use relative path for login action

                    </div>

                </div>

                <div>

                    <form class="form-signin" action="/auth/login" method="POST">

                    <form class="form-signin" action="auth/login" method="POST">

                        <div class="form-group">

                            <label for="inputUser" class="sr-only">User</label>

                            <input type="text" name="user" id="inputUser" class="form-control form-control-sm" placeholder="LDAP user" required autofocus>