Support custom labels

.gitignore

@@ -1,2 +1,4 @@
 vendor/
-.test_coverage.txt
+.test_coverage.txt
+
+.idea/

go.mod

@@ -1,5 +1,7 @@
 module github.com/slok/go-http-metrics
 
+go 1.17
+
 require (
 	contrib.go.opencensus.io/exporter/prometheus v0.4.0
 	github.com/emicklei/go-restful/v3 v3.7.2
@@ -90,5 +92,3 @@ require (
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )
-
-go 1.17

internal/mocks/doc.go

@@ -3,5 +3,6 @@ Package mocks will have all the mocks of the library.
 */
 package mocks // import "github.com/slok/go-http-metrics/internal/mocks"
 
-//go:generate mockery -output ./metrics -outpkg metrics -dir ../../metrics -name Recorder
-//go:generate mockery -output ./middleware -outpkg middleware -dir ../../middleware -name Reporter
+//go:generate mockery --output ./metrics --outpkg metrics --dir ../../metrics --name Recorder
+//go:generate mockery --output ./middleware --outpkg middleware --dir ../../middleware --name Reporter
+//go:generate mockery --output ./middleware --outpkg middleware --dir ../../middleware --name CustomLabelReporter

metrics/metrics.go

@@ -16,6 +16,9 @@ type HTTPReqProperties struct {
 	Method string
 	// Code is the response of the request.
 	Code string
+
+	// CustomLabels hold values of the custom labels, if any.
+	CustomLabels []string
 }
 
 // HTTPProperties are the metric properties for the global server metrics.
@@ -24,6 +27,9 @@ type HTTPProperties struct {
 	Service string
 	// ID is the id of the request handler.
 	ID string
+
+	// CustomLabels hold values of the custom labels, if any.
+	CustomLabels []string
 }
 
 // Recorder knows how to record and measure the metrics. This

metrics/prometheus/prometheus.go

@@ -30,6 +30,9 @@ type Config struct {
 	MethodLabel string
 	// ServiceLabel is the name that will be set to the service label, by default is `service`.
 	ServiceLabel string
+
+	// CustomLabels hold names of the custom labels, if any.
+	CustomLabels []string
 }
 
 func (c *Config) defaults() {
@@ -73,29 +76,47 @@ type recorder struct {
 func NewRecorder(cfg Config) metrics.Recorder {
 	cfg.defaults()
 
+	perReqLabels := append(
+		[]string{
+			cfg.ServiceLabel,
+			cfg.HandlerIDLabel,
+			cfg.MethodLabel,
+			cfg.StatusCodeLabel,
+		},
+		cfg.CustomLabels...,
+	)
+
+	serviceLabels := append(
+		[]string{
+			cfg.ServiceLabel,
+			cfg.HandlerIDLabel,
+		},
+		cfg.CustomLabels...,
+	)
+
 	r := &recorder{
 		httpRequestDurHistogram: prometheus.NewHistogramVec(prometheus.HistogramOpts{
 			Namespace: cfg.Prefix,
 			Subsystem: "http",
 			Name:      "request_duration_seconds",
 			Help:      "The latency of the HTTP requests.",
 			Buckets:   cfg.DurationBuckets,
-		}, []string{cfg.ServiceLabel, cfg.HandlerIDLabel, cfg.MethodLabel, cfg.StatusCodeLabel}),
+		}, perReqLabels),
 
 		httpResponseSizeHistogram: prometheus.NewHistogramVec(prometheus.HistogramOpts{
 			Namespace: cfg.Prefix,
 			Subsystem: "http",
 			Name:      "response_size_bytes",
 			Help:      "The size of the HTTP responses.",
 			Buckets:   cfg.SizeBuckets,
-		}, []string{cfg.ServiceLabel, cfg.HandlerIDLabel, cfg.MethodLabel, cfg.StatusCodeLabel}),
+		}, perReqLabels),
 
 		httpRequestsInflight: prometheus.NewGaugeVec(prometheus.GaugeOpts{
 			Namespace: cfg.Prefix,
 			Subsystem: "http",
 			Name:      "requests_inflight",
 			Help:      "The number of inflight requests being handled at the same time.",
-		}, []string{cfg.ServiceLabel, cfg.HandlerIDLabel}),
+		}, serviceLabels),
 	}
 
 	cfg.Registry.MustRegister(
@@ -108,13 +129,19 @@ func NewRecorder(cfg Config) metrics.Recorder {
 }
 
