xxxxxxxxxx
<div class="input-group col-md-4">
<input class="form-control py-2 border-right-0 border" type="search" value="search" id="example-search-input">
<span class="input-group-append">
<button class="btn btn-outline-secondary border-left-0 border" type="button">
<i class="fa fa-search"></i>
</button>
</span>
</div>
xxxxxxxxxx
<div class="input-group">
<div class="input-group-prepend">
<span class="input-group-text">
<i class="fa fa-search" aria-hidden="true"></i>
</span>
</div>
<input type="text" class="form-control" placeholder="Search">
</div>