties.getSsl().toPropsMap());
+		}
+	}
+}