<ul class="nav navbar-nav navbar-right">
    <li class="dropdown">
        <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false"><b> Iniciar sesión</b> <span class="caret"></span></a>
        <ul class="dropdown-menu dropdown-lr">
            <div class="col-lg-12">
                <form>
                    
                    <div class="form-group">
                        <label for=""><span class="glyphicon glyphicon-user" aria-hidden="true"></span> Nombre de usuario:</label>
                        <input class="form-control" type="text" name="user" value="" placeholder="user" required>
                    </div>
                    <div class="form-group">
                        <label for=""><span class="glyphicon glyphicon-lock" aria-hidden="true"></span> Contraseña:</label>
                        <input class="form-control" type="text" name="password" value="" placeholder="password" required>
                    </div>
                    <button type="button" (click)="signIn(user.value, password.value);" class="btn btn-success btn-block">Iniciar sesión</button>
                </form>
            </div>   
        </ul>
    </li>
</ul>