Tutorial: Build a Tomcat web app with Azure App Service on Linux and MySQL

• An Azure account with an active subscription. If you don't have an Azure account, you can create one for free.
• A GitHub account. you can also get one for free.
• Knowledge of Java with Tomcat development.
• (Optional) To try GitHub Copilot, a GitHub Copilot account. A 30-day trial is available.

• An Azure account with an active subscription. If you don't have an Azure account, you can create one.
• Azure Developer CLI installed.
• Knowledge of Java with Tomcat development.
• (Optional) To try GitHub Copilot, a GitHub Copilot account. A 30-day trial is available.

2. Create App Service and MySQL

First, you create the Azure resources. The steps used in this tutorial create a set of secure-by-default resources that include App Service and Azure Database for MySQL. For the creation process, you specify:

• The Name for the web app. It's used as part of the DNS name.
• The Region to run the app physically in the world. It's also used as part of the DNS name for your app.
• The Runtime stack for the app. It's where you select the version of Java to use for your app.
• The Hosting plan for the app. It's the pricing tier that includes the set of features and scaling capacity for your app.
• The Resource Group for the app. A resource group lets you group (in a logical container) all the Azure resources needed for the application.

Sign in to the Azure portal and follow these steps to create your Azure App Service resources.

1. In the Azure portal:

   • In the search bar at the top, enter app service.
   • Under the Services heading, select App Service.
   • Select Create > Web App.

   You can also go directly to the creation wizard.

2. In the Create Web App page, on the Basics tab, fill out the form as follows:

   • Resource Group: Select Create new and use a name of msdocs-tomcat-mysql-tutorial.
   • Name: msdocs-tomcat-mysql-XYZ, where XYZ is any three random characters.
   • Runtime stack: Java 25.
   • Java web server stack: Apache Tomcat 11.0.
   • Operating System: Linux.
   • Region: Any Azure region near you.
   • Pricing plan: Basic. When you're ready, you can scale up to a production pricing tier.

3. Select the Database tab and configure the database:

   • Select Create a Database.
   • In Engine, select MySQL - Flexible Server. Azure Database for MySQL - Flexible Server is a fully managed MySQL database as a service on Azure, compatible with the latest community editions.
   • Don't select Create an Azure Cache for Redis.

4. Select Review + create. After validation completes, select Create.

5. When deployment finishes, select the Go to resource button. You're taken directly to the App Service app.

The following resources are created:

• Resource group: The container for all the created resources.
• App Service plan: Defines the compute resources for App Service. A Linux plan in the Basic tier is created.
• App Service: Represents your app and runs in the App Service plan.
• Virtual network: Integrated with the App Service app and isolates back-end network traffic.
• Azure Database for MySQL Flexible Server: Accessible only from the virtual network. A database and a user are created for you on the server.
• Private DNS zones: Enable DNS resolution of the database server in the virtual network.

Having issues? Check the Troubleshooting section.

3. Confirm JNDI data source

If your app settings contain a valid JDBC connection string for Oracle, SQL Server, PostgreSQL, or MySQL, and the app setting WEBSITE_AUTOCONFIGURE_DATABASE is set to true, App Service adds a Java Naming and Directory Interface (JNDI) data source for it in the Tomcat server's context.xml file. In this step, you add this app setting, then use the SSH connection to the app container to verify the JNDI data source. In the process, you learn how to access the SSH shell for the Tomcat container.

Having issues? Check the Troubleshooting section.

6. Browse to the app

Having issues? Check the Troubleshooting section.

7. Stream diagnostic logs

Azure App Service captures all messages output to the console to help you diagnose issues with your application. The sample application includes standard Log4j logging statements to demonstrate this capability, as shown in the following snippet:

@WebServlet(urlPatterns = "/")
public class ViewServlet extends HttpServlet {
    private static Logger logger = LogManager.getLogger(ViewServlet.class.getName());

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        logger.info("GET /");

        EntityManagerFactory emf = (EntityManagerFactory) req.getServletContext().getAttribute("EMFactory");

Learn more about logging in Java apps in the series on Enable Azure Monitor OpenTelemetry for .NET, Node.js, Python, and Java applications.

Having issues? Check the Troubleshooting section.

8. Clean up resources

When you're finished, you can delete all of the resources from your Azure subscription by deleting the resource group.

2. Create Azure resources and deploy a sample app

In this step, you create the Azure resources and deploy a sample app to App Service on Linux. The steps used in this tutorial create a set of secure-by-default resources that include App Service and Azure Database for MySQL.

The dev container already has the Azure Developer CLI (AZD).

1. From the repository root, run azd init.

   azd init --template tomcat-app-service-mysql-infra .
   

2. When prompted, give the following answers:

   Question	Answer
   The current directory is not empty. Would you like to initialize a project here in '<your-directory>'?	Y
   What would you like to do with these files?	Keep my existing files unchanged
   Enter a new environment name	Type a unique name. The AZD template uses this name as part of the DNS name of your web app in Azure (<app-name>-<hash>.chinacloudsites.cn). Alphanumeric characters and hyphens are allowed.

