Implement new logic resolving before BC logic

Author: weilerN

pkg/dlx/handler.go

@@ -101,15 +101,15 @@ func (h *Handler) handleRequest(res http.ResponseWriter, req *http.Request) {
 		resourceNames = append(resourceNames, resourceName)
 		resourceTargetURLMap[resourceName] = targetURL
 	} else {
-		targetNameHeaderValue := req.Header.Get(h.targetNameHeader)
-		path := req.Header.Get(h.targetPathHeader)
-		if targetNameHeaderValue == "" {
-			h.logger.WarnWith("When ingress not set, must pass header value",
-				"missingHeader", h.targetNameHeader)
+		path, resourceNames, err := h.getResourceNameAndPath(req)
+		if err != nil {
+			h.logger.WarnWith("Failed to get resource names and path from request",
+				"error", err.Error(),
+				"host", req.Host,
+				"path", req.URL.Path)
 			res.WriteHeader(http.StatusBadRequest)
 			return
 		}
-		resourceNames = strings.Split(targetNameHeaderValue, ",")
 		for _, resourceName := range resourceNames {
 			targetURL, status := h.parseTargetURL(resourceName, path)
 			if targetURL == nil {
@@ -167,6 +167,41 @@ func (h *Handler) handleRequest(res http.ResponseWriter, req *http.Request) {
 	proxy.ServeHTTP(res, req)
 }
 
+func (h *Handler) getResourceNameAndPath(req *http.Request) (string, []string, error) {
+	if path, resourceNames, err := h.extractValuesFromIngress(req); err == nil {
+		return path, resourceNames, nil
+	} else {
+		h.logger.DebugWith("Failed to get target name from ingress cache, try to extract from the request headers",
+			"host", req.Host,
+			"path", req.URL.Path,
+			"error", err.Error())
+	}
+
+	// old implementation for backward compatibility
+	targetNameHeaderValue := req.Header.Get(h.targetNameHeader)
+	path := req.Header.Get(h.targetPathHeader)
+	if targetNameHeaderValue == "" {
+		return "", nil, errors.New("No target name header found")
+	}
+	resourceNames := strings.Split(targetNameHeaderValue, ",")
+	return path, resourceNames, nil
+}
+
+func (h *Handler) extractValuesFromIngress(req *http.Request) (string, []string, error) {
+	host := req.Host
+	path := req.URL.Path
+	resourceNames, err := h.ingressCache.Get(host, path)
+	if err != nil {
+		return "", nil, errors.New("Failed to get target name from ingress cache")
+	}
+
+	if len(resourceNames) == 0 {
+		return "", nil, errors.New("No resourceNames found in ingress cache")
+	}
+
+	return path, resourceNames, nil
+}
+
 func (h *Handler) parseTargetURL(resourceName, path string) (*url.URL, int) {
 	serviceName, err := h.resourceScaler.ResolveServiceName(scalertypes.Resource{Name: resourceName})
 	if err != nil {