You can take an existing Quarkus HTTP application and deploy it as a native executable (Graal build) to Azure Functions using the Custom Handler runtime provided with Azure Functions.

Prerequisites:

You’ll need to configure a root path in application.properties:

quarkus.http.root-path=/api/{functionName}

Replace {functionName} with whatever you want to call the function you’re creating for the Quarkus HTTP application.

Next, rebuild your application to create a native executable targeting linux 64bit x86 runtime. 

$ mvn package -Pnative -DskipTests=true \
         -Dquarkus.native.container-build=true \
         -Dquarkus.native.builder-image=quay.io/quarkus/ubi-quarkus-mandrel-builder-image:jdk-17

After you do this create a directory in the root of your project and create function deployment descriptors. Specify anything you want for the name of the function

$ mkdir my-app
$ cd my-app
$ func new --language Custom --template HttpTrigger  \
                   --name my-func --authlevel anonymous

The func command will generate a custom handler host.json file and an http trigger function.json for you for the function named my-func.

Next copy your application’s native executable to your app directory:

$ cp ../target/code-with-quarkus-1.0.0-SNAPSHOT-runner app

Next you’ll need to edit my-func/function.json. Add a route that matches to all paths.

{
  "bindings": [
    {
      "authLevel": "Anonymous",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req",
      "methods": [
        "get",
        "post"
      ],
      "route": "{*path}"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    }
  ]
}

Without specifying a route, you will not be able to get requests to rest endpoints defined in your application.

Next you need to edit your host.json file to specify some configuration. You’ll need to enable http forwarding (enableForwardingHttpRequest), specify the executable name of your application (defaultExecutablePath), and define the http port for Quarkus to bind to by specifying a system property to pass to the application as an argument (arguments. Here’s what it should look like in the end:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[3.*, 4.0.0)"
  },
  "customHandler": {
    "enableForwardingHttpRequest": true,
    "description": {
    "defaultExecutablePath": "app",
    "workingDirectory": "",
	"arguments": [
       "-Dquarkus.http.port=${FUNCTIONS_CUSTOMHANDLER_PORT:8080}"
      ]
    }
  }
}

Test Locally

To test locally, use the func start command. Make sure you are in the my-app directory you created earlier!

$ func start


# Azure Functions Core Tools
# Core Tools Version:       4.0.5198 Commit hash: N/A  (64-bit)
#Function Runtime Version: 4.21.1.20667
#
#
# Functions:
#
#	my-func: [GET,POST] http://localhost:7071/api/my-func/{*path}
#
# For detailed output, run func with --verbose flag.
# [2023-08-10T19:08:59.190Z] __  ____  __  _____   ___  __ ____  ______ 
# [2023-08-10T19:08:59.191Z]  --/ __ \/ / / / _ | / _ \/ //_/ / / / __/ 
# [2023-08-10T19:08:59.191Z]  -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\ \   
# [2023-08-10T19:08:59.191Z] --\___\_\____/_/ |_/_/|_/_/|_|\____/___/   
# [2023-08-10T19:08:59.191Z] 2023-08-10 15:08:59,187 INFO  [io.quarkus] (main) code-with-quarkus-1.0.0-SNAPSHOT native (powered by Quarkus 999-SNAPSHOT) started in 0.043s. Listening on: http://0.0.0.0:33917
# [2023-08-10T19:08:59.191Z] 2023-08-10 15:08:59,188 INFO  [io.quarkus] (main) Profile prod activated. 
# [2023-08-10T19:08:59.191Z] 2023-08-10 15:08:59,188 INFO  [io.quarkus] (main) Installed features: [cdi, resteasy, smallrye-context-propagation, vertx]
# [2023-08-10T19:08:59.209Z] Worker process started and initialized.
# [2023-08-10T19:09:04.023Z] Host lock lease acquired by instance ID '000000000000000000000000747C0C10'.

To test go to http://localhost:7071/api/my-func/hello. The hello part of the path can be replaced with your REST API.

Deployment

To deploy you’ll need to create an Azure Group and Function Application. 

# login
$ az login

# list subscriptions
$ az account list -o table

# set active subscription.  You do not have to do this if you only have one subscription
$ az account set --subscription <SUBSCRIPTION_ID>

# create an Azure Resource Group 
az group create -n rg-quarkus-functions \
  -l eastus

# create an Azure Storage Account (required for Azure Functions App)
az storage account create -n sargquarkusfunctions2023 \
  -g rg-quarkus-functions \
  -l eastus

# create an Azure Functions App
az functionapp create -n my-app-quarkus \
  -g rg-quarkus-functions \
  --consumption-plan-location eastus\
  --os-type Linux \
  --runtime custom \
  --functions-version 4 \
  --storage-account sargquarkusfunctions2023

Make sure that the os-type is Linux!!! Note that your Function Application name must be unique and may collide with others.

Now you can deploy your application. Again, make sure you are in the my-app directory!

$ func azure functionapp publish my-app-quarkus

# Getting site publishing info...
# Uploading package...
# Uploading 15.32 MB 
# Upload completed successfully.
# Deployment completed successfully.
# Syncing triggers...
# Functions in my-app-quarkus:
#    my-func - [httpTrigger]
#         Invoke url: https://my-app-quarkus.azurewebsites.net/api/{*path}

A successful deployment will tell you how to access the app. Just remember the root context will always be /api/{functionName}.