code: func UpdateConfigHandler(ctx *router.Context) {
  	c, h := ctx.Context, ctx.Writer
  	// Needed to access the PubSub API
  	c = appengine.WithContext(c, ctx.Request)
  	projErr := common.UpdateConsoles(c)
  	if projErr != nil {
  		if merr, ok := projErr.(errors.MultiError); ok {
  			for _, ierr := range merr {
  				logging.WithError(ierr).Errorf(c, "project update handler encountered error")
  			}
  		} else {
  			logging.WithError(projErr).Errorf(c, "project update handler encountered error")
  		}
  	}
  	settings, servErr := common.UpdateServiceConfig(c)
  	if servErr != nil {
  		logging.WithError(servErr).Errorf(c, "service update handler encountered error")
  	} else {
  		servErr = common.EnsurePubSubSubscribed(c, settings)
  		if servErr != nil {
  			logging.WithError(servErr).Errorf(
  				c, "pubsub subscriber handler encountered error")
  		}
  	}
  	if projErr != nil || servErr != nil {
  		h.WriteHeader(http.StatusInternalServerError)
  		return
  	}
  	h.WriteHeader(http.StatusOK)
  }
docs: // UpdateHandler is an HTTP handler that handles configuration update requests.