Auto redirect to login page if the user isn't logged in

/**
 * Auto redirect to login page if the user isn't logged in
 */
add_action( 'wp', function(){
    // Define member page ID
    $members_page_id = 103;

    if( is_page( $members_page_id ) && ! is_user_logged_in() ){
        wp_redirect( wp_login_url( get_permalink( $members_page_id ) ) );
        exit;
    }
} );