PHP tmp upload directory for multlple domains

I am hosting multiple domains on my Apache Web Server on Ubuntu 18.04 but I cannot set the tmp upload directory for PHP.

I tried putting this in my .htaccess for one of the domains, however nothing was stored when I tested.

php_value upload_tmp_dir /var/www/example.com/tmp/

My permissions for the /var/www/example.com/tmp/ folder are set at Chmod 775

Is there a working way to set this in .htaccess or in the domain's .conf file?

Solution

I've made something like that for my vhosts on my local machine. Note that everything is defined in my vhost because you can't change upload_tmp_dir and sys_temp_dir in runtime.

<VirtualHost *:80>
    ServerName example.local
    ServerAlias www.example.local
    
    UseCanonicalName On
    
    <Directory /mnt/storage/Server/example>
        DirectoryIndex index.php
        #Options +Indexes +FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>
    
    php_admin_value upload_tmp_dir /mnt/storage/Server/example/temp/
    php_admin_value sys_temp_dir /mnt/storage/Server/example/temp/
    
    DocumentRoot "/mnt/storage/Server/example"
    
    ErrorLog ${APACHE_LOG_DIR}/example.error.log
    CustomLog ${APACHE_LOG_DIR}/example.access.log combined
</VirtualHost>

How to confirm that everything works:

Create simple file:

$dir = sys_get_temp_dir();
$file = tempnam($dir, rand());
var_dump(get_current_user());
var_dump($dir);
var_dump('is_writable: ' . (int)is_writable($dir));
var_dump('is_readable: ' . (int)is_readable($dir));
var_dump($file);

Upload script: create file named upload.php

<?php
if (isset($_POST['submit'])) {
    var_dump($_FILES);
}
?>
<!DOCTYPE html>
<html>
    <body>
    <form action="upload.php" method="post" enctype="multipart/form-data">
        Select image to upload:
        <input type="file" name="upload" id="upload">
        <input type="submit" value="Upload Image" name="submit">
    </form>
    </body>
</html>