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Introduction
In this article, we will learn how to use the Azure Migrate: App Containerization tool to migrate Java web apps (running on Apache Tomcat) to Azure Kubernetes Service (AKS). Existing apps can be easily containerized to Azure Kubernetes Service (AKS).
Prepare an Azure user account
Firstly, create a free account if you don't have an Azure subscription.
After setting up your subscription, you'll require an Azure user account with:
Azure subscription owner permissions
Permission to register apps for Azure Active Directory
Your subscription belongs to you if you recently created a free Azure account. Work with the owner to assign the following rights if you aren't the subscription's owner:
Search for "subscriptions" in the Azure search interface and then choose Subscriptions under Services.
Choose the subscription under which you wish to establish an Azure Migrate project on the Subscriptions page.
Select Access control (IAM).
To access the Add role assignment page, select Add > Add role assignment.
Assign the role as per your preference.
To register Azure Active Directory apps, you also require permissions on your Azure account.
Go to Azure Active Directory > Users > User Settings in the Azure portal.
Verify that Azure AD users may register applications under user settings (set to Yes by default).
If the "App registrations" setting is set to "No," ask the global administrator to grant the necessary permission.
Download and install the App Containerization tool
On a Windows machine, download the Azure Migrate: App Containerization installer.
Launch PowerShell in administrator mode, then change the directory to the installer's folder.
Use the command to execute the installation script.
.\AppContainerizationInstaller.ps1
Launch the App Containerization tool
Any device that can connect to the Windows computer running the App Containerization tool should open a browser and access the following tool URL: https://machine name or IP address: 44369. You might also choose the app shortcut on your desktop to launch the app from there.
If a warning appears suggesting that your connection is not private, click Advanced and decide to visit the website. The web interface employs a self-signed TLS/SSL certificate, which is why this warning is displayed.
Use the machine's local administrator account to log in at the sign-in page.
You can containerize Java web apps by using this option in Tomcat.
Choose Containers on Azure Kubernetes Service to identify the Azure destination service.
Sign in to Azure Account
Click to access your Azure account using login or sign in.
To log in to Azure, you require a device code. A modal window with the device code will appear when you click "Sign in".
To copy the device code and launch an Azure sign-in prompt in a new browser tab, select Copy code & sign in. Turn off the pop-up blocker in the browser if it doesn't appear.
Paste the device code into the new tab, then sign in with your Azure account credentials. Once the sign-in process is complete, you can exit the browser tab and go back to the online interface for the App Containerization tool.
Choose the Azure tenant you want to employ.
Indicate the desired Azure subscription.
Discover Java web applications
The App Containerization assistance tool attempts to locate any Java web apps (running on Apache Tomcat) on the application servers by establishing a remote connection to the application servers using the specified credentials.
Indicate the Java web application server's IP address, FQDN, and login information that should be used to connect to the server remotely for application discovery.
To ensure the credentials are correct and the application server can be reached from the program's system, click Validate. When validation is successful, the status column will read "Mapped".
To begin application discovery on the chosen application servers, click Continue.
You can choose the list of applications to containerize once application discovery has been completed.
To choose which programs to containerize, use the checkbox.
Name of the container: Give the target container for each chosen application a name. The tag should be given by the container name when used for a container image. For instance, you may enter appname:v1 as the target container name.
Parameterize application configurations
The configuration can be used as a deployment time parameter when it is parameterized. By doing this, you can customize this parameter when you deploy the application rather than having it fixed to a particular value in the container image. This choice is advantageous for parameters like database connection strings, for instance.
To examine the discovered setups, click App configurations.
To parameterize the detected application configurations, check the box.
After choosing the configurations to parameterize, click Apply.
Externalize file system dependencies
Other folders that your application utilizes can be added. Indicate whether or not they should be externalized through persistent volumes on an Azure file share or included in the container image for stateful apps that save state outside of the container or have other static material kept on the file system.
To view the discovered application folders, click Edit under App Folders. The detected application directories will be copied into the container image as they have been determined to be necessary artifacts for the program.
Select the folder paths to be added by clicking Add folders.
Provide comma (,) separated values if you want to add more than one folder to the same disc.
If you want the folders to be saved outside the container on a Persistent Volume, choose Persistent Volume as the storage option.
Review the application folders, then click Save.
To continue in the process of building container images, click Continue.
Build container image
Select Azure Container Registry: Choose an Azure Container Registry from the dropdown to be used for creating and storing the container images for the apps. Using the Create new registry option, you can use an existing Azure Container Registry or start from scratch.
Review the Dockerfile: At the start of the build stage, the Dockerfile required to create the container images for each chosen application is generated. To review the Dockerfile, click Review. Before beginning the build process, you can make any necessary adjustments to the Dockerfile in the review stage and save the modifications.
