feat: add API to return list of objects waiting to be replicated (#15091)

cmd/admin-bucket-handlers.go

@@ -383,6 +383,7 @@ func (a adminAPIHandlers) ExportBucketMetadataHandler(w http.ResponseWriter, r *
 	if objectAPI == nil {
 		return
 	}
+
 	var (
 		buckets []BucketInfo
 		err     error
@@ -1060,3 +1061,79 @@ func (a adminAPIHandlers) ImportBucketMetadataHandler(w http.ResponseWriter, r *
 		}
 	}
 }
+
+// ReplicationDiffHandler - POST returns info on unreplicated versions for a remote target ARN
+// to the connected HTTP client. This is a MinIO only extension
+func (a adminAPIHandlers) ReplicationDiffHandler(w http.ResponseWriter, r *http.Request) {
+	ctx := newContext(r, w, "ReplicationDiff")
+	defer logger.AuditLog(ctx, w, r, mustGetClaimsFromToken(r))
+
+	vars := mux.Vars(r)
+	bucket := vars["bucket"]
+
+	if globalIsGateway {
+		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrNotImplemented), r.URL)
+		return
+	}
+
+	// Get current object layer instance.
+	objectAPI := newObjectLayerFn()
+	if objectAPI == nil {
+		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrServerNotInitialized), r.URL)
+		return
+	}
+	// check if user has permissions to perform this operation
+	if s3Error := checkRequestAuthType(ctx, r, policy.ListBucketVersionsAction, bucket, ""); s3Error != ErrNone {
+		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
+		return
+	}
+
+	// Check if bucket exists.
+	if _, err := objectAPI.GetBucketInfo(ctx, bucket); err != nil {
+		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+		return
+	}
+	opts := extractReplicateDiffOpts(r.Form)
+	if opts.ARN != "" {
+		tgt := globalBucketTargetSys.GetRemoteBucketTargetByArn(ctx, bucket, opts.ARN)
+		if tgt.Empty() {
+			writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErrWithErr(ErrInvalidRequest, fmt.Errorf("invalid arn : '%s'", opts.ARN)), r.URL)
+			return
+		}
+	}
+
+	keepAliveTicker := time.NewTicker(500 * time.Millisecond)
+	defer keepAliveTicker.Stop()
+
+	diffCh, err := getReplicationDiff(ctx, objectAPI, bucket, opts)
+	if err != nil {
+		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+		return
+	}
+	enc := json.NewEncoder(w)
+	for {
+		select {
+		case entry, ok := <-diffCh:
+			if !ok {
+				return
+			}
+			if err := enc.Encode(entry); err != nil {
+				return
+			}
+			if len(diffCh) == 0 {
+				// Flush if nothing is queued
+				w.(http.Flusher).Flush()
+			}
+		case <-keepAliveTicker.C:
+			if len(diffCh) > 0 {
+				continue
+			}
+			if _, err := w.Write([]byte(" ")); err != nil {
+				return
+			}
+			w.(http.Flusher).Flush()
+		case <-ctx.Done():
+			return
+		}
+	}
+}