Tutorial: Deploy to Azure App Service with Jenkins and the Azure CLI

Article
05/30/2023

Important

Many Azure services have Jenkins plug-ins. Some of these plug-ins will be out of support as of February 29, 2024. Azure CLI is the currently recommended way to integrate Jenkins with Azure services. For more information, refer to the article Jenkins plug-ins for Azure.

To deploy a Java web app to Azure, you can use Azure CLI in a Jenkins Pipeline. In this tutorial, you do the following tasks:

Create a Jenkins VM
Configure Jenkins
Create a web app in Azure
Prepare a GitHub repository
Create Jenkins pipeline
Run the pipeline and verify the web app

Prerequisites

Azure subscription: If you don't have an Azure subscription, create a free account before you begin.

Jenkins - Install Jenkins on a Linux VM
Azure CLI: Install Azure CLI (version 2.0.67 or higher) on the Jenkins server.

Configure Jenkins

The following steps show how to install the required Java JDK and Maven on the Jenkins controller:

Download and install the Azul Zulu build of OpenJDK for Azure from an apt-get repository:

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 0xB1998361219BD9C9
sudo apt-add-repository "deb http://repos.azul.com/azure-only/zulu/apt stable main"
sudo apt-get -q update
sudo apt-get -y install zulu-8-azure-jdk

Run the following command to install Maven:
```
sudo apt-get install -y maven
```

Add Azure service principal to a Jenkins credential

The following steps show how to specify your Azure credential:

Make sure the Credentials plug-in is installed.
Within the Jenkins dashboard, select Credentials -> System ->.
Select Global credentials(unrestricted).
Select Add Credentials to add a Microsoft Azure service principal. Make sure that the credential kind is Username with password and enter the following items:
- Username: Service principal appId
- Password: Service principal password
- ID: Credential identifier (such as AzureServicePrincipal)

Create an Azure App Service for deploying the Java web app

Use az appservice plan create to create an Azure App Service plan with the FREE pricing tier:

az appservice plan create \
    --name <app_service_plan> \ 
    --resource-group <resource_group> \
    --sku FREE

Key points:

The appservice plan defines the physical resources used to host your apps.
All applications assigned to an appservice plan share these resources.
Appservice plans allow you to save cost when hosting multiple apps.

Create an Azure web app

Use az webapp create to create a web app definition in the myAppServicePlan App Service plan.

az webapp create \
    --name <app_name> \ 
    --resource-group <resource_group> \
    --plan <app_service_plan>

Key points:

The web app definition provides a URL to access your application with and configures several options to deploy your code to Azure.
Substitute the <app_name> placeholder with a unique app name.
The app name is part of the default domain name for the web app. Therefore, the name needs to be unique across all apps in Azure.
You can map a custom domain name entry to the web app before you expose it to your users.

Configure Java

Use az appservice web config update to set up the Java runtime configuration for the app:

az webapp config set \ 
    --name <app_name> \
    --resource-group <resource_group> \ 
    --java-version 1.8 \ 
    --java-container Tomcat \
    --java-container-version 8.0

Prepare a GitHub repository

Open the Simple Java Web App for Azure repo.
Select the Fork button to fork the repo to your own GitHub account.
Open the Jenkinsfile file by clicking on the file name.
Select the pencil icon to edit the file.

Update the subscription ID and tenant ID.

  withEnv(['AZURE_SUBSCRIPTION_ID=<subscription_id>',
        'AZURE_TENANT_ID=<tenant_id>'])

Update the resource group and name of your web app on line 22 and 23 respectively.
```
def resourceGroup = '<resource_group>'
def webAppName = '<app_name>'
```

Update the credential ID in your Jenkins instance

withCredentials([usernamePassword(credentialsId: '<service_principal>', passwordVariable: 'AZURE_CLIENT_SECRET', usernameVariable: 'AZURE_CLIENT_ID')]) {

Create Jenkins pipeline

Do the following to create a Jenkins pipeline:

Open Jenkins in a web browser.
Select New Item.
Enter a name for the job.
Select Pipeline.
Select OK.
Select Pipeline.
For Definition, select Pipeline script from SCM.
For SCM, select Git.
Enter the GitHub URL for your forked repo: https:\<forked_repo\>.git
Select Save

Test your pipeline

Go to the pipeline you created
Select Build Now
After the build completes, select Console Output to see build details.

Verify your web app

Do the following to verify the WAR file is deployed successfully to your web app:

Browse to the following URL: http://<app_name>.azurewebsites.net/api/calculator/ping

You should see text similar to the following:

Welcome to Java Web App!!! This is updated!
Today's date

Browse to the following URL (substitute <x> and <y> with two values to be summed): http://<app_name>.azurewebsites.net/api/calculator/add?x=<x>&y=<y>.

Deploy to Azure App Service on Linux

App Service can also host web apps natively on Linux for supported application stacks. It can also run custom Linux containers (also known as Web App for Containers.)

You can modify the script to deploy to an Azure App Service on Linux. App Service on Linux supports Docker. As such, you provide a Dockerfile that packages your web app with service runtime into a Docker image. The plug-in builds the image, pushes it to a Docker registry, and deploys the image to your web app.

Refer to Migrate custom software to Azure App Service using a custom container to create an Azure App Service on Linux and an Azure Container Registry.

    az group create --name myResourceGroup2 --location westus2
    az acr create --name myACRName --resource-group myResourceGroup2 --sku Basic --admin-enabled true
    az appservice plan create --name myAppServicePlan --resource-group  myResourceGroup2 --is-linux
    az webapp create --resource-group myResourceGroup2 --plan myAppServicePlan --name myApp --deployment-container-image-name myACRName.azurecr.io/calculator:latest

Install Docker on your Jenkins.
Make sure Docker Pipeline plug-in is installed.

In the same Simple Java Web App for Azure repo you forked, edit the Jenkinsfile2 file as follows: