We can do like below.

Widget

from django import forms
from django.template import loader
from django.utils.safestring import mark_safe


class MyWidget(forms.Widget):
    template_name = 'widget_template.html'

    def get_context(self, name, value, attrs=None):
        return {'widget': {
            'name': name,
            'value': value,
        }}

    def render(self, name, value, attrs=None):
        context = self.get_context(name, value, attrs)
        template = loader.get_template(self.template_name).render(context)
        return mark_safe(template)

widget_template.html

<div class="form-group input-group">
    <span class="input-group-addon">Name</span>
        <input type="text" class="form-control" id="mywidget-{{ widget.name }}" name="{{ widget.name }}" />
</div>