feat(sc-52274): add status label to request_* http metrics (#249)

Co-authored-by: dmytrorezn <dmytrorezn>

Author: dmytrorezn

middleware/metrics.go

@@ -1,6 +1,8 @@
 package middleware
 
 import (
+	"strconv"
+
 	"github.com/gin-gonic/gin"
 	"github.com/prometheus/client_golang/prometheus"
 
@@ -9,9 +11,17 @@ import (
 
 const labelPath = "path"
 const labelMethod = "method"
+const labelStatus = "status"
+
+const (
+	_ = iota
+	_
+	labelStatusIndex
+)
 
 func MetricsMiddleware(namespace string, labels prometheus.Labels, reg prometheus.Registerer) gin.HandlerFunc {
-	perfMetric := metrics.NewHttpServerMetric(namespace, []string{labelPath, labelMethod}, labels, reg)
+	perfMetric := metrics.NewHttpServerMetric(namespace, []string{labelPath, labelMethod, labelStatus}, labels, reg)
+
 	return func(c *gin.Context) {
 		path := c.FullPath()
 		method := c.Request.Method
@@ -22,13 +32,21 @@ func MetricsMiddleware(namespace string, labels prometheus.Labels, reg prometheu
 			return
 		}
 
-		labelValues := []string{path, method}
+		labelValues := []string{path, method, "none"}
 
 		startTime := perfMetric.Start(labelValues...)
+
 		c.Next()
+
+		var (
+			statusCode    = c.Writer.Status()
+			statusCodeStr = strconv.FormatInt(int64(statusCode), 10)
+		)
+		labelValues[labelStatusIndex] = statusCodeStr
+
+		// record duration with status code
 		perfMetric.Duration(startTime, labelValues...)
 
-		statusCode := c.Writer.Status()
 		switch {
 		case 200 <= statusCode && statusCode <= 299:
 			perfMetric.Success(labelValues...)

middleware/metrics_test.go

@@ -27,49 +27,68 @@ func TestMetricsMiddleware(t *testing.T) {
 	router.GET("/error", func(c *gin.Context) {
 		_ = c.AbortWithError(http.StatusInternalServerError, errors.New("oops error"))
 	})
+	router.GET("/404", func(c *gin.Context) {
+		_ = c.AbortWithError(http.StatusNotFound, errors.New("404"))
+	})
 
 	// 2 successes, 1 errors
 	_ = performRequest("GET", "/success?haha=1&hoho=2", router)
 	_ = performRequest("GET", "/error?hehe=1&huhu=3", router)
 	_ = performRequest("GET", "/success/hihi", router)
+	_ = performRequest("GET", "/404", router)
 
 	metricFamilies, err := r.Gather()
 	require.NoError(t, err)
-
-	const executionFailedTotal = "execution_failed_total"
-	const executionSucceededTotal = "execution_succeeded_total"
-
+	const (
+		requestSucceededTotalKey = "request_succeeded_total"
+		requestClientErrTotalKey = "request_client_error_total"
+		requestServerErrTotalKey = "request_server_error_total"
+	)
 	// metricFamily.Name --> label --> counter value
 	expected := map[string]map[string]int{
-		executionSucceededTotal: {
+		requestSucceededTotalKey: {
 			"/success":       1,
 			"/success/:test": 1,
 			"/error":         0,
+			"/404":           0,
 		},
-		executionFailedTotal: {
+		requestServerErrTotalKey: {
 			"/success":       0,
 			"/success/:test": 0,
 			"/error":         1,
+			"/404":           0,
+		},
+		requestClientErrTotalKey: {
+			"/success":       0,
+			"/success/:test": 0,
+			"/error":         0,
+			"/404":           1,
 		},
 	}
-
 	for _, metricFamily := range metricFamilies {
 		expectedLabelCounterMap, ok := expected[*metricFamily.Name]
 		if !ok {
 			continue
 		}
-
 		require.Len(t, metricFamily.Metric, len(expectedLabelCounterMap))
 		for _, metric := range metricFamily.Metric {
-			require.Len(t, metric.Label, 2)
-			var chosenLabelIdx = -1
+			require.Len(t, metric.Label, 3)
+			labelIndexes := map[string]int{
+				labelMethod: -1,
+				labelPath:   -1,
+				labelStatus: -1,
+			}
 			for idx, label := range metric.Label {
-				if *label.Name == labelPath {
-					chosenLabelIdx = idx
-				}
+				labelIndexes[*label.Name] = idx
+			}
+			require.Equal(t, len(labelIndexes), 3)
+			for _, labelIdx := range labelIndexes {
+				require.NotEqual(t, -1, labelIdx)
 			}
-			require.NotEqual(t, -1, chosenLabelIdx)
-			require.Equal(t, float64(expectedLabelCounterMap[*metric.Label[chosenLabelIdx].Value]), *metric.Counter.Value)
+			pathIdx := labelIndexes[labelPath]
+			path := *metric.Label[pathIdx].Value
+			expectedPathMetric := float64(expectedLabelCounterMap[path])
+			require.Equal(t, expectedPathMetric, *metric.Counter.Value)
 		}
 	}
 }