Metrics: Ensure Stratos Metrics metadata file is optional (#4801)

* Fix link for metrics endpoints

* Ensure metrics works with plain Prometheus

* Remove test code

* Slight optimization in if

src/jetstream/plugins/metrics/main.go

@@ -182,8 +182,24 @@ func (m *MetricsSpecification) Connect(ec echo.Context, cnsiRecord interfaces.CN
 
 	var h = m.portalProxy.GetHttpClient(cnsiRecord.SkipSSLValidation)
 	res, err := h.Do(req)
+	// Error performing the request?
+	if err != nil {
+		log.Errorf("Error performing http request - response: %v, error: %v", res, err)
+		errMessage := ""
+		if res.StatusCode == http.StatusUnauthorized {
+			errMessage = ": Unauthorized"
+		}
+		return nil, false, interfaces.NewHTTPShadowError(
+			res.StatusCode,
+			fmt.Sprintf("Could not connect to the endpoint%s", errMessage),
+			"Could not connect to the endpoint: %s", err)
+	}
 
-	if err == nil && res.StatusCode == http.StatusNotFound {
+	defer res.Body.Close()
+
+	// If we got anything other than a 200, then we did not find the Stratos Metrics metadata file
+	if res.StatusCode != http.StatusOK {
+		log.Debug("Did not find Stratos Metrics metadata file")
 		log.Debug("Checking if this is a prometheus endpoint")
 		// This could be a bosh-prometheus endpoint, verify that this is a prometheus endpoint
 		statusEndpoint := fmt.Sprintf("%s/api/v1/status/config", cnsiRecord.APIEndpoint)
@@ -195,28 +211,24 @@ func (m *MetricsSpecification) Connect(ec echo.Context, cnsiRecord interfaces.CN
 		}
 		m.addAuth(req, auth)
 
+		// Get for /api/v1/status/config
 		response, err := h.Do(req)
+		if err != nil {
+			log.Errorf("Error fetching /api/v1/status/config - response: %v, error: %v", response, err)
+			return nil, false, interfaces.LogHTTPError(res, err)
+		}
+
 		defer response.Body.Close()
-		if err != nil || response.StatusCode != http.StatusOK {
-			log.Errorf("Error performing http request - response: %v, error: %v", response, err)
+		if response.StatusCode != http.StatusOK {
+			log.Errorf("Error fetching /api/v1/status/config - response: %v, error: %v", response, err)
 			return nil, false, interfaces.LogHTTPError(res, err)
 		}
 
 		tr.Metadata, _ = m.createMetadata(cnsiRecord.APIEndpoint, h, auth)
 		return tr, false, nil
-	} else if err != nil || res.StatusCode != http.StatusOK {
-		log.Errorf("Error performing http request - response: %v, error: %v", res, err)
-		errMessage := ""
-		if res.StatusCode == http.StatusUnauthorized {
-			errMessage = ": Unauthorized"
-		}
-		return nil, false, interfaces.NewHTTPShadowError(
-			res.StatusCode,
-			fmt.Sprintf("Could not connect to the endpoint%s", errMessage),
-			"Could not connect to the endpoint: %s", err)
 	}
 
-	defer res.Body.Close()
+	// We read the Stratos Metadata file ok
 	body, _ := ioutil.ReadAll(res.Body)
 	// Put the body in the token metadata
 	tr.Metadata = string(body)