Magento 2: Call custom admin controller from frontend

Question

Is there a way to call custom admin controller (which prints a pdf file from sales order view page) from frontend download anchor link?

<a href="http://m7.local/index.php/admin/magemechanic_workorder/order/print/order_id/<?php echo $orderId ?>" download>Download</a>

Answer 1

As per the updated question, no, you cannot configure Magento to invoke an adminhtml controller from the frontend for security reasons. Put the code in a class, and invoke that class from both the adminthml and frontend controllers separately.

Original answer to the original question regarding invoking one controller from another:

You can invoke a controller just like any other code. Use Dependency Injection to get an instance on your constructor, then invoke a method on that object.

<?php
namespace Vendor\Mod\Foo\Bar;

use Vendor\Mod\Controller\Adminhtml\Custom;

class Foobar {

    /** @var Custom */
    protected $_custom;

    public function __construct(Custom $custom)
    {
        $this->_custom = $custom;
    }


    public function foo()
    {
        $this->_custom->initPage();
    }

}