'iterates each service tag and adds the node to groups derived from the
service and tag names e.g. nginx_master'

def extract_groups_from_tags(self, service_name, service, node_data):

    if (self.config.has_config('tags') and service['Tags']):
        tags = service['Tags']
        self.add_metadata(node_data, ('consul_%s_tags' % service_name), tags)
        for tag in service['Tags']:
            tagname = ((service_name + '_') + tag)
            self.add_node_to_map(self.nodes_by_tag, tagname, node_data['Node'])
