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Use Spring Data R2DBC with Azure Database for MySQL
Learn how to use Spring Data R2DBC with an Azure Database for MySQL database.
hangwan
07/22/2022
KarlErickson
article
devx-track-java, devx-track-azurecli, team=cloud_advocates, spring-cloud-azure, devx-track-extended-java

Use Spring Data R2DBC with Azure Database for MySQL

This article demonstrates creating a sample application that uses Spring Data R2DBC to store and retrieve information in Azure Database for MySQL by using the R2DBC implementation for MySQL from the r2dbc-mysql GitHub repository.

R2DBC brings reactive APIs to traditional relational databases. You can use it with Spring WebFlux to create fully reactive Spring Boot applications that use non-blocking APIs. It provides better scalability than the classic "one thread per connection" approach.

[!INCLUDE spring-data-prerequisites.md]

See the sample application

In this article, you'll code a sample application. If you want to go faster, this application is already coded and available at https://github.com/Azure-Samples/quickstart-spring-data-r2dbc-mysql.

Prepare the working environment

First, set up some environment variables by running the following commands:

export AZ_RESOURCE_GROUP=database-workshop
export AZ_DATABASE_NAME=<YOUR_DATABASE_NAME>
export AZ_LOCATION=<YOUR_AZURE_REGION>
export AZ_MYSQL_ADMIN_USERNAME=spring
export AZ_MYSQL_ADMIN_PASSWORD=<YOUR_MYSQL_ADMIN_PASSWORD>
export AZ_MYSQL_NON_ADMIN_USERNAME=spring-non-admin
export AZ_MYSQL_NON_ADMIN_PASSWORD=<YOUR_MYSQL_NON_ADMIN_PASSWORD>

Replace the placeholders with the following values, which are used throughout this article:

  • <YOUR_DATABASE_NAME>: The name of your MySQL server, which should be unique across Azure.
  • <YOUR_AZURE_REGION>: The Azure region you'll use. You can use eastus by default, but we recommend that you configure a region closer to where you live. You can see the full list of available regions by using az account list-locations.
  • <YOUR_MYSQL_ADMIN_PASSWORD> and <YOUR_MYSQL_NON_ADMIN_PASSWORD>: The password of your MySQL database server, which should have a minimum of eight characters. The characters should be from three of the following categories: English uppercase letters, English lowercase letters, numbers (0-9), and non-alphanumeric characters (!, $, #, %, and so on).

Next, create a resource group:

az group create \
    --name $AZ_RESOURCE_GROUP \
    --location $AZ_LOCATION \
    --output tsv

Create an Azure Database for MySQL instance and set up the admin user

The first thing you'll create is a managed MySQL server with an admin user.

Note

You can read more detailed information about creating MySQL servers in Create an Azure Database for MySQL server by using the Azure portal.

az mysql flexible-server create \
    --resource-group $AZ_RESOURCE_GROUP \
    --name $AZ_DATABASE_NAME \
    --location $AZ_LOCATION \
    --admin-user $AZ_MYSQL_ADMIN_USERNAME \
    --admin-password $AZ_MYSQL_ADMIN_PASSWORD \
    --yes \
    --output tsv

Configure a MySQL database

Create a new database called demo by using the following command:

az mysql flexible-server db create \
    --resource-group $AZ_RESOURCE_GROUP \
    --database-name demo \
    --server-name $AZ_DATABASE_NAME \
    --output tsv

Configure a firewall rule for your MySQL server

Azure Database for MySQL instances are secured by default. They have a firewall that doesn't allow any incoming connection.

You can skip this step if you're using Bash because the flexible-server create command already detected your local IP address and set it on MySQL server.

If you're connecting to your MySQL server from Windows Subsystem for Linux (WSL) on a Windows computer, you need to add the WSL host ID to your firewall. Obtain the IP address of your host machine by running the following command in WSL:

cat /etc/resolv.conf

Copy the IP address following the term nameserver, then use the following command to set an environment variable for the WSL IP Address:

export AZ_WSL_IP_ADDRESS=<the-copied-IP-address>

Then, use the following command to open the server's firewall to your WSL-based app:

az mysql flexible-server firewall-rule create \
    --resource-group $AZ_RESOURCE_GROUP \
    --name $AZ_DATABASE_NAME \
    --start-ip-address $AZ_WSL_IP_ADDRESS \
    --end-ip-address $AZ_WSL_IP_ADDRESS \
    --rule-name allowiprange \
    --output tsv

Create a MySQL non-admin user and grant permission

This step will create a non-admin user and grant all permissions on the demo database to it.

