drivers/google/compute_util.go
func (c *ComputeUtil) addFirewallTag(instance *raw.Instance) error {
	log.Infof("Adding tag for the firewall rule")

	tags := instance.Tags
	for _, tag := range tags.Items {
		if tag == firewallTargetTag {
			return nil
		}
	}

	tags.Items = append(tags.Items, firewallTargetTag)

	op, err := c.service.Instances.SetTags(c.project, c.zone, instance.Name, tags).Do()
	if err != nil {
		return err
	}

	return c.waitForRegionalOp(op.Name)
}
func (c *ComputeUtil) addFirewallTag(instance *raw.Instance) error {
	log.Infof("Adding tag for the firewall rule")

	tags := instance.Tags
	for _, tag := range tags.Items {
		if tag == firewallTargetTag {
			return nil
		}
	}

	tags.Items = append(tags.Items, firewallTargetTag)

	op, err := c.service.Instances.SetTags(c.project, c.zone, instance.Name, tags).Do()
	if err != nil {
		return err
	}

	return c.waitForRegionalOp(op.Name)
}
// addFirewallTag adds a tag to the instance to match the firewall rule.