How to redirect anonymous user in Drupal 8 & 9

How to redirect anonymous user in Drupal 8 & 9

Create MODULENAME.info.yml file

name: Redirect Anonymous User
type: module
description: Redirect anonymous user to login page
package: Custom
core: 8.x

Create custom service like this:

services:
  redirect_anonymous_user.event_subscriber:
    class: Drupal\redirect_anonymous_user\EventSubscriber\RedirectAnonymousUser
    arguments: []
    tags:
      - {name: event_subscriber}

Create class RedirectAnonymousUser:

<?php

namespace Drupal\redirect_anonymous_user\EventSubscriber;

use Symfony\Component\HttpFoundation\RedirectResponse;
use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Drupal\Core\Url;


/**
 * Event subscriber subscribing to KernelEvents::REQUEST.
 */
class RedirectAnonymousUser implements EventSubscriberInterface
{

    public function __construct() {
        $this->account = \Drupal::currentUser();
    }

    public function checkAuthStatus(GetResponseEvent $event) {

        if ($this->account->isAnonymous() && \Drupal::service('path.current')->getPath() == '/node/add/article') {

            // add logic to check other routes you want available to anonymous users,
            // otherwise, redirect to login page.
            $route_name = \Drupal::routeMatch()->getRouteName();
            if (strpos($route_name, 'view') === 0 && strpos($route_name, 'rest_') !== FALSE) {
                return;
            }

            $response = new RedirectResponse('/user/login?destination=/node/add/article', 301);
            $event->setResponse($response);
            $event->stopPropagation();
        }
    }

    public static function getSubscribedEvents() {
        $events[KernelEvents::REQUEST][] = array('checkAuthStatus');
        return $events;
    }
}