*: Add go runtime, process, HTTP and gRPC metrics

server/server.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/url"
 	"path"
+	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -15,8 +16,10 @@ import (
 
 	"golang.org/x/crypto/bcrypt"
 
+	"github.com/felixge/httpsnoop"
 	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
 
 	"github.com/coreos/dex/connector"
@@ -75,6 +78,8 @@ type Config struct {
 	Web WebConfig
 
 	Logger logrus.FieldLogger
+
+	PrometheusRegistry *prometheus.Registry
 }
 
 // WebConfig holds the server's frontend templates and asset configuration.
@@ -214,9 +219,26 @@ func newServer(ctx context.Context, c Config, rotationStrategy rotationStrategy)
 		}
 	}
 
+	requestCounter := prometheus.NewCounterVec(prometheus.CounterOpts{
+		Name: "http_requests_total",
+		Help: "Count of all HTTP requests.",
+	}, []string{"handler", "code", "method"})
+
+	err = c.PrometheusRegistry.Register(requestCounter)
+	if err != nil {
+		return nil, fmt.Errorf("server: Failed to register Prometheus HTTP metrics: %v", err)
+	}
+
+	instrumentHandlerCounter := func(handlerName string, handler http.Handler) http.HandlerFunc {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			m := httpsnoop.CaptureMetrics(handler, w, r)
+			requestCounter.With(prometheus.Labels{"handler": handlerName, "code": strconv.Itoa(m.Code), "method": r.Method}).Inc()
+		})
+	}
+
 	r := mux.NewRouter()
 	handleFunc := func(p string, h http.HandlerFunc) {
-		r.HandleFunc(path.Join(issuerURL.Path, p), h)
+		r.HandleFunc(path.Join(issuerURL.Path, p), instrumentHandlerCounter(p, h))
 	}
 	handlePrefix := func(p string, h http.Handler) {
 		prefix := path.Join(issuerURL.Path, p)

server/server_test.go

@@ -23,6 +23,7 @@ import (
 
 	oidc "github.com/coreos/go-oidc"
 	"github.com/kylelemons/godebug/pretty"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/crypto/bcrypt"
 	"golang.org/x/oauth2"
@@ -92,7 +93,8 @@ func newTestServer(ctx context.Context, t *testing.T, updateConfig func(c *Confi
 		Web: WebConfig{
 			Dir: filepath.Join(os.Getenv("GOPATH"), "src/github.com/coreos/dex/web"),
 		},
-		Logger: logger,
+		Logger:             logger,
+		PrometheusRegistry: prometheus.NewRegistry(),
 	}
 	if updateConfig != nil {
 		updateConfig(&config)