How to Migrate a Spring Boot JPA App to Quarkus for Faster Startup

Quarkus is a hot Java application framework positioned as a lightweight microservice framework, offering excellent container integration, faster startup, lower memory consumption, and shorter response times compared to traditional frameworks like Spring Boot.

This article demonstrates how to migrate a Spring Boot application to Quarkus.

Spring Boot Sample Application

Using JPA to perform CRUD operations, the basic code is as follows:

Maven dependencies

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

JPA CRUD

public interface DemoUserDao extends CrudRepository<DemoUser, Long> {
}

Migration to Quarkus

quarkus-bom manages all Quarkus plugin Maven version information; after adding it, individual dependencies no longer need version definitions.

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>io.quarkus</groupId>
      <artifactId>quarkus-bom</artifactId>
      <version>1.10.5.Final</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

Migrate spring-web and spring-data-jpa to the Quarkus stack.

<dependency>
  <groupId>io.quarkus</groupId>
  <artifactId>quarkus-spring-data-jpa</artifactId>
</dependency>
<dependency>
  <groupId>io.quarkus</groupId>
  <artifactId>quarkus-spring-web</artifactId>
</dependency>

Configuration file adjustments (still in application.yml)

quarkus.datasource.db-kind=mysql
quarkus.datasource.jdbc.driver=com.mysql.cj.jdbc.Driver
quarkus.datasource.username=root
quarkus.datasource.password=root
quarkus.datasource.jdbc.url=jdbc:mysql://localhost:3306/pig_demo?useUnicode=true&characterEncoding=utf8&autoReconnect=true&rewriteBatchedStatements=TRUE

Main method adjustment to implement QuarkusApplication and keep the service running with Quarkus.waitForExit().

@QuarkusMain
public class SimpleApplication implements QuarkusApplication {
  public static void main(String[] args) {
    Quarkus.run(SimpleApplication.class, args);
  }
  @Override
  public int run(String... args) {
    Quarkus.waitForExit();
    return 0;
  }
}

Running the Application

The main method starts the application and prints the Quarkus banner.

__  ____  __  _____   ___  __ ____  ______
--/ __ \/ / / / _ | /_  \/ //_/ / / / __/
-/ /_/ / /_/ / __ |/ , _/,< /_/_ /\ 
--\___\_\____/_/ |_/_/|_/_/|_|\____/___/
2021-01-12 22:31:46,341 INFO  [io.qua.arc.pro.BeanProcessor] (build-21) Found unrecommended usage of private members (use package-private instead) in application beans:
 - @Inject field com.example.simple.controller.DemoController#userDao
2021-01-12 22:31:48,702 INFO  [io.quarkus] (Quarkus Main Thread) Quarkus 1.10.5.Final on JVM started in 4.613s. Listening on: http://localhost:8080
2021-01-12 22:31:48,703 INFO  [io.quarkus] (Quarkus Main Thread) Profile dev activated. Live Coding activated.
2021-01-12 22:31:48,703 INFO  [io.quarkus] (Quarkus Main Thread) Installed features: [agroal, cdi, hibernate-orm, hibernate-orm-panache, mutiny, narayana-jta, resteasy, resteasy-jackson, smallrye-context-propagation, spring-data-jpa, spring-di, spring-web]

It is important that the installed features are displayed.

Installed features: [agroal, cdi, hibernate-orm, hibernate-orm-panache, mutiny, narayana-jta, resteasy, resteasy-jackson, smallrye-context-propagation, spring-data-jpa, spring-di, spring-web]

Extension: Actuator Monitoring Migration

Add the following dependency

<dependency>
  <groupId>io.quarkus</groupId>
  <artifactId>quarkus-smallrye-health</artifactId>
</dependency>

Specify the health endpoint path

quarkus.smallrye-health.root-path=/actuator/health

Test the health endpoint

curl http://localhost:8080/actuator/health
{
  "status": "UP",
  "checks": [
    {
      "name": "Database connections health check",
      "status": "UP"
    }
  ]
}

Extension: Flyway Migration

Add the Quarkus Flyway plugin

<dependency>
  <groupId>io.quarkus</groupId>
  <artifactId>quarkus-flyway</artifactId>
</dependency>

Set the plugin to migrate at start

quarkus.flyway.migrate-at-start=true