feat: return Retry-After header in case of 429/Too Many Requests on t…

…humbnail WebDAV endpoint

changelog/unreleased/thumbnail-request-limit.md

@@ -4,3 +4,4 @@ The number of concurrent requests to the thumbnail service can be limited now
 to have more control over the consumed system resources.
 
 https://github.com/owncloud/ocis/pull/9199
+https://github.com/owncloud/ocis/pull/9240

ocis-pkg/middleware/throttle.go

@@ -2,14 +2,28 @@ package middleware
 
 import (
 	"net/http"
+	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
 )
 
+func retryAfterFn(ctxDone bool) time.Duration {
+	if ctxDone {
+		return time.Minute
+	}
+	return time.Minute * 5
+}
+
 // Throttle limits the number of concurrent requests.
 func Throttle(limit int) func(http.Handler) http.Handler {
 	if limit > 0 {
-		return middleware.Throttle(limit)
+		opts := middleware.ThrottleOpts{
+			RetryAfterFn:   retryAfterFn,
+			Limit:          limit,
+			BacklogLimit:   0,
+			BacklogTimeout: time.Minute,
+		}
+		return middleware.ThrottleWithOpts(opts)
 	}
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

services/webdav/pkg/service/v0/service.go

@@ -454,13 +454,13 @@ func (g Webdav) sendThumbnailResponse(rsp *thumbnailssvc.GetThumbnailResponse, w
 		// Timeout: time.Second * 5,
 	}
 
-	dlReq, err := http.NewRequest(http.MethodGet, rsp.DataEndpoint, http.NoBody)
+	dlReq, err := http.NewRequest(http.MethodGet, rsp.GetDataEndpoint(), http.NoBody)
 	if err != nil {
 		renderError(w, r, errInternalError(err.Error()))
 		logger.Error().Err(err).Msg("could not create download thumbnail request")
 		return
 	}
-	dlReq.Header.Set("Transfer-Token", rsp.TransferToken)
+	dlReq.Header.Set("Transfer-Token", rsp.GetTransferToken())
 
 	dlRsp, err := client.Do(dlReq)
 	if err != nil {
@@ -470,6 +470,15 @@ func (g Webdav) sendThumbnailResponse(rsp *thumbnailssvc.GetThumbnailResponse, w
 	}
 	defer dlRsp.Body.Close()
 
+	if dlRsp.StatusCode == http.StatusTooManyRequests {
+		retryAfter := dlRsp.Header.Get("Retry-After")
+		if retryAfter != "" {
+			w.Header().Set("Retry-After", retryAfter)
+		}
+		w.WriteHeader(http.StatusTooManyRequests)
+		return
+	}
+
 	if dlRsp.StatusCode != http.StatusOK {
 		logger.Debug().
 			Str("transfer_token", rsp.GetTransferToken()).