Create your first function with Java and Maven (Preview)

Note

Java for Azure Functions is currently in preview.

This quickstart guides through creating a serverless function project with Maven, testing it locally, and deploying it to Azure. When you're done, your Java function code is running in the cloud and can be triggered from an HTTP request.

Access a Hello World function from the command line with cURL

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

Prerequisites

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

Important

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

Install the Azure Functions Core Tools

The Azure Functions Core Tools 2.0 provide a local development environment for writing, running, and debugging Azure Functions.

To install, visit the Installing section of the Azure Functions Core Tools project to find the specific instructions for your operating system.

You can also install it manually with npm, included with Node.js, after installing the following requirements:

To proceed with an npm-based installation, run:

npm install -g azure-functions-core-tools@core

Note

If you have trouble installing Azure Functions Core Tools version 2.0, see Version 2.x runtime.

Generate a new Functions project

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

Linux/MacOS

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

Windows (CMD)

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

Maven will ask you for values needed to finish generating the project. For groupId, artifactId, and version values, see the Maven naming conventions reference. The appName value must be unique across Azure, so Maven generates an app name based on the previously entered artifactId as a default. The packageName value determines the Java package for the generated function code.

The com.fabrikam.functions and fabrikam-functions identifiers below are used as an example and to make later steps in this quickstart easier to read. You are encouraged to supply your own values to Maven in this step.

Define value for property 'groupId': com.fabrikam.functions
Define value for property 'artifactId' : fabrikam-functions
Define value for property 'version' 1.0-SNAPSHOT : 
Define value for property 'package': com.fabrikam.functions
Define value for property 'appName' fabrikam-functions-20170927220323382:
Confirm properties configuration: Y

Maven creates the project files in a new folder with a name of artifactId, in this example fabrikam-functions. The ready to run generated code in the project is a simple HTTP triggered function that echoes the body of the request:

public class Function {
    /**
     * This function listens at endpoint "/api/hello". Two ways to invoke it using "curl" command in bash:
     * 1. curl -d "HTTP Body" {your host}/api/hello
     * 2. curl {your host}/api/hello?name=HTTP%20Query
     */
    @FunctionName("hello")
    public HttpResponseMessage<String> hello(
            @HttpTrigger(name = "req", methods = {"get", "post"}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
            final ExecutionContext context) {
        context.getLogger().info("Java HTTP trigger processed a request.");

        // Parse query parameter
        String query = request.getQueryParameters().get("name");
        String name = request.getBody().orElse(query);

        if (name == null) {
            return request.createResponse(400, "Please pass a name on the query string or in the request body");
        } else {
            return request.createResponse(200, "Hello, " + name);
        }
    }
}

Run the function locally

Change directory to the newly created project folder and build and run the function with Maven:

cd fabrikam-function
mvn clean package 
mvn azure-functions:run

Note

If you're experiencing this exception: javax.xml.bind.JAXBException with Java 9, see the workaround on GitHub.

You see this output when the function is running locally on your system and ready to respond to HTTP requests:

Listening on http://localhost:7071
Hit CTRL-C to exit...

Http Functions:

   hello: http://localhost:7071/api/hello

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

curl -w '\n' -d LocalFunction http://localhost:7071/api/hello
Hello LocalFunction!

Use Ctrl-C in the terminal to stop the function code.

Deploy the function to Azure

The deploy process to Azure Functions uses account credentials from the Azure CLI. Log in with the Azure CLI before continuing.

az login

Deploy your code into a new Function app using the azure-functions:deploy Maven target.

mvn azure-functions:deploy

When the deploy is complete, you see the URL you can use to access your Azure function app:

[INFO] Successfully deployed Function App with package.
[INFO] Deleting deployment package from Azure Storage...
[INFO] Successfully deleted deployment package fabrikam-function-20170920120101928.20170920143621915.zip
[INFO] Successfully deployed Function App at https://fabrikam-function-20170920120101928.azurewebsites.net
[INFO] ------------------------------------------------------------------------

Test the function app running on Azure using cURL. You'll need to change the URL from the sample below to match the deployed URL for your own function app from the previous step.

curl -w '\n' https://fabrikam-function-20170920120101928.azurewebsites.net/api/hello -d AzureFunctions
Hello AzureFunctions!

Make changes and redeploy

Edit the src/main.../Function.java source file in the generated project to alter the text returned by your Function app. Change this line:

return request.createResponse(200, "Hello, " + name);

To the following:

return request.createResponse(200, "Hi, " + name);

Save the changes and redeploy by running azure-functions:deploy from the terminal as before. The function app will be updated and this request:

curl -w '\n' -d AzureFunctionsTest https://fabrikam-functions-20170920120101928.azurewebsites.net/api/HttpTrigger-Java

Will have updated output:

Hi, AzureFunctionsTest

Next steps

You have created a Java function app with a simple HTTP trigger and deployed it to Azure Functions.