fix global cache returning duplicate responses (TykTechnologies#2871)

fixes TykTechnologies#2832

gateway/gateway_test.go

@@ -2064,3 +2064,29 @@ func TestStripRegex(t *testing.T) {
 		}
 	}
 }
+
+func TestCache_singleErrorResponse(t *testing.T) {
+	ts := StartTest()
+	defer ts.Close()
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	defer srv.Close()
+	BuildAndLoadAPI(func(spec *APISpec) {
+		spec.UseKeylessAccess = true
+		spec.Proxy.ListenPath = "/"
+		spec.Proxy.TargetURL = srv.URL
+		spec.CacheOptions.CacheTimeout = 1
+		spec.CacheOptions.EnableCache = true
+		spec.CacheOptions.CacheAllSafeRequests = true
+	})
+	ts.Run(t,
+		test.TestCase{Method: http.MethodGet, Path: "/", Code: http.StatusOK},
+	)
+	time.Sleep(time.Second)
+	srv.Close()
+	wantBody := `{
+    "error": "There was a problem proxying the request"
+}`
+	ts.Run(t,
+		test.TestCase{Method: http.MethodGet, Path: "/", Code: http.StatusInternalServerError, BodyMatch: wantBody},
+	)
+}

gateway/handler_success.go

@@ -343,7 +343,7 @@ func (s *SuccessHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) *http
 // ServeHTTPWithCache will store the request details in the analytics store if necessary and proxy the request to it's
 // final destination, this is invoked by the ProxyHandler or right at the start of a request chain if the URL
 // Spec states the path is Ignored Itwill also return a response object for the cache
-func (s *SuccessHandler) ServeHTTPWithCache(w http.ResponseWriter, r *http.Request) *http.Response {
+func (s *SuccessHandler) ServeHTTPWithCache(w http.ResponseWriter, r *http.Request) ProxyResponse {
 
 	versionDef := s.Spec.VersionDefinition
 	if !s.Spec.VersionData.NotVersioned && versionDef.Location == "url" && versionDef.StripPath {
@@ -377,5 +377,5 @@ func (s *SuccessHandler) ServeHTTPWithCache(w http.ResponseWriter, r *http.Reque
 		s.RecordHit(r, latency, inRes.Response.StatusCode, inRes.Response)
 	}
 
-	return inRes.Response
+	return inRes
 }

gateway/mw_redis_cache.go

@@ -239,15 +239,16 @@ func (m *RedisCacheMiddleware) ProcessRequest(w http.ResponseWriter, r *http.Req
 				r.Method = newMethod
 				ctxSetTransformRequestMethod(r, "")
 			}
-			resVal = m.sh.ServeHTTPWithCache(w, r)
+			sr := m.sh.ServeHTTPWithCache(w, r)
+			resVal = sr.Response
 		}
 
 		cacheThisRequest := true
 		cacheTTL := m.Spec.CacheOptions.CacheTimeout
 
 		if resVal == nil {
 			log.Warning("Upstream request must have failed, response is empty")
-			return nil, http.StatusOK
+			return nil, mwStatusRespond
 		}
 
 		cacheOnlyResponseCodes := m.Spec.CacheOptions.CacheOnlyResponseCodes

gateway/reverse_proxy.go

@@ -443,7 +443,6 @@ var hopHeaders = []string{
 func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) ProxyResponse {
 	startTime := time.Now()
 	p.logger.WithField("ts", startTime.UnixNano()).Debug("Started")
-
 	resp := p.WrappedServeHTTP(rw, req, recordDetail(req, p.TykAPISpec))
 
 	finishTime := time.Since(startTime)
@@ -461,7 +460,6 @@ func (p *ReverseProxy) ServeHTTPForCache(rw http.ResponseWriter, req *http.Reque
 
 	resp := p.WrappedServeHTTP(rw, req, true)
 	nopCloseResponseBody(resp.Response)
-
 	finishTime := time.Since(startTime)
 	p.logger.WithField("ns", finishTime.Nanoseconds()).Debug("Finished")
 
@@ -675,7 +673,6 @@ func (p *ReverseProxy) WrappedServeHTTP(rw http.ResponseWriter, req *http.Reques
 		ext.SpanKindRPCClient.Set(span)
 		req = req.WithContext(ctx)
 	}
-
 	var roundTripper http.RoundTripper
 
 	p.TykAPISpec.Lock()
@@ -860,7 +857,6 @@ func (p *ReverseProxy) WrappedServeHTTP(rw http.ResponseWriter, req *http.Reques
 			"org_id":      p.TykAPISpec.OrgID,
 			"api_id":      p.TykAPISpec.APIID,
 		}).Error("http: proxy error: ", err)
-
 		if strings.Contains(err.Error(), "timeout awaiting response headers") {
 			p.ErrorHandler.HandleError(rw, logreq, "Upstream service reached hard timeout.", http.StatusGatewayTimeout, true)
 
@@ -882,7 +878,6 @@ func (p *ReverseProxy) WrappedServeHTTP(rw http.ResponseWriter, req *http.Reques
 			p.ErrorHandler.HandleError(rw, logreq, "Upstream host lookup failed", http.StatusInternalServerError, true)
 			return ProxyResponse{UpstreamLatency: upstreamLatency}
 		}
-
 		p.ErrorHandler.HandleError(rw, logreq, "There was a problem proxying the request", http.StatusInternalServerError, true)
 		return ProxyResponse{UpstreamLatency: upstreamLatency}