H2 Database Integration with Spring Boot Microservices

October 27, 2025

This guide explains how to integrate H2 database with Spring Boot microservices for lightweight development and testing.

1. Add Dependencies

In each microservice pom.xml:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>com.h2database</groupId>
  <artifactId>h2</artifactId>
</dependency>

2. Configure H2

In application.properties of a microservice:

spring.datasource.url=jdbc:h2:mem:service_db
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=update
spring.h2.console.enabled=true

This sets up an in-memory DB per microservice.

3. Create an Entity

@Entity
public class Order {
  @Id @GeneratedValue
  private Long id;
  private String product;
  private int quantity;
}

4. Repository

public interface OrderRepository extends JpaRepository<Order, Long> {}

5. REST Controller

@RestController
@RequestMapping("/orders")
public class OrderController {
  @Autowired private OrderRepository repo;

  @PostMapping
  public Order save(@RequestBody Order order) {
    return repo.save(order);
  }

  @GetMapping
  public List<Order> findAll() {
    return repo.findAll();
  }
}

6. Running Multiple Microservices

Each service can have its own H2 DB.
For example:

OrderService → jdbc:h2:mem:order_db
CustomerService → jdbc:h2:mem:customer_db

They run independently and are isolated for testing.