fix: improve error handling on non-ok response for metric server

CHANGELOG.md

@@ -43,6 +43,7 @@
 - **Datadog Scaler:** Several improvements, including a new optional parameter `metricUnavailableValue` to fill data when no Datadog metric was returned ([#2657](https://github.com/kedacore/keda/issues/2657))
 - **GCP Pubsub Scaler** Adding e2e test for GCP PubSub scaler ([#1528](https://github.com/kedacore/keda/issues/1528))
 - **Kafka Scaler** Make "disable" a valid value for tls auth parameter ([#2608](https://github.com/kedacore/keda/issues/2608))
+- **Metric API Scaler:** Improve error handling on not-ok response ([#2317](https://github.com/kedacore/keda/issues/2317))
 - **Prometheus Scaler:** Support for `X-Scope-OrgID` header in Prometheus scaler ([#2667](https://github.com/kedacore/keda/issues/2667))
 - **RabbitMQ Scaler:** Include `vhost` for RabbitMQ when retrieving queue info with `useRegex` ([#2498](https://github.com/kedacore/keda/issues/2498))
 

pkg/scalers/metrics_api_scaler.go

@@ -210,13 +210,13 @@ func (s *metricsAPIScaler) getMetricValue(ctx context.Context) (*resource.Quanti
 	if err != nil {
 		return nil, err
 	}
+	defer r.Body.Close()
 
 	if r.StatusCode != http.StatusOK {
-		msg := fmt.Sprintf("api returned %d", r.StatusCode)
+		msg := fmt.Sprintf("%s: api returned %d", r.Request.URL.Path, r.StatusCode)
 		return nil, errors.New(msg)
 	}
 
-	defer r.Body.Close()
 	b, err := ioutil.ReadAll(r.Body)
 	if err != nil {
 		return nil, err

pkg/scalers/metrics_api_scaler_test.go

@@ -3,10 +3,13 @@ package scalers
 import (
 	"context"
 	"fmt"
+	"github.com/stretchr/testify/assert"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/mock"
 )
 
 type metricsAPIMetadataTestData struct {
@@ -213,3 +216,30 @@ func TestBearerAuth(t *testing.T) {
 		t.Errorf("Error getting the metric")
 	}
 }
+
+type MockHTTPRoundTripper struct {
+	mock.Mock
+}
+
+func (m *MockHTTPRoundTripper) RoundTrip(request *http.Request) (*http.Response, error) {
+	args := m.Called(request)
+	resp := args.Get(0).(*http.Response)
+	resp.Request = request
+	return resp, args.Error(1)
+}
+
+func TestGetMetricValueErrorMessage(t *testing.T) {
+	// mock roundtripper to return non-ok status code
+	mockHTTPRoundTripper := MockHTTPRoundTripper{}
+	mockHTTPRoundTripper.On("RoundTrip", mock.Anything).Return(&http.Response{StatusCode: http.StatusTeapot}, nil)
+
+	httpClient := http.Client{Transport: &mockHTTPRoundTripper}
+	s := metricsAPIScaler{
+		metadata: &metricsAPIScalerMetadata{url: "http://dummy:1230/api/v1/"},
+		client:   &httpClient,
+	}
+
+	_, err := s.getMetricValue(context.TODO())
+
+	assert.Equal(t, err.Error(), "/api/v1/: api returned 418")
+}