Chores:

- Added CHANGELOG.md
- Added a method to support NewWith(..) to pass servicename, namespace and subsystem
- fixed failing tests

Signed-off-by: Ankur Srivastava <best.ankur@gmail.com>

CHANGELOG.md

@@ -0,0 +1,6 @@
+## Change Log
+---
+
+## [2020-07-08] - 0.3.0
+### Enhancements:
+- Support a new method to provide a namespace and a subsystem for the service

README.md

@@ -1,5 +1,5 @@
 # fiberprometheus
-  
+
 Prometheus middleware for gofiber.
 
 ![Release](https://img.shields.io/github/release/ansrivas/fiberprometheus.svg)
@@ -32,10 +32,12 @@ import (
 func main() {
   app := fiber.New()
 
+  // This here will appear as a label, one can also use
+  // fiberprometheus.NewWith(servicename, namespace, subsystem )
   prometheus := fiberprometheus.New("my-service-name")
   prometheus.RegisterAt(app, "/metrics")
   app.Use(prometheus.Middleware)
-  
+
   app.Get("/", func(c *fiber.Ctx) {
     c.Send("Hello World")
   })
@@ -47,3 +49,6 @@ func main() {
   app.Listen(3000)
 }
 ```
+### Result
+- Hit the default url at http://localhost:3000
+- Navigate to http://localhost:3000/metrics

middleware.go

@@ -19,26 +19,25 @@ type FiberPrometheus struct {
 	defaultURL      string
 }
 
-// New creates a new instance of FiberPrometheus middleware
-func New(servicename string) *FiberPrometheus {
+func create(servicename, namespace, subsystem string) *FiberPrometheus {
 	counter := promauto.NewCounterVec(
 		prometheus.CounterOpts{
-			Name:        "http_requests_total",
+			Name:        prometheus.BuildFQName(namespace, subsystem, "requests_total"),
 			Help:        "Count all http requests by status code, method and path.",
 			ConstLabels: prometheus.Labels{"service": servicename},
 		},
 		[]string{"status_code", "method", "path"},
 	)
 	histogram := promauto.NewHistogramVec(prometheus.HistogramOpts{
-		Name:        "http_request_duration_seconds",
+		Name:        prometheus.BuildFQName(namespace, subsystem, "request_duration_seconds"),
 		Help:        "Duration of all HTTP requests by status code, method and path.",
 		ConstLabels: prometheus.Labels{"service": servicename},
 	},
 		[]string{"status_code", "method", "path"},
 	)
 
 	gauge := promauto.NewGaugeVec(prometheus.GaugeOpts{
-		Name:        "http_requests_in_progress_total",
+		Name:        prometheus.BuildFQName(namespace, subsystem, "requests_in_progress_total"),
 		Help:        "All the requests in progress",
 		ConstLabels: prometheus.Labels{"service": servicename},
 	}, []string{"method", "path"})
@@ -51,6 +50,22 @@ func New(servicename string) *FiberPrometheus {
 	}
 }
 
+// New creates a new instance of FiberPrometheus middleware
+// servicename is available as a const label
+func New(servicename string) *FiberPrometheus {
+	return create(servicename, "http", "")
+}
+
+// NewWith creates a new instance of FiberPrometheus middleware but with an ability
+// to pass namespace and a custom subsystem
+// Here servicename is created as a constant-label for the metrics
+// Namespace, subsystem get prefixed to the metrics.
+// For e.g namespace = "my_app", subsyste = "http" then then metrics would be
+// my_app_http_requests_total{...,"service": servicename}
+func NewWith(servicename, namespace, subsystem string) *FiberPrometheus {
+	return create(servicename, namespace, subsystem)
+}
+
 func (ps *FiberPrometheus) handler(c *fiber.Ctx) {
 	p := fasthttpadaptor.NewFastHTTPHandler(promhttp.Handler())
 	p(c.Fasthttp)

middleware_test.go

@@ -49,13 +49,57 @@ func TestMiddleware(t *testing.T) {
 	defer resp.Body.Close()
 
 	body, _ := ioutil.ReadAll(resp.Body)
-	if !strings.Contains(string(body), `http_requests_total{method="GET",path="/",service="test-service",status_code="200"} 1`) {
-		t.Fail()
+	got := string(body)
+	want := `http_requests_total{method="GET",path="/",service="test-service",status_code="200"} 1`
+	if !strings.Contains(got, want) {
+		t.Errorf("got %s; want %s", got, want)
 	}
-	if !strings.Contains(string(body), `http_request_duration_seconds_count{method="GET",path="/",service="test-service",status_code="200"} 1`) {
-		t.Fail()
+
+	want = `http_request_duration_seconds_count{method="GET",path="/",service="test-service",status_code="200"} 1`
+	if !strings.Contains(got, want) {
+		t.Errorf("got %s; want %s", got, want)
+	}
+
+	want = `http_requests_in_progress_total{method="GET",path="/",service="test-service"} 0`
+	if !strings.Contains(got, want) {
+		t.Errorf("got %s; want %s", got, want)
+
 	}
-	if !strings.Contains(string(body), `http_requests_in_progress_total{method="GET",path="/",service="test-service"} 0`) {
+}
+
+func TestMiddlewareWithServiceName(t *testing.T) {
+	app := fiber.New()
+
+	prometheus := NewWith("test-service", "my_service", "http")
+	prometheus.RegisterAt(app, "/metrics")
+	app.Use(prometheus.Middleware)
+	app.Get("/", func(c *fiber.Ctx) {
+		c.Send("Hello World")
+	})
+	req := httptest.NewRequest("GET", "/", nil)
+	resp, _ := app.Test(req)
+	if resp.StatusCode != 200 {
 		t.Fail()
 	}
+
+	req = httptest.NewRequest("GET", "/metrics", nil)
+	resp, _ = app.Test(req)
+	defer resp.Body.Close()
+
+	body, _ := ioutil.ReadAll(resp.Body)
+	got := string(body)
+	want := `my_service_http_requests_total{method="GET",path="/",service="test-service",status_code="200"} 1`
+	if !strings.Contains(got, want) {
+		t.Errorf("got %s; want %s", got, want)
+	}
+
+	want = `my_service_http_request_duration_seconds_count{method="GET",path="/",service="test-service",status_code="200"} 1`
+	if !strings.Contains(got, want) {
+		t.Errorf("got %s; want %s", got, want)
+	}
+
+	want = `my_service_http_requests_in_progress_total{method="GET",path="/",service="test-service"} 0`
+	if !strings.Contains(got, want) {
+		t.Errorf("got %s; want %s", got, want)
+	}
 }