Note

You can read more detailed information about creating MySQL users in Create users in Azure Database for MySQL.

First, create a SQL script called create_user.sql for creating a non-admin user. Add the following contents and save it locally:

cat << EOF > create_user.sql
CREATE USER '$AZ_MYSQL_NON_ADMIN_USERNAME'@'%' IDENTIFIED BY '$AZ_MYSQL_NON_ADMIN_PASSWORD';
GRANT ALL PRIVILEGES ON demo.* TO '$AZ_MYSQL_NON_ADMIN_USERNAME'@'%';
FLUSH PRIVILEGES;
EOF

Then, use the following command to run the SQL script to create the non-admin user:

mysql -h $AZ_DATABASE_NAME.mysql.database.azure.com --user $AZ_MYSQL_ADMIN_USERNAME --enable-cleartext-plugin --password=$AZ_MYSQL_ADMIN_PASSWORD < create_user.sql

Now use the following command to remove the temporary SQL script file:

rm create_user.sql

[!INCLUDE spring-data-create-reactive.md]

Generate the application by using Spring Initializr

Generate the application on the command line by entering:

curl https://start.spring.io/starter.tgz -d dependencies=webflux,data-r2dbc -d baseDir=azure-database-workshop -d bootVersion=2.7.11 -d javaVersion=17 | tar -xzvf -

Add the reactive MySQL driver implementation

Open the generated project's pom.xml file to add the reactive MySQL driver from the r2dbc-mysql repository on GitHub.

After the spring-boot-starter-webflux dependency, add the following snippet:

<dependency>
  <groupId>io.asyncer</groupId>
  <artifactId>r2dbc-mysql</artifactId>
  <version>0.9.1</version>
</dependency>

Configure Spring Boot to use Azure Database for MySQL

Open the src/main/resources/application.properties file, and add:

logging.level.org.springframework.data.r2dbc=DEBUG

spring.r2dbc.url=r2dbc:pool:mysql://$AZ_DATABASE_NAME.mysql.database.azure.com:3306/demo?tlsVersion=TLSv1.2
spring.r2dbc.username=spring-non-admin
spring.r2dbc.password=$AZ_MYSQL_NON_ADMIN_PASSWORD

Replace the $AZ_DATABASE_NAME and $AZ_MYSQL_NON_ADMIN_PASSWORD variables with the values that you configured at the beginning of this article.

Note

For better performance, the spring.r2dbc.url property is configured to use a connection pool using r2dbc-pool.

You should now be able to start your application by using the provided Maven wrapper:

./mvnw spring-boot:run

Here's a screenshot of the application running for the first time:

:::image type="content" source="media/configure-spring-data-r2dbc-with-azure-mysql/create-mysql-01.png" alt-text="Screenshot of the running application." lightbox="media/configure-spring-data-r2dbc-with-azure-mysql/create-mysql-01.png":::

Create the database schema

[!INCLUDE spring-data-r2dbc-create-schema.md]

DROP TABLE IF EXISTS todo;
CREATE TABLE todo (id SERIAL PRIMARY KEY, description VARCHAR(255), details VARCHAR(4096), done BOOLEAN);

Stop the running application, and start it again. The application will now use the demo database that you created earlier, and create a todo table inside it.

./mvnw spring-boot:run

Here's a screenshot of the database table as it's being created:

:::image type="content" source="media/configure-spring-data-r2dbc-with-azure-mysql/create-mysql-02.png" alt-text="Screenshot of the creation of the database table." lightbox="media/configure-spring-data-r2dbc-with-azure-mysql/create-mysql-02.png":::

Code the application

Next, add the Java code that will use R2DBC to store and retrieve data from your MySQL server.

[!INCLUDE spring-data-r2dbc-create-application.md]

Here's a screenshot of these cURL requests:

:::image type="content" source="media/configure-spring-data-r2dbc-with-azure-mysql/create-mysql-03.png" alt-text="Screenshot of the cURL test." lightbox="media/configure-spring-data-r2dbc-with-azure-mysql/create-mysql-03.png":::

Congratulations! You've created a fully reactive Spring Boot application that uses R2DBC to store and retrieve data from Azure Database for MySQL.

[!INCLUDE spring-data-conclusion.md]

See also

For more information about Spring Data R2DBC, see Spring's reference documentation.

For more information about using Azure with Java, see Azure for Java developers and Working with Azure DevOps and Java.