Deploying WAR based Java applications with CI/CD (Azure DevOps) on App Service Windows

12 minute read | By Prakash Matte

In this blog post we’ll cover some examples of how to deploy war based applications to Windows App Service using Azure DevOps.

Overview

This section will cover CI/CD deployment for war-based applications - this is for Blessed Tomcat images, which will act as our Web Container for our war. With this image, you still have the option to choose your Java major version, as well as Apache Tomcat major and minor version - but the premise is that we’re deploying a war file into a Tomcat container, which Tomcat itself will run.

Below is a configuration reference from the portal:

This is not the same as running a Java SE “Blessed” Image which requires this to be an executable war with an embedded Web Server.

This post will also include deployment differences for Maven and Gradle.

Local Development

Configuring for Maven

Go to Spring Initializr and create the application with the following properties:
- Project: Maven
- Language: Java
- Spring Boot: 3.4.0 (SNAPSHOT)
- Project Metadata: Fill this as fits your needs
- Packaging: War
- Java: 17

For Dependencies, go to Add Dependencies and choose Spring Web. Click Generate after this, which will download a zip which we’ll extract into a project workspace.

After downloading the zip, extract it on your local machine and cd into the folder with the source code.
In a terminal, run either of the following:
- If Maven is on $PATH, run mvn spring-boot:run relative to the pom.xml.
- If Maven is not on $PATH, run ./mvnw spring-boot:run relative to the pom.xml

NOTE: This assumes you have Java 17 locally. Maven needs to point to a Java 17 installation as well. If you’re unsure to what Maven is using, use mvn -v.

After running the above command, you should see some output like the below in your terminal:

2024-11-03T21:01:16.889-06:00  INFO 28988 --- [azure] [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2024-11-03T21:01:16.889-06:00  INFO 28988 --- [azure] [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.31]       
2024-11-03T21:01:16.966-06:00  INFO 28988 --- [azure] [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2024-11-03T21:01:16.967-06:00  INFO 28988 --- [azure] [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1007 ms
2024-11-03T21:01:17.328-06:00  INFO 28988 --- [azure] [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port 8080 (http) with context path '/'
2024-11-03T21:01:17.346-06:00  INFO 28988 --- [azure] [           main] com.devops.azure.AzureApplication        : Started AzureApplication in 1.936 seconds (process running for 2.302)

Browsing to localhost:8080 should show a Whitelabel Error Page, which is expected, since we have no Controllers serving our root path.

Let’s add a Controller and model to show at the REST URL when hitting /greeting. Under your project src, relative to your entrypoint .java file, create a controller and a model. Let’s name is GreetingController.java and Greeting.java. The project structure should look like this:

| - src
|   | - main
|       | - java
|           | - com
|               | - devops
|                   | - azure
|                       | GreetingController.java
|                       | Greeting.java

Add the following code to GreetingController.java

package com.devops.azure;

import java.util.concurrent.atomic.AtomicLong;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {

	private static final String template = "Hello, %s!";
	private final AtomicLong counter = new AtomicLong();

	@GetMapping("/greeting")
	public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
		return new Greeting(counter.incrementAndGet(), String.format(template, name));
	}
}

Add the following code to Greeting.java

package com.devops.azure;

public record Greeting(long id, String content) { }

Restart the application. Refresh the browser, we should now see the below output at /greeting:

Push this code to a repository of your choosing to use later on for the DevOps section.

Configuring for Gradle

Go to Spring Initializr and create the application with the following properties:
- Project: Gradle - Groovy / Gradle - Kotlin (I selected Gradle - Groovy)
- Language: Java
- Spring Boot: 3.4.0 (SNAPSHOT)
- Project Metadata: Fill this as fits your needs
- Packaging: War
- Java: 17

For Dependencies, go to Add Dependencies and choose Spring Web. Click Generate after this, which will download a zip which we’ll extract into a project workspace.

After downloading the zip, extract it on your local machine and cd into the folder with the source code.
In a terminal, run ./gradlew bootRun to start the Spring Boot application. You should see the same output above as discussed in th Maven section.

DevOps

Prerequisites:

If not done so already, create an Azure DevOps Organization.
Next, create a Azure DevOps Project to host our pipeline after this.

