<div class="btn-group">
    <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    This dropdown's menu is right-aligned
    </button>
    <div class="dropdown-menu dropdown-menu-right">
       <button class="dropdown-item" type="button">Action</button>
       <button class="dropdown-item" type="button">Another action</button>
       <button class="dropdown-item" type="button">Something else here</button>
    </div>
</div>