Build a Spring Boot microservice

In this module, we'll build a cloud-enabled Spring Boot microservice. It uses a Spring Cloud service registry and a Spring Cloud Config Server, which are both managed and supported by Azure Spring Apps.

This microservice uses Spring Data JPA to read and write data from an Azure database for MySQL database:

• Azure Spring Apps automatically binds that database to our service.
• Azure database for MySQL is a fully managed version of MySQL, running on Azure.

Create the application on Azure Spring Apps

Create a specific todo-service application in your Azure Spring Apps instance:

az spring app create --name todo-service --resource-group "$RESOURCE_GROUP_NAME" --service "$SPRING_CLOUD_NAME" --runtime-version Java_17

Create a MySQL database

Now create an Azure database for MySQL:

az mysql server create \
    --name ${SPRING_CLOUD_NAME}-mysql \
    --resource-group "$RESOURCE_GROUP_NAME" \
    --sku-name B_Gen5_1 \
    --storage-size 5120 \
    --admin-user "spring"

This operation can take a few minutes, and outputs a JSON document: copy the password attribute in that document, as we'll use it later.

Now create a todos database in that server, and open up its firewall so that Azure Spring Apps can access it:

az mysql db create \
    --name "todos" \
    --server-name ${SPRING_CLOUD_NAME}-mysql

az mysql server firewall-rule create \
    --name ${SPRING_CLOUD_NAME}-mysql-allow-azure-ip \
    --resource-group "$RESOURCE_GROUP_NAME" \
    --server ${SPRING_CLOUD_NAME}-mysql \
    --start-ip-address "0.0.0.0" \
    --end-ip-address "0.0.0.0"

Once this operation completes, you can have a look at what was created in the resource group that you created for this workshop.

Bind the MySQL database to the application

Azure Spring Apps can automatically bind the MySQL database we created to our microservice.

1. Navigate to your Azure Spring Apps instance.

2. Select Apps.

3. Select the todo-service application.

4. Select Service Connector and then choose + Create.

   1. For Service type, select DB for MySQL single server.
   2. Specify a connection name, for example mysql_todos.
   3. Verify that the correct subscription is shown.
   4. Choose the MySQL server created in the preceding steps.
   5. Select the MySQL database created earlier.
   6. Select SpringBoot as the Client type.
   7. Select the Next: Authentication button.

5. On the Authentication page, verify that Connection string is selected.

6. Select Continue with...Database credentials and fill in the username and password fields. The username is "spring" and the password is the password attribute that we copied earlier.

   Note

   If you forget your password, you can reset it by using az mysql server update -n ${SPRING_CLOUD_NAME}-mysql -g "$RESOURCE_GROUP_NAME" -p <new-password>

7. Verify that Configure firewall rules to enable access to target service is selected.

8. Click on Next: Review + Create.

9. After the Validation passed message appears, select the Create button to create the Service Connector.

Create a Spring Boot microservice

Now that we provisioned the Azure Spring Apps instance and configured the service binding, let's get the code for todo-service ready.

To create our microservice, we'll use https://start.spring.io with the command line:

curl https://start.spring.io/starter.tgz -d type=maven-project -d dependencies=web,mysql,data-jpa,cloud-eureka,cloud-config-client -d baseDir=todo-service -d bootVersion=3.1.5.RELEASE -d javaVersion=17 | tar -xzvf -

Add Spring code to manage data using Spring Data JPA

Next to the DemoApplication class, create a Todo JPA entity:

package com.example.demo;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Todo {

    public Todo() {
    }

    public Todo(String description, boolean done) {
        this.description = description;
        this.done = done;
    }

    @Id
    @GeneratedValue
    private Long id;

    private String description;

    private boolean done;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public boolean isDone() {
        return done;
    }

    public void setDone(boolean done) {
        this.done = done;
    }
}

Then, create a Spring Data JPA repository to manage this entity, called TodoRepository:

package com.example.demo;

import org.springframework.data.jpa.repository.JpaRepository;

public interface TodoRepository extends JpaRepository<Todo, Long> {
}

And finish coding this application by adding a Spring MVC controller called TodoController:

package com.example.demo;

import org.springframework.web.bind.annotation.*;

import javax.annotation.PostConstruct;
import java.util.Arrays;

@RestController
public class TodoController {

    private final TodoRepository todoRepository;

    public TodoController(TodoRepository todoRepository) {
        this.todoRepository = todoRepository;
    }

    @PostConstruct
    public void init() {
        todoRepository.saveAll(Arrays.asList(
                new Todo("First item", true),
                new Todo("Second item", true),
                new Todo("Third item", false)));
    }

    @GetMapping("/")
    public Iterable<Todo> getTodos() {
        return todoRepository.findAll();
    }
}

Configure Spring Boot to create the database tables

In order to automatically generate the database tables when the application is deployed, add this line to your src/main/resources/application.properties configuration file:

spring.jpa.hibernate.ddl-auto=create-drop

Deploy the application

You can now build your todo-service project and send it to Azure Spring Apps:

cd todo-service
./mvnw clean package -DskipTests
az spring app deploy --name todo-service --service "$SPRING_CLOUD_NAME" --resource-group "$RESOURCE_GROUP_NAME" --artifact-path target/demo-0.0.1-SNAPSHOT.jar
cd ..

If you want to check the logs of the application, in case something fails, you can use the az spring app logs command:

az spring app logs --name todo-service --service "$SPRING_CLOUD_NAME" --resource-group "$RESOURCE_GROUP_NAME" -f

Test the project in the cloud

Now that the application is deployed, it's time to test it!

1. In the Azure portal, go to Apps in your Azure Spring Apps instance.
   1. Verify todo-service has a Registration status that says 0/1. This information shows that it's correctly registered in the Spring Cloud service registry.
   2. Select todo-service to have more information on the microservice.
2. Copy/paste the "Test Endpoint" that is provided.

You can now use cURL to test the endpoint. Your test command should look like:

curl https://primary:XXXXXXXXXXXXXXXXXXXXXXXXXXXXX@azure-spring-cloud-workshop.test.azuremicroservices.io/todo-service/default/

And the result of this command should be the three items that were previously inserted in the MySQL database:

[{"id":"1","description":"First item","done":true},{"id":"2","description":"Second item","done":true},{"id":"3","description":"Third item","done":false}]