AWS Advanced JDBC Wrapperを使ってAmazon Auroraのライター/リーダーの接続を動的に切り替える

dependencies {
    implementation("software.amazon.jdbc:aws-advanced-jdbc-wrapper:2.6.6")
    runtimeOnly("com.mysql:mysql-connector-j:8.2.0")
    implementation("org.springframework.boot:spring-boot-starter-data-jpa")
}

spring:
  datasource:
    aws-jdbc-wrapper:
      url: ${JDBC_CONNECTION_STRING}
      username: ${DB_USERNAME}
      password: ${DB_PASSWORD}
      wrapper-plugins: initialConnection,auroraConnectionTracker,readWriteSplitting,failover2,efm2
      wrapper-dialect: aurora-mysql
      reader-host-selector-strategy: random

package com.example.demo.config

import org.springframework.boot.context.properties.ConfigurationProperties
import org.springframework.context.annotation.Profile

@ConfigurationProperties(prefix = "spring.datasource.aws-jdbc-wrapper")
data class AwsJdbcWrapperConfig(
    val url: String,
    val username: String,
    val password: String,
    val wrapperPlugins: String,
    val wrapperDialect: String,
    val readerHostSelectorStrategy: String,
    val clusterInstanceHostPattern: String,
)

package com.example.demo.config

import com.zaxxer.hikari.HikariConfig
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.context.annotation.Profile
import org.springframework.jdbc.datasource.SimpleDriverDataSource
import software.amazon.jdbc.Driver
import software.amazon.jdbc.HikariPooledConnectionProvider
import software.amazon.jdbc.ds.AwsWrapperDataSource
import software.amazon.jdbc.hostlistprovider.RdsHostListProvider
import java.util.Properties
import java.util.concurrent.TimeUnit
import javax.sql.DataSource

@Configuration
class DataSourceConfig(
    private val awsJdbcWrapperConfig: AwsJdbcWrapperConfig,
) {
    @Bean
    fun dataSource(): DataSource {
        // SimpleDriverDataSourceを利用することでSpring BootデフォルトのHikariCPを無効化する
        // AWS JDBC Wrapper内部のコネクションプールを使用するため
        val ds = SimpleDriverDataSource()
        val properties = Properties()

        // JDBC Wrapperの設定
        properties["wrapperPlugins"] = awsJdbcWrapperConfig.wrapperPlugins
        properties["wrapperDialect"] = awsJdbcWrapperConfig.wrapperDialect
        properties["readerHostSelectorStrategy"] = awsJdbcWrapperConfig.readerHostSelectorStrategy
        properties["connectTimeout"] = TimeUnit.SECONDS.toMillis(30).toString()

        ds.setDriverClass(Driver::class.java)
        ds.url = awsJdbcWrapperConfig.url
        ds.username = awsJdbcWrapperConfig.username
        ds.password = awsJdbcWrapperConfig.password
        ds.connectionProperties = properties

        // JDBC Wrapper内部のコネクションプール（HikariCP）を有効にする
        Driver.setCustomConnectionProvider(
            HikariPooledConnectionProvider { _, _ ->
                HikariConfig().apply {
                    maximumPoolSize = 10
                    minimumIdle = 2
                    connectionTimeout = TimeUnit.SECONDS.toMillis(30)
                    idleTimeout = TimeUnit.MINUTES.toMillis(10)
                    maxLifetime = TimeUnit.MINUTES.toMillis(30)
                }
            },
        )

        return ds
    }
}

package com.example.demo.service

import com.example.demo.repository.UserRepository
import org.springframework.stereotype.Service
import org.springframework.transaction.annotation.Transactional

@Service
@Transactional(readOnly = true) // デフォルトはreadonly
class UserService(
    private val userRepository: UserRepository,
) {
    // リーダーに振り分けられる
    fun findAll(): List<User> {
        return userRepository.findAll()
    }
    // ライターに振り分けられる
    @Transactional
    fun create(name: String, email: String): User {
        val user = User(name = name, email = email)
        return userRepository.save(user)
    }
}

logging:
  level:
    software.amazon.jdbc: TRACE

Reader connection set to 'xxx.xxxx.rds.amazonaws.com:3306/
Switched from a writer to a reader host. New reader host: 'xxx.xxxx.ap-northeast-1.rds.amazonaws.com:3306/
Successfully connected to a new reader host: 'xxx.xxxx.ap-northeast-1.rds.amazonaws.com:3306