og.routing.yml

# Routes for Organic groups.

og.subscribe:
  path: 'group/{entity_type_id}/{group}/subscribe/{membership_type}'
  defaults:
    _controller: '\Drupal\og\Controller\SubscriptionController::subscribe'
    _title: 'Join Group'
    membership_type: default
  requirements:
    # Only authenticated users can subscribe to group, but we do allow anonymous
    # users to reach this route. They will be redirect to login page or be given
    # the correct page by the controller.
    _access: 'TRUE'
  options:
    parameters:
      group:
        type: entity:{entity_type_id}
      membership_type:
        type: entity:og_membership_type

og.unsubscribe:
  path: 'group/{entity_type_id}/{group}/unsubscribe'
  defaults:
    _controller: '\Drupal\og\Controller\SubscriptionController::unsubscribe'
    _title: 'Leave Group'
  requirements:
    _user_is_logged_in: 'TRUE'
  options:
    parameters:
      group:
        type: entity:{entity_type_id}