Creating the pipeline:

In your Azure DevOps project go to:

Create azure-pipleines.yml
Pipelines -> Pipelines -> New Pipeline -> Azure DevOps
Select the repository that is hosting the code
Select the classification (Production / Non-production) -> assign a service -> Configure Pipeline
Select the Existing Azure Pipelines YAML file and browse azure-pipelines.yml (use the templates provided in the following Maven / Gradle sections) from your project:

Maven

# Maven package Java project Web App to Windows on Azure
# Build your Java project and deploy it to Azure as a Windows web app
# Add steps that analyze code, save build artifacts, deploy, and more:
# https://docs.microsoft.com/azure/devops/pipelines/languages/java

trigger:
- main

variables:

  # Azure Resource Manager connection created during pipeline creation
  azureSubscription: 'sc deploy to app service'

  # Web app name
  webAppName: 'myapp'

  # Environment name
  environmentName: 'myapp'

  # Agent VM image name
  vmImageName: 'ubuntu-latest'

stages:
- stage: Build
  displayName: Build stage
  jobs:
  - job: MavenPackageAndPublishArtifacts
    displayName: Maven Package and Publish Artifacts
    pool:
      vmImage: $(vmImageName)

    steps:
    - task: Maven@3
      displayName: 'Maven Package'
      inputs:
        mavenPomFile: 'pom.xml'
        # We add jdkVersionOption to point to Java 17 for Maven
        jdkVersionOption: 1.17

    - task: CopyFiles@2
      displayName: 'Copy Files to artifact staging directory'
      inputs:
        SourceFolder: '$(System.DefaultWorkingDirectory)'
        Contents: '**/target/*.?(war|jar)'
        TargetFolder: $(Build.ArtifactStagingDirectory)

    - upload: $(Build.ArtifactStagingDirectory)
      artifact: drop

- stage: Deploy
  displayName: Deploy stage
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: DeployWindowsWebApp
    displayName: Deploy Windows Web App
    environment: $(environmentName)
    pool:
      vmImage: $(vmImageName)
    strategy:
      runOnce:
        deploy:
          steps:
          - task: AzureWebApp@1
            displayName: 'Azure Web App Deploy: myapp'
            inputs:
              azureSubscription: $(azureSubscription)
              appType: webApp
              appName: $(webAppName)
              package: '$(Pipeline.Workspace)/drop/**/target/*.?(war|jar)'
              # IMPORTANT: If you don't add this it will deploy to a context named after your WAR
              # ex. yoursite.azurewebsites.net/azure-0.0.1-SNAPSHOT/
              customDeployFolder: 'ROOT'

Note Make sure to Authorize the pipeline for deployment. Click into the pipeline to view and permit this. This should be a one time operation.

Once the build was succesful from Azure DevOps pipeline, you could validate the deployment at the following two places from App Service.

Go to portal.azure.com -> App Service -> Deployment Center

Go to portal.azure.com -> App Service -> Advanced Tools -> Debug Console -> CMD

At this point after deployment, we should be able to browse our application on Azure.

You can view the Maven task documentation for further configuration here.

Azure DevOps - Why am I getting a 404 after deployment?

If you’re following along with the above, you should be able to get a pipeline quickly spun up with a succesful deployment. However, if you are expecting your site content to show up on the site’s root path (“/”) but did not add the customDeployFolder property (seen above), you may see this 404 after deployment:

You’ll see that when this deployment API is used it creates a webapps folder under wwwroot containing our exploded war:

This is because, by default, the API’s used in this deployment task pass the name of our war to the name parameter in the War Deploy URI being called. Therefore, if your war isn’t named ROOT, it will always deploy to a different context named after your war file.

This is opposed to the OneDeploy API being used on deployment methods such as the Azure CLI or the Maven Plugin which, under the hood, rename our war (or jar) to app.war and deploy directly to wwwroot instead of wwwroot/webapps. This in turn is mapped directly to the root context (“/”).

Another quick way to solve this, aside from using the customDeployFolder property is to add the <finalName></finalName> element to the <build></build> section of your pom.xml. Such as:

<build>
	<plugins>
		<plugin>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-maven-plugin</artifactId>
		</plugin>
	</plugins>
	<finalName>ROOT</finalName>
</build>

This will package the war with the name defined here and is what will be passed to the name parameter described above.

