<code>CUSTOM</code> action in the authorization policy allows you to easily integrate Istio with any external
authorization system with the following benefits:</p><ul><li><p>First-class support in the authorization policy API</p></li><li><p>Ease of usage: define the external authorizer simply with a URL and enable with the authorization policy, no more
hassle with the <code>EnvoyFilter</code> API</p></li><li><p>Conditional triggering, allowing improved performance</p></li><li><p>Support for various deployme