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Tutorial: Getting Started with the AWS Advanced JDBC Driver, Spring Boot and Hibernate for load-balanced write and read-only connections (Two Datasources)

In this tutorial, you will set up a Spring Boot and Hibernate application with the AWS Advanced JDBC Driver, and use two datasources to fetch and update data from an Aurora PostgreSQL database. One datasource is configured to provide a writer connection. The other datasource is configured to provide a reader connection to off load a writer node from read-only queries. Both datasources provide pooled connections through AWS Advanced JDBC Driver internal connection pool configuration.

Note: this tutorial was written using the following technologies:

  • Spring Boot 2.7.1
  • Hibernate
  • AWS JDBC Driver 2.3.2
  • Postgresql 42.5.4
  • Gradle 7
  • Java 11

You will progress through the following sections:

  1. Create a Gradle Spring Boot project
  2. Add the required Gradle dependencies
  3. Configure the AWS Advanced JDBC Driver

Pre-requisites

  • This tutorial uses the Aurora PostgreSQL database.

Step 1: Create a Gradle Project

Create a Gradle project with the following project hierarchy:

└───src
    └───main
        ├───java
        │   └───example
        │       ├───data
        │       │   ├───Book.java
        │       │   ├───BookRepository.java
        │       │   └───BookService.java
        │       └───spring
        │           ├───Config.java
        │           ├───LoadBalancedReaderDataSourceContext.java
        │           ├───RoutingDataSource.java
        │           ├───ShouldRetryTransactionException.java
        │           ├───SpringHibernateBalancedReaderTwoDataSourceExampleApplication.java
        │           ├───WithLoadBalancedDataSourceInterception.java
        │           └───WithLoadBalancedReaderDataSource.java
        └───resources
                └───application.yml

Note: this sample code assumes the target database contains a table named Book that can be generated using the SQL queries provided in src/main/resources/books.sql.

Step 2: Add the required Gradle Dependencies

In your build.gradle.kts, add the following dependencies.

dependencies {
   implementation("org.springframework.boot:spring-boot-starter-jdbc")
   implementation("org.springframework.retry:spring-retry")
   implementation("org.postgresql:postgresql")
   implementation("software.amazon.jdbc:aws-advanced-jdbc-wrapper:latest")
}

Please note that the sample code inside the AWS JDBC Driver project will use the dependency implementation(project(":aws-advanced-jdbc-wrapper")) instead of implementation("software.amazon.jdbc:aws-advanced-jdbc-wrapper:latest") as seen above.

Step 3: Configure Spring and Hibernate

Configure Spring to use the AWS JDBC Driver as the default datasource.

  1. In the application.yml, add new datasources for Spring:

    spring:
  datasource:
    writer-datasource:
      url: jdbc:aws-wrapper:postgresql://db-identifier.cluster-XYZ.us-east-2.rds.amazonaws.com:5432/test_db?wrapperProfileName=SF_F0
      username: dev_user
      password: dev_password
      driver-class-name: software.amazon.jdbc.Driver
      type: org.springframework.jdbc.datasource.SimpleDriverDataSource
    load-balanced-reader-datasource:
      url: jdbc:aws-wrapper:postgresql://db-identifier.cluster-ro-XYZ.us-east-2.rds.amazonaws.com:5432/test_db?wrapperProfileName=SF_F0&readerInitialConnectionHostSelectorStrategy=roundRobin
      username: dev_user
      password: dev_password
      driver-class-name: software.amazon.jdbc.Driver
      type: org.springframework.jdbc.datasource.SimpleDriverDataSource

  2. The datasources mentioned above do not use Hikari datasources which are the default for Spring 2+ applications. The AWS JDBC Driver manages its own internal connection pool (or several connection pools, if needed), which increases overall efficiency and helps facilitate failover support. All necessary configuration parameters are defined in SF_F0 configuration profile. Other configuration presets from SF_ family can be used as well. More details are available at Configuration Profiles and Configuration Presets.

    Optional configuration parameter readerInitialConnectionHostSelectorStrategy in connection string helps to setup a strategy selecting a reader node. Possible values are random, roundRobin and leastConnections. More details are available at Reader Selection Strategies.

  3. Configure Hibernate dialect:

    jpa:
 properties:
   hibernate:
     dialect: org.hibernate.dialect.PostgreSQLDialect

  4. [Optional] You can enable driver logging by adding the following to application.yml:

    logging:
   level:
     software:
       amazon:
         jdbc: INFO
         jdbc.states: INFO
     example: TRACE

For detailed logs use TRACE for software.amazon.jdbc package.

Start the application by running ./gradlew :springhibernatetwodatasource:bootRun in the terminal. You should see the application making a connection to the database and fetching data from the Book table.

Summary

This tutorial walks through the steps required to add and configure the AWS JDBC Driver to a simple Spring Boot and Hibernate application that load balances connections.