func changefeed(logger ctxu.Logger, store storage.MetaStore, imageName, changeID string, records int64) ([]byte, error) {
	changes, err := store.GetChanges(changeID, int(records), imageName)
	if err != nil {
		logger.Errorf("%d GET could not retrieve records: %s", http.StatusInternalServerError, err.Error())
		return nil, errors.ErrUnknown.WithDetail(err)
	}
	out, err := json.Marshal(&changefeedResponse{
		NumberOfRecords: len(changes),
		Records:         changes,
	})
	if err != nil {
		logger.Errorf("%d GET could not json.Marshal changefeedResponse", http.StatusInternalServerError)
		return nil, errors.ErrUnknown.WithDetail(err)
	}
	return out, nil
}

func checkPendingErrors(logger context.Logger, ctx context.Context, namespace, name string) error {
	if !AuthPerformed(ctx) {
		return fmt.Errorf("openshift.auth.completed missing from context")
	}

	deferredErrors, haveDeferredErrors := DeferredErrorsFrom(ctx)
	if !haveDeferredErrors {
		return nil
	}

	repoErr, haveRepoErr := deferredErrors.Get(namespace, name)
	if !haveRepoErr {
		return nil
	}

	logger.Debugf("Origin auth: found deferred error for %s/%s: %v", namespace, name, repoErr)
	return repoErr
}

// startUploadPurger schedules a goroutine which will periodically
// check upload directories for old files and delete them
func startUploadPurger(storageDriver storagedriver.StorageDriver, log ctxu.Logger) {
	rand.Seed(time.Now().Unix())
	jitter := time.Duration(rand.Int()%60) * time.Minute

	// Start with reasonable defaults
	// TODO:(richardscothern) make configurable
	purgeAge := time.Duration(7 * 24 * time.Hour)
	timeBetweenPurges := time.Duration(1 * 24 * time.Hour)

	go func() {
		log.Infof("Starting upload purge in %s", jitter)
		time.Sleep(jitter)

		for {
			storage.PurgeUploads(storageDriver, time.Now().Add(-purgeAge), true)
			log.Infof("Starting upload purge in %s", timeBetweenPurges)
			time.Sleep(timeBetweenPurges)
		}
	}()

}

func checkChangefeedInputs(logger ctxu.Logger, s interface{}, r string) (
	store storage.MetaStore, pageSize int64, err error) {

	store, ok := s.(storage.MetaStore)
	if !ok {
		logger.Errorf("%d GET unable to retrieve storage", http.StatusInternalServerError)
		err = errors.ErrNoStorage.WithDetail(nil)
		return
	}
	pageSize, err = strconv.ParseInt(r, 10, 32)
	if err != nil {
		logger.Errorf("%d GET invalid pageSize: %s", http.StatusBadRequest, r)
		err = errors.ErrInvalidParams.WithDetail(
			fmt.Sprintf("invalid records parameter: %s", err.Error()),
		)
		return
	}
	if pageSize == 0 {
		pageSize = notary.DefaultPageSize
	}
	return
}

func serveError(log ctxu.Logger, w http.ResponseWriter, err error) {
	if httpErr, ok := err.(errcode.Error); ok {
		// info level logging for non-5XX http errors
		httpErrCode := httpErr.ErrorCode().Descriptor().HTTPStatusCode
		if httpErrCode >= http.StatusInternalServerError {
			// error level logging for 5XX http errors
			log.Errorf("%s: %s: %v", httpErr.ErrorCode().Error(), httpErr.Message, httpErr.Detail)
		} else {
			log.Infof("%s: %s: %v", httpErr.ErrorCode().Error(), httpErr.Message, httpErr.Detail)
		}
	}
	e := errcode.ServeJSON(w, err)
	if e != nil {
		log.Error(e)
	}
	return
}

// getTimestampHandler returns a timestamp.json given a GUN
func getSnapshot(ctx context.Context, w http.ResponseWriter, logger ctxu.Logger, store storage.MetaStore, gun string) error {
	cryptoServiceVal := ctx.Value("cryptoService")
	cryptoService, ok := cryptoServiceVal.(signed.CryptoService)
	if !ok {
		return errors.ErrNoCryptoService.WithDetail(nil)
	}

	out, err := snapshot.GetOrCreateSnapshot(gun, store, cryptoService)
	if err != nil {
		switch err.(type) {
		case *storage.ErrNoKey, storage.ErrNotFound:
			logger.Error("404 GET snapshot")
			return errors.ErrMetadataNotFound.WithDetail(nil)
		default:
			logger.Error("500 GET snapshot")
			return errors.ErrUnknown.WithDetail(err)
		}
	}

	logger.Debug("200 GET snapshot")
	w.Write(out)
	return nil
}

// startUploadPurger schedules a goroutine which will periodically
// check upload directories for old files and delete them
func startUploadPurger(ctx context.Context, storageDriver storagedriver.StorageDriver, log ctxu.Logger, config map[interface{}]interface{}) {
	if config["enabled"] == false {
		return
	}

	var purgeAgeDuration time.Duration
	var err error
	purgeAge, ok := config["age"]
	if ok {
		ageStr, ok := purgeAge.(string)
		if !ok {
			badPurgeUploadConfig("age is not a string")
		}
		purgeAgeDuration, err = time.ParseDuration(ageStr)
		if err != nil {
			badPurgeUploadConfig(fmt.Sprintf("Cannot parse duration: %s", err.Error()))
		}
	} else {
		badPurgeUploadConfig("age missing")
	}

	var intervalDuration time.Duration
	interval, ok := config["interval"]
	if ok {
		intervalStr, ok := interval.(string)
		if !ok {
			badPurgeUploadConfig("interval is not a string")
		}

		intervalDuration, err = time.ParseDuration(intervalStr)
		if err != nil {
			badPurgeUploadConfig(fmt.Sprintf("Cannot parse interval: %s", err.Error()))
		}
	} else {
		badPurgeUploadConfig("interval missing")
	}

	var dryRunBool bool
	dryRun, ok := config["dryrun"]
	if ok {
		dryRunBool, ok = dryRun.(bool)
		if !ok {
			badPurgeUploadConfig("cannot parse dryrun")
		}
	} else {
		badPurgeUploadConfig("dryrun missing")
	}

	go func() {
		rand.Seed(time.Now().Unix())
		jitter := time.Duration(rand.Int()%60) * time.Minute
		log.Infof("Starting upload purge in %s", jitter)
		time.Sleep(jitter)

		for {
			storage.PurgeUploads(ctx, storageDriver, time.Now().Add(-purgeAgeDuration), !dryRunBool)
			log.Infof("Starting upload purge in %s", intervalDuration)
			time.Sleep(intervalDuration)
		}
	}()
}