3. Sign into Azure by running the azd auth login command and following the prompt:

   azd auth login
   

4. Create the necessary Azure resources and deploy the app code with the azd up command. Follow the prompt to select the desired subscription and location for the Azure resources.

   azd up
   

   The azd up command takes about 10 minutes to complete. It also compiles and deploys your application code, but you modify your code later to work with App Service. While it's running, the command provides messages about the provisioning and deployment process, including a link to the deployment in Azure. When it finishes, the command also displays a link to the deploy application.

   This AZD template contains files (azure.yaml and the infra directory) that generate a secure-by-default architecture with the following Azure resources:

   • Resource group: The container for all the created resources.
   • App Service plan: Defines the compute resources for App Service. A Linux plan in the B1 tier is created.
   • App Service: Represents your app and runs in the App Service plan.
   • Virtual network: Integrated with the App Service app and isolates back-end network traffic.
   • Azure Database for MySQL Flexible Server: Accessible only from the virtual network through the DNS zone integration. A database is created for you on the server.
   • Azure Managed Redis: Accessible only from within the virtual network.
   • Private endpoints: Access endpoints for the key vault and the Managed Redis instance in the virtual network.
   • Private DNS zones: Enable DNS resolution of the key vault, the database server, and the Managed Redis instance in the virtual network.
   • Log Analytics workspace: Acts as the target container for your app to ship its logs, where you can also query the logs.
   • Key vault: Used to keep your database password the same when you redeploy with AZD.

   Once the command finishes creating resources and deploying the application code the first time, the deployed sample app doesn't work yet because you must make small changes to make it connect to the database in Azure.

Having issues? Check the Troubleshooting section.

3. Verify connection strings

The AZD template you use generated the connectivity variables for you already as app settings and outputs the them to the terminal for your convenience. App settings are one way to keep connection secrets out of your code repository.

1. In the AZD output, find the app setting AZURE_MYSQL_CONNECTIONSTRING. Only the setting names are displayed. They look like this in the AZD output:

    App Service app has the following connection strings:
            - AZURE_MYSQL_CONNECTIONSTRING
            - AZURE_REDIS_CONNECTIONSTRING
            - AZURE_KEYVAULT_RESOURCEENDPOINT
            - AZURE_KEYVAULT_SCOPE
    

   AZURE_MYSQL_CONNECTIONSTRING contains the connection string to the MySQL database in Azure. You need to use it in your code later.

2. For your convenience, the AZD template shows you the direct link to the app's app settings page. Find the link and open it in a new browser tab.

   If you add an app setting that contains a valid Oracle, SQL Server, PostgreSQL, or MySQL connection string, App Service adds it as a Java Naming and Directory Interface (JNDI) data source in the Tomcat server's context.xml file.

Having issues? Check the Troubleshooting section.

4. Confirm JNDI data source

In this step, you use the SSH connection to the app container to verify the JNDI data source in the Tomcat server. In the process, you learn how to access the SSH shell for the Tomcat container.

1. In the AZD output, find the URL for the SSH session and navigate to it in the browser. It looks like this in the output:

    Open SSH session to App Service container at: <URL>
    

2. In the SSH terminal, run cat /usr/local/tomcat/conf/context.xml. You should see that a JNDI resource called jdbc/AZURE_MYSQL_CONNECTIONSTRING_DS was added. You use this data source later. App Service automatically creates this data source because the AZD template sets the app setting WEBSITE_AUTOCONFIGURE_DATABASE to true.

   

Having issues? Check the Troubleshooting section.

5. Modify sample code and redeploy

Having issues? Check the Troubleshooting section.

6. Browse to the app

1. In the AZD output, find the URL of your app and navigate to it in the browser. The URL looks like this in the AZD output:

    Deploying services (azd deploy)
   
      (✓) Done: Deploying service web
      - Endpoint: <URL>
    

2. Add a few tasks to the list.

   

   Congratulations, you're running a web app in Azure App Service, with secure connectivity to Azure Database for MySQL.

Having issues? Check the Troubleshooting section.

7. Stream diagnostic logs

Azure App Service can capture console logs to help you diagnose issues with your application. For convenience, the AZD template already enabled logging to the local file system and is shipping the logs to a Log Analytics workspace.

The sample application includes standard Log4j logging statements to demonstrate this capability, as shown in the following snippet:

@WebServlet(urlPatterns = "/")
public class ViewServlet extends HttpServlet {
    private static Logger logger = LogManager.getLogger(ViewServlet.class.getName());

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        logger.info("GET /");

        EntityManagerFactory emf = (EntityManagerFactory) req.getServletContext().getAttribute("EMFactory");

In the AZD output, find the link to stream App Service logs and navigate to it in the browser. The link looks like this in the AZD output:

Stream App Service logs at: <URL>

Learn more about logging in Java apps in the series on Enable Azure Monitor OpenTelemetry for .NET, Node.js, Python, and Java applications.

Having issues? Check the Troubleshooting section.

8. Clean up resources

To delete all Azure resources in the current deployment environment, run azd down and follow the prompts.

azd down