Configure Application Insights: Enable monitoring for Java programs running on App Service. The tool will install the Java standalone as a component of the container image. The Java agent will automatically gather many requests, dependencies, logs, and metrics for your application once it has been configured during deployment. These can be utilized for monitoring with Application Insights. All Java apps have this option turned on by default.
Trigger build process: Click Build after choosing the programs you want to create images for. Each application's container image creation will begin after you click create. The program monitors the build status and will allow you to move on to the following phase after the build has been completed.
Track build status: By selecting the Build in Progress link in the Status column, you can keep tabs on the status of the build phase. After you've started the construction process, it takes a few minutes before the connection becomes operational.
Click Continue to specify deployment settings once the build is finished.
Deploy the containerized app on AKS
After the container image has been created, our next step is to deploy the application as a container on Azure Kubernetes Service(AKS).
Select the Azure Kubernetes Service Cluster: Indicate the AKS cluster the program should be installed on.
• There needs to be a Linux node pool in the chosen AKS cluster.
• The cluster must be set up so pictures can be pulled from the Azure Container Registry chosen to house the images.
• You can choose to create one from the tool by clicking Establish a new AKS cluster. The utility will establish a Linux node pool for the AKS cluster it creates. The cluster will be set up such that it may get images from the previously established Azure Container Registry.
• After choosing the AKS cluster, press Continue.
Specify secret store and monitoring workspace: Indicate the secret store to be utilized for the application if you had chosen to parameterize application configurations. You can use Kubernetes Secrets or Azure Key Vault to manage your application secrets.
• Click Continue if you've chosen Kubernetes Secrets to manage your secrets.
• If you want to manage your application secrets using an Azure Key Vault, indicate the Azure Key Vault you want to utilize. By selecting build new from the tool, you may decide whether to create an Azure Key Vault if you don't already have one or want a new one. The tool will automatically grant the required rights to manage secrets using the Key Vault.
• You must specify the Application Insights resource to utilize if you choose to enable monitoring with Application Insights. If you have monitoring integration deactivated, this option wouldn't be available.
Specify Azure file share: Indicate the Azure file share that the Azure Migrate should utilize: App Containerization tool during the deployment process if you added extra folders and chose the Persistent Volume option. The program will construct new directories in this Azure file share to copy over the application folders set up for Persistent Volume storage. The program will clean up the Azure file share by erasing the directories it had generated once the application deployment is finished.
• By selecting Create new Storage Account and file share from the tool, you can decide whether you already have an Azure file share or would like to create a new one.
Application deployment configuration: After completing the procedures above, you must provide the application's deployment settings. To alter the deployment for the application, click Configure. You can give the following customizations during the configure step:
• Prefix string: Enter a prefix string that will be applied to the name of each resource produced for the containerized application in the AKS cluster.
• Set the number of application instances (pods) to execute in each container in a replica set.
• If the containerized application should be accessible from public networks, choose External as the load balancer type.
• Application Configuration: Provide the values for the current deployment for any parameterized application configurations.
• Storage: Indicate whether the volume should be shared among application instances or whether it should be initialized separately with each instance in the container for any application folders that were set for persistent volume storage. Every application folder is set to be shared by default on Persistent Volumes.
• To save the deployment configuration, click Apply.
• To deploy the application, click Continue.
Deploy the application: This tool will customize the Kubernetes deployment YAML for the application.
• Click review and customize the Kubernetes deployment YAML for the applications.
• Select apps which you want to deploy.
• Click Deploy to start deployment.
• After completion, you can check the Deployment status column to track the resources deployed for the application.
The Apache Software Foundation (ASF) created the Java Servlet Container, Tomcat, which is open-source. An extremely well-liked open-source relational database management system is MySQL.
How does the Tomcat server work?
A web container called Tomcat manages your servlets and their mappings. Tomcat checks the URL mappings after any request for a servlet is made to apache, and the result is generated in a way browsers can understand.
How is Apache Tomcat put to use?
One of Tomcat's connectors receives a request from a client. Tomcat routes this request to the proper Engine for processing. The range of Tomcat's search for the right Engine is constrained because these Engines are included within other elements like hosts and servers.
Can Apache and Tomcat run together?
Running Apache and Tomcat on the same computer is no problem. It's pretty common to run Tomcat on port 8080, run Apache on port 80/443, and use mod_proxy to allow Apache to serve apps hosted by Tomcat.
Can I utilize the Azure App service with Tomcat clustering?
The Azure App Service does not allow Tomcat clustering. Instead of requiring Tomcat-specific capabilities, you can configure and manage scalability and load balancing with Azure App Service. To make the session state accessible across replicas, you can store it in a different place.
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