<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<h5>Bootstrap 4 Search Bar</h5>
<div class="row">
<div class="col-12">
<div class="input-group">
<input class="form-control border-secondary py-2" type="search" value="search">
<div class="input-group-append">
<button class="btn btn-outline-secondary" type="button">
<i class="fa fa-search"></i>
</button>
</div>
</div>
</div>
</div>
</div>
