Increasing file upload size on App Service Linux PHP

This post will cover how to increase the default file upload size on App Service Linux PHP images

Overview

Before starting, this is specifically for PHP 8.x “Blessed images” on App Service Linux - eg: Create a PHP web app in Azure App Service. These use NGINX and php-fpm to serve PHP scripts.

If you’re looking to use/host Wordpress - consider using the Docker Image on App Service that’s offered specifically for Wordpress - you can get started by following App Service Linux - Create a WordPress site. This Wordpress image already has file upload size increased to a reasonable amount.

The “PHP Blessed image” described earlier above is more-so for running typical PHP applications or frameworks like Laravel, Yii, or others.

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When doing file uploads, there’s a couple of things to know and consider:

Default upload sizes - the default file uploads on the PHP App Service Linux images are set to the following:

• NGINX: Since NGINX is used, this has it’s own consideration of client_max_body_size, which is not set in any NGINX config in these images. Therefor, the default is 1MB
• PHP: upload_max_filesize is set to 2MB
• Application: Your application may have its own file size validation, like seen below

You can check PHP “core” defaults by adding a <?php phpinfo(); ?> to a phpinfo.php file under /home/site/wwwroot or call this via the PHP CLI.

NOTE: If file uploads are slow, you may want to consider increasing max_execution_time through a custom .ini file. The default for this is 30 seconds.

The typical behavior seen when not increasing this is that file sizes over 1MB will return a HTTP 413 from NGINX. For example, if we use try to upload a 2.2MB file, as seen below:

We’ll end up encountering the below HTTP 413 from NGINX:

For this to succeed - you need to increase both NGINX’s and PHP’s file size upload limits.

Configuration

We’ll use a real world example with Laravel.

(routes/web.php)

Route::get('/', function () {
    return view('upload');
});

Route::post('/api/upload', [UploadController::class, 'uploadFile'])->name('uploadFile');

(app/Http/Controllers/UploadController.php)

class UploadController extends Controller
{
    public function uploadFile(Request $request)
    {
        // Max file size: 10MB
        $request->validate([
            'file' => 'required|file|max:10240',
        ]);
        // Store file in storage/app/uploads directory
        $file = $request->file('file');
        $fileName = time() . '_' . $file->getClientOriginalName();
        $file->storeAs('uploads', $fileName); 

        return redirect()->back()->with('message', 'File uploaded successfully.');
    }
}

(resources/views/upload.blade.php)

<form action="/api/upload" method="post" enctype="multipart/form-data">
    @csrf
    <input type="file" name="file">
    <button type="submit">Upload</button>
</form>
@if (session('message'))
    <div class="mt-5">
        <p class="text-green-400"></p>
    </div>
@endif

Increase NGINX’s file size:

1. You can generally follow NGINX Rewrite Rules for Azure App Service Linux PHP 8.x on how to override NGINX’s default file under /etc/nginx/sites-avaialable/default or follow the below.
   • a) Go into an SSH session within the application container and run cp /etc/nginx/sites-available/default /home/default

   • b) Update the default file to include client_max_body_size in the server block as seen below. Set this to a sensible value:

       server {
           #proxy_cache cache;
               #proxy_cache_valid 200 1s;
           listen 8080;
           listen [::]:8080;
           # This was changed from /home/site/wwwroot to /home/site/wwwroot/public for Laravel
           root /home/site/wwwroot/public;
           index  index.php index.html index.htm;
           server_name  example.com www.example.com; 
           port_in_redirect off;
           # IMPORTANT: Add this in. 10M is 10MB. Change as needed
           client_max_body_size 10M;   
     
           ... rest of other nginx content
       }   
     

   • c) Either create a startup.sh file under /home (or elsewhere) or use the in-line version for your custom Startup Command

     If using startup.sh, add the following:

       #!/bin/sh
     
       echo "Copying default to /etc/nginx/sites-available/default"
       cp /home/default /etc/nginx/sites-available/default
     
       echo "Reloading NGINX.."
       service nginx reload
     

     Then, in the Azure Portal -> Configuration for your PHP application, add the location of your startup.sh file:

     

     Or, if opting to use an in-line command, just add cp /home/default /etc/nginx/sites-available/default && service nginx reload

     

   • d) Click “Save” at the top when finished

Increase PHP’s default upload size:

1. You can follow Configure a PHP app for Azure App Service - Customize php.ini settings or follow the below
   • a) In an SSH session within the application container, create an ini folder. We’ll create one with mkdir /home/site/ini
   • b) Create an custom .ini file to increase the upload size with echo "upload_max_filesize=50M" >> /home/site/ini/extensions.ini
   • c) Then, in the Azure Portal -> Configuration for your PHP application, add the environment variable PHP_INI_SCAN_DIR to load this custom .ini in. Set this to the value of /home/site/ini/:

   

   • d) Click “Save” at the top when finished

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At this point, after increasing both PHP’s and NGINX’s max allowed file size values - you should now be able to upload files greater than 1MB for NGINX and 2MB for PHP.

Summary

You need to increase NGINX’s client_max_body_size (which has a default of 1MB) and PHP’s upload_max_filesize (which h as a default of 2MB) - otherwise, you may encounter an HTTP 413, or, an error returned from PHP - when uploading files greater than 1MB for NGINX and 2MB for PHP.