<divclass="input-group mb-3"><inputtype="text"class="form-control"placeholder="Recipient's username"aria-label="Recipient's username"aria-describedby="basic-addon2"><divclass="input-group-append"><buttonclass="btn btn-outline-secondary"type="button">Button</button></div>
</div>
https://getbootstrap.com/docs/4.0/components/input-group/