Running PHP in Azure Functions

Hi friends! Happy April Fools’ Day! Recently, Microsoft added a new feature to Azure Functions called Custom Handlers. It basically allows you to write Azure Function in any language (kind of reminds me of how Dapr handles communication) and benefit from all the input and output bindings as well. In this article, I will demonstrate how to set it up with PHP.

As per the picture, you can see that the Functions Host expects a web server to be running (defined in host.json) and passes the the request payload.

The setup is going to be fairly simple. In order to run PHP web server, we will use the built-in one in PHP. You can start this server locally by just calling php -S localhost:3000 in the directory where your code is, it will serve the requests. With Custom Handlers, the port however is passed via an environment variable FUNCTIONS_HTTPWORKER_PORT. The issue is, that the PHP server needs the port at startup, so what we need to do is to execute this via either Batch or bash script which will pull the correct port and start the PHP server.

I created a Function app on Windows dedicated App Service Plan. There, I modified the host.json to execute the desired script:

{
  "version": "2.0",
  "httpWorker": {
    "description": {
      "defaultExecutablePath": "phpServer.bat"
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[1.*, 2.0.0)"
  }
}

Then the phpServer.bat which we need to place into the wwwroot directory:

php -S 127.0.0.1:%FUNCTIONS_HTTPWORKER_PORT% functionRouter.php

Note that 127.0.0.1 is used instead of localhost. This is due to PHP’s server binding to specific hostname I suppose. The Functions runtime is calling it via 127.0.0.1 so we need to have it there.

Next step is to define the functions. I setup two functions - function1 and function2. function1 is a simple HTTP in-out function, while function2 is also outputting a message into Azure Storage Queue.

/function1/function.json:

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

/function2/function.json:

{
  "bindings": [
    {
      "type": "httpTrigger",
      "authLevel": "function",
      "direction": "in",
      "name": "req",
      "methods": ["post"]
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    },
    {
      "type": "queue",
      "name": "message",
      "direction": "out",
      "queueName": "orders",
      "connection": "AzureWebJobsStorage"
    }
  ]
}

The last piece is to write the PHP script to handle this the functionRouter.php. It is a very simple router, which checks which function to trigger and runs the code. Note that which function2 we output a JSON response, hence the Content-Type header and we also emit some logs and write to the queue. The logs then appear in Application Insights linked with the function.

<?php

if(strpos($_SERVER['REQUEST_URI'], "/function1") !== FALSE) {
    if($_SERVER["REQUEST_METHOD"] == "GET") {
        $name = "World";
        if(isset($_GET["name"])) {
            $name = $_GET["name"];
        }
        echo "Hello ".$name." from an Azure Function written in PHP!";
    }
    else if($_SERVER["REQUEST_METHOD"] == "POST") {
        $name = "World";
        $json = file_get_contents('php://input');
        $jsonBody = json_decode($json, true);
        if(isset($jsonBody["name"])) {
            $name = $jsonBody["name"];
        }
        echo "Hello ".$name." from an Azure Function written in PHP!";
    }
}
else if(strpos($_SERVER['REQUEST_URI'], "/function2") !== FALSE) {
    header("Content-Type: application/json");
    if($_SERVER["REQUEST_METHOD"] == "POST") {
        $name = "World";
        $json = file_get_contents('php://input');
        $jsonBody = json_decode($json, true);
        if(isset($jsonBody["name"])) {
            $name = $jsonBody["name"];
        }
        $message = "Hello ".$name." from an Azure Function written in PHP!";
        echo json_encode([
            "Outputs" => [
                "message" => $message,
                "res" => [
                    "statusCode" => 200,
                    "body" => $message
                ]
            ],
            "Logs" => [
                "Request completed"
            ]
        ]);
    }
}
else {
    phpinfo();
}

So as you can see, the Custom Handlers in Azure Functions can pretty much run any language, including your PHP code and you can easily integrate it with Azure Functions Bindings. Two more things to note:

• The default PHP version on the Windows worker is 5.6, which you probably want to change. If you want to make such a change, you can use either the az CLI or Resource Explorer - you need to navigate to <yoursitename>/config/web and change the phpVersion property to for example 7.3.
• I wouldn’t really use this in production, since the built-in PHP webserver is only for testing, and not really production workloads.