Gradle

# Maven package Java project Web App to Windows on Azure
# Build your Java project and deploy it to Azure as a Windows web app
# Add steps that analyze code, save build artifacts, deploy, and more:
# https://docs.microsoft.com/azure/devops/pipelines/languages/java

trigger:
- main

variables:

  # Azure Resource Manager connection created during pipeline creation
  azureSubscription: 'sc deploy to app service'

  # Web app name
  webAppName: 'myapp'

  # Environment name
  environmentName: 'myapp'

  # Agent VM image name
  vmImageName: 'ubuntu-latest'

stages:
- stage: Build
  displayName: Build stage
  jobs:
  - job: GradlePackageAndPublishArtifacts
    displayName: Gradle Package and Publish Artifacts
    pool:
      vmImage: $(vmImageName)

    steps:
    # We add this to set Java 17 for our pipeline environment
    - task: JavaToolInstaller@0
      inputs:
        versionSpec: '17'
        jdkArchitectureOption: 'x64'
        jdkSourceOption: 'PreInstalled'
        
    # We add this Gradle task to build with Gradle
    - task: Gradle@3
      inputs:
        gradleWrapperFile: 'gradlew'
        tasks: 'build'
        javaHomeOption: 'JDKVersion'

    - task: CopyFiles@2
      displayName: 'Copy Files to artifact staging directory'
      inputs:
        SourceFolder: '$(System.DefaultWorkingDirectory)'
        Contents: '**/build/libs/your_war.war'
        TargetFolder: $(Build.ArtifactStagingDirectory)

    - upload: $(Build.ArtifactStagingDirectory)
      artifact: drop

- stage: Deploy
  displayName: Deploy stage
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: DeployWindowsWebApp
    displayName: Deploy Windows Web App
    environment: $(environmentName)
    pool:
      vmImage: $(vmImageName)
    strategy:
      runOnce:
        deploy:
          steps:
          - task: AzureWebApp@1
            displayName: 'Azure Web App Deploy: yourapp'
            inputs:
              azureSubscription: $(azureSubscription)
              appType: webApp
              appName: $(webAppName)
              package: '$(Pipeline.Workspace)/drop/**/build/libs/your_war.war'
              # IMPORTANT: If you don't add this it will deploy to a context named after your WAR
              # ex. yoursite.azurewebsites.net/azure-0.0.1-SNAPSHOT/
              customDeployFolder: 'ROOT'

Azure DevOps - Why am I getting a 404 after deployment?

The same applies to what was covered in the Maven section above.

Troubleshooting

App works on Embedded Server, but not on Tomcat Web Server in Azure

It is worth checking if it works fine in a local machine using the following steps.

Download Apache Tomcat from https://tomcat.apache.org/download-10.cgi . Here I am using 10.1.31, but other versions are available in the same place.
I downloaded and installed “32-bit/64-bit Windows Service Installer”
If there is any conflict with the port while running the Tomcat, edit /conf/server.xml and change the port at the following place in server.xml

<Connector port="9000" protocol="HTTP/1.1"
  connectionTimeout="20000"
  redirectPort="8443"
  maxParameterCount="1000"
/>

NOTE: I changed to 9000 as my other app runs at 8080, if you don’t have any other apps running at 8080 / tomcat default port, you don’t need to make any changes.

Browse http://localhost:9000/manager/html
If this prompots with Username and Password, grab tomcat user credentials from /conf/tomcat-users.xml. It will be in the <tomcat-users></tomcat-users> section.
If you don’t find such thing, add the following line before </tomcat-users>

<user username="tomcat" password="xxyyzz" roles="manager-gui"/>

Copy the generated war file in the /webapps folder. After sometime, the war file gets extracted and deployed in the Tomcat (as shown below), which you can access from the /manager.html in the browser.

When you access the extracted war folder, the app will load its content.

If you see the same error as you saw in the Azure, fix it in the local machine and try deploying again.

NOTE: Sometimes, your app works in the IDE, but not in Web Server such as tomcat, that means there must be some configuration / code missing in the main class.

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Deploying WAR based Java applications with CI/CD (Azure DevOps) on App Service Windows

Overview

Local Development

Configuring for Maven

Configuring for Gradle

DevOps

Maven

Azure DevOps - Why am I getting a 404 after deployment?

Gradle

Azure DevOps - Why am I getting a 404 after deployment?

Troubleshooting

App works on Embedded Server, but not on Tomcat Web Server in Azure

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