Quickstart: Use Java and Maven/Gradle to create and publish a function to Azure

This article shows you how to build and publish a Java function to Azure Functions with the Maven/Gradle command-line tool. When you're done, your function code runs in Azure in a serverless hosting plan and is triggered by an HTTP request.

Prerequisites

To develop functions using Java, you must have the following installed:

  • Gradle, version 4.10 and above

You also need an active Azure subscription. If you don't have an Azure subscription, create a free account before you begin.

Important

The JAVA_HOME environment variable must be set to the install location of the JDK to complete this quickstart.

Prepare a Functions project

In an empty folder, run the following command to generate the Functions project from a Maven archetype.

mvn archetype:generate -DarchetypeGroupId=com.microsoft.azure -DarchetypeArtifactId=azure-functions-archetype 

Note

If you're using Powershell, remeber to add "" around parameters.

Note

If you're experiencing issues with running the command, take a look at what maven-archetype-plugin version is used. Because you are running the command in an empty directory with no .pom file, it might be attempting to use a plugin of the older version from ~/.m2/repository/org/apache/maven/plugins/maven-archetype-plugin if you upgraded your Maven from an older version. If so, try deleting the maven-archetype-plugin directory and re-running the command.

Maven asks you for values needed to finish generating the project on deployment. Provide the following values when prompted:

Value Description
groupId A value that uniquely identifies your project across all projects, following the package naming rules for Java. The examples in this quickstart use com.fabrikam.functions.
artifactId A value that is the name of the jar, without a version number. The examples in this quickstart use fabrikam-functions.
version Choose the default value of 1.0-SNAPSHOT.
package A value that is the Java package for the generated function code. Use the default. The examples in this quickstart use com.fabrikam.functions.

Type Y or press Enter to confirm.

Maven creates the project files in a new folder with a name of artifactId, which in this example is fabrikam-functions. Run the following command to change the directory to the created project folder.

cd fabrikam-function

Use the following command to clone the sample project:

git clone https://github.com/Azure-Samples/azure-functions-samples-java.git
cd azure-functions-samples-java/

Open build.gradle and change the appName in the following section to a unique name to avoid domain name conflict when deploying to Azure.

azurefunctions {
    resourceGroup = 'java-functions-group'
    appName = 'azure-functions-sample-demo'
    pricingTier = 'Consumption'
    region = 'westus'
    runtime {
      os = 'windows'
    }
    localDebug = "transport=dt_socket,server=y,suspend=n,address=5005"
}

Open the new Function.java file from the src/main/java path in a text editor and review the generated code. This code is an HTTP triggered function that echoes the body of the request.

Run the function locally

Run the following command to build then run the function project:

mvn clean package 
mvn azure-functions:run
gradle jar --info
gradle azureFunctionsRun

You will see output like the following from Azure Functions Core Tools when you run the project locally:

...

Now listening on: http://0.0.0.0:7071
Application started. Press Ctrl+C to shut down.

Http Functions:

    HttpExample: [GET,POST] http://localhost:7071/api/HttpExample
...

Trigger the function from the command line using cURL in a new terminal window:

curl -w "\n" http://localhost:7071/api/HttpExample --data AzureFunctions
Hello AzureFunctions!

The function key isn't required when running locally. Use Ctrl+C in the terminal to stop the function code.

Deploy the function to Azure

A function app and related resources are created in Azure when you first deploy your function app. Before you can deploy, use the az login Azure CLI command to sign in to your Azure subscription.

az login

Tip

If your account can access multiple subscriptions, use az account set to set the default subscription for this session.

Use the following command to deploy your project to a new function app.

mvn azure-functions:deploy
gradle azureFunctionsDeploy

This will create the following resources in Azure:

  • Resource group. Named with the resourceGroup you supplied.
  • Storage account. Required by Functions. The name is generated randomly based on Storage account name requirements.
  • App service plan. Serverless hosting for your function app in the specified appRegion. The name is generated randomly.
  • Function app. A function app is the deployment and execution unit for your functions. The name is your appName, appended with a randomly generated number.

The deployment also packages the project files and deploys them to the new function app using zip deployment, with run-from-package mode enabled.

After the deployment completes, you see the URL you can use to access your function app endpoints. Because the HTTP trigger we published uses authLevel = AuthorizationLevel.FUNCTION, you need to get the function key to call the function endpoint over HTTP. The easiest way to get the function key is from the Azure portal.

Get the HTTP trigger URL

You can get the URL required to trigger your function, with the function key, from the Azure portal.

  1. Browse to the Azure portal, sign in, type the appName of your function app into Search at the top of the page, and press enter.

  2. In your function app, expand Functions (Read Only), choose your function, then select </> Get function URL at the top right.

    Copy the function URL from the Azure portal

  3. Choose default (Function key) and select Copy.

You can now use the copied URL to access your function.

Verify the function in Azure

To verify the function app running on Azure using cURL, replace the URL from the sample below with the URL that you copied from the portal.

curl -w "\n" https://fabrikam-functions-20190929094703749.azurewebsites.net/api/HttpExample?code=zYRohsTwBlZ68YF.... --data AzureFunctions

This sends a POST request to the function endpoint with AzureFunctions in the body of the request. You see the following response.

Hello AzureFunctions!

Next steps

You've created a Java functions project with an HTTP triggered function, run it on your local machine, and deployed it to Azure. Now, extend your function by...