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07 - Build a Spring Boot microservice using MySQL

This guide is part of the Azure Spring Cloud training

Build a classical Spring Boot application that uses JPA to access a MySQL database managed by Azure.

Create the application on Azure Spring Cloud

As in 02 - Build a simple Spring Boot microservice, create a specific weather-service application in your Azure Spring Cloud instance:

az spring-cloud app create -n weather-service

Configure the MySQL Server instance

After following the steps in Section 00, you should have an Azure Database for MySQL instance named sclabm-<unique string> in your resource group.

Before we can use it however, we will need to perform several tasks:

  1. Create a MySQL firewall rule to allow connections from our local environment.
  2. Create a MySQL firewall rule to allow connections from Azure Services. This will enable connections from Azure Spring Cloud.
  3. Create a MySQL database.

💡When prompted for a password, enter the MySQL password you specified when deploying the ARM template in Section 00.

💡The following scripts require jq (https://stedolan.github.io/jq/) to be installed if run locally, jq is already installed if running Cloud Shell

# Obtain the info on the MYSQL server in our resource group:
MYSQL_INFO=$(az mysql server list --query '[0]')
MYSQL_SERVERNAME=$(echo $MYSQL_INFO | jq -r .name)
MYSQL_USERNAME="$(echo $MYSQL_INFO | jq -r .administratorLogin)@${MYSQL_SERVERNAME}"
MYSQL_HOST="$(echo $MYSQL_INFO | jq -r .fullyQualifiedDomainName)"

# Create a firewall rule to allow connections from your machine:
MY_IP=$(curl whatismyip.akamai.com 2>/dev/null)
az mysql server firewall-rule create \
    --server-name $MYSQL_SERVERNAME \
    --name "connect-from-lab" \
    --start-ip-address "$MY_IP" \
    --end-ip-address "$MY_IP"

# Create a firewall rule to allow connections from Azure services:
az mysql server firewall-rule create \
    --server-name $MYSQL_SERVERNAME \
    --name "connect-from-azure" \
    --start-ip-address "0.0.0.0" \
    --end-ip-address "0.0.0.0"

# Create a MySQL database
az mysql db create \
    --resource-group $AZ_RESOURCE_GROUP \
    --name "azure-spring-cloud-training" \
    --server-name $MYSQL_SERVERNAME

# Display MySQL username (to be used in the next section)
echo "Your MySQL username is: ${MYSQL_USERNAME}"

Bind the MySQL database to the application

As we did for CosmosDB in the previous section, create a service binding for the MySQL database to make it available to Azure Spring Cloud microservices. In the Azure Portal:

  • Navigate to your Azure Spring Cloud instance
  • Click on Apps
  • Click on weather-service.
  • Click on "Service Bindings" and then on "Create Service Binding".
  • Populate the service binding fields as shown.
    • The username will be displayed in last line of output from the section above.
    • The password is the one you specified in section 0. The default value is super$ecr3t.
  • Click on Create to create the database binding

MySQL Service Binding

Create a Spring Boot microservice

Now that we've provisioned the Azure Spring Cloud instance and configured the service binding, let's get the code for weather-service ready. The microservice that we create in this guide is available here.

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

curl https://start.spring.io/starter.tgz -d dependencies=web,data-jpa,mysql,cloud-eureka,cloud-config-client -d baseDir=weather-service -d bootVersion=2.3.8 -d javaVersion=1.8 | tar -xzvf -

We use the Spring Web, Spring Data JPA, MySQL Driver, Eureka Discovery Client and the Config Client components.

Add Spring code to get the data from the database

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

package com.example.demo;

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

@Entity
public class Weather {

    @Id
    private String city;

    private String description;

    private String icon;

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getDescription() {
        return description;
    }

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

    public String getIcon() {
        return icon;
    }

    public void setIcon(String icon) {
        this.icon = icon;
    }
}

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

package com.example.demo;

import org.springframework.data.repository.CrudRepository;

public interface WeatherRepository extends CrudRepository<Weather, String> {
}

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

package com.example.demo;

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

@RestController
@RequestMapping(path="/weather")
public class WeatherController {

    private final WeatherRepository weatherRepository;

    public WeatherController(WeatherRepository weatherRepository) {
        this.weatherRepository = weatherRepository;
    }

    @GetMapping("/city")
    public @ResponseBody Weather getWeatherForCity(@RequestParam("name") String cityName) {
        return weatherRepository.findById(cityName).get();
    }
}

Add sample data in MySQL

In order to have Hibernate automatically create your database, open up the src/main/resources/application.properties file and add:

spring.jpa.hibernate.ddl-auto=create

Then, in order to have Spring Boot add sample data at startup, create a src/main/resources/import.sql file and add:

INSERT INTO `azure-spring-cloud-training`.`weather` (`city`, `description`, `icon`) VALUES ('Paris, France', 'Very cloudy!', 'weather-fog');
INSERT INTO `azure-spring-cloud-training`.`weather` (`city`, `description`, `icon`) VALUES ('London, UK', 'Quite cloudy', 'weather-pouring');

The icons we are using are the ones from https://materialdesignicons.com/ - you can pick their other weather icons if you wish.

Deploy the application

You can now build your "weather-service" project and send it to Azure Spring Cloud:

cd weather-service
./mvnw clean package -DskipTests
az spring-cloud app deploy -n weather-service --jar-path target/demo-0.0.1-SNAPSHOT.jar
cd ..

Test the project in the cloud

  • Go to "Apps" in your Azure Spring Cloud instance.
    • Verify that weather-service has a Discovery status which says UP(1),DOWN(0). This shows that it is correctly registered in the Spring Cloud Service Registry.
    • Select weather-service to have more information on the microservice.
  • Copy/paste the "Test Endpoint" that is provided. You might have to click on See more to find it.

You can now use cURL to test the /weather/city endpoint. For example, to test for Paris, France city, append to the end of the test endpoint: /weather/city?name=Paris%2C%20France.

{"city":"Paris, France","description":"Very cloudy!","icon":"weather-fog"}

If you need to check your code, the final project is available in the "weather-service" folder.

⬅️ Previous guide: 06 - Build a reactive Spring Boot microservice using Cosmos DB

➡️ Next guide: 08 - Build a Spring Cloud Gateway