 func (r recorder) ObserveHTTPRequestDuration(_ context.Context, p metrics.HTTPReqProperties, duration time.Duration) {
-	r.httpRequestDurHistogram.WithLabelValues(p.Service, p.ID, p.Method, p.Code).Observe(duration.Seconds())
+	lvs := []string{p.Service, p.ID, p.Method, p.Code}
+	lvs = append(lvs, p.CustomLabels...)
+	r.httpRequestDurHistogram.WithLabelValues(lvs...).Observe(duration.Seconds())
 }
 
 func (r recorder) ObserveHTTPResponseSize(_ context.Context, p metrics.HTTPReqProperties, sizeBytes int64) {
-	r.httpResponseSizeHistogram.WithLabelValues(p.Service, p.ID, p.Method, p.Code).Observe(float64(sizeBytes))
+	lvs := []string{p.Service, p.ID, p.Method, p.Code}
+	lvs = append(lvs, p.CustomLabels...)
+	r.httpResponseSizeHistogram.WithLabelValues(lvs...).Observe(float64(sizeBytes))
 }
 
 func (r recorder) AddInflightRequests(_ context.Context, p metrics.HTTPProperties, quantity int) {
-	r.httpRequestsInflight.WithLabelValues(p.Service, p.ID).Add(float64(quantity))
+	lvs := []string{p.Service, p.ID}
+	lvs = append(lvs, p.CustomLabels...)
+	r.httpRequestsInflight.WithLabelValues(lvs...).Add(float64(quantity))
 }

metrics/prometheus/prometheus_test.go

@@ -159,7 +159,7 @@ func TestPrometheusRecorder(t *testing.T) {
 			},
 		},
 		{
-			name: "Using a custom labels in the configuration should measure with those labels.",
+			name: "Using a custom label names in the configuration should measure with those labels.",
 			config: libprometheus.Config{
 				HandlerIDLabel:  "route_id",
 				StatusCodeLabel: "status_code",
@@ -186,12 +186,38 @@ func TestPrometheusRecorder(t *testing.T) {
 				`http_request_duration_seconds_count{http_method="GET",http_service="svc1",route_id="test1",status_code="200"} 2`,
 			},
 		},
+		{
+			name: "Using a custom labels in the configuration should measure with those labels.",
+			config: libprometheus.Config{
+				DurationBuckets: []float64{1, 10},
+				CustomLabels:    []string{"user_id"},
+			},
+			recordMetrics: func(r metrics.Recorder) {
+				r.ObserveHTTPRequestDuration(context.TODO(), metrics.HTTPReqProperties{
+					Service:      "svc1",
+					ID:           "test1",
+					Method:       http.MethodGet,
+					Code:         "200",
+					CustomLabels: []string{"userVIP"},
+				}, 6*time.Second)
+				r.AddInflightRequests(context.TODO(), metrics.HTTPProperties{
+					Service:      "svc1",
+					ID:           "test1",
+					CustomLabels: []string{"userVIP"},
+				}, 1)
+			},
+			expMetrics: []string{
+				`http_request_duration_seconds_bucket{code="200",handler="test1",method="GET",service="svc1",user_id="userVIP",le="1"} 0`,
+				`http_request_duration_seconds_bucket{code="200",handler="test1",method="GET",service="svc1",user_id="userVIP",le="10"} 1`,
+				`http_request_duration_seconds_bucket{code="200",handler="test1",method="GET",service="svc1",user_id="userVIP",le="+Inf"} 1`,
+				`http_request_duration_seconds_count{code="200",handler="test1",method="GET",service="svc1",user_id="userVIP"} 1`,
+				`http_requests_inflight{handler="test1",service="svc1",user_id="userVIP"} 1`,
+			},
+		},
 	}
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			assert := assert.New(t)
-
 			reg := prometheus.NewRegistry()
 			test.config.Registry = reg
 			mrecorder := libprometheus.NewRecorder(test.config)
@@ -205,10 +231,10 @@ func TestPrometheusRecorder(t *testing.T) {
 			resp := rec.Result()
 
 			// Check all metrics are present.
-			if assert.Equal(http.StatusOK, resp.StatusCode) {
+			if assert.Equal(t, http.StatusOK, resp.StatusCode) {
 				body, _ := ioutil.ReadAll(resp.Body)
 				for _, expMetric := range test.expMetrics {
-					assert.Contains(string(body), expMetric, "metric not present on the result")
+					assert.Contains(t, string(body), expMetric, "metric not present on the result")
 				}
 			}
 		})