metrics: add initial Prometheus support (#4141)

cmd/web.go

@@ -25,6 +25,7 @@ import (
 	"github.com/go-macaron/session"
 	"github.com/go-macaron/toolbox"
 	"github.com/mcuadros/go-version"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/urfave/cli"
 	log "gopkg.in/clog.v1"
 	"gopkg.in/macaron.v1"
@@ -260,11 +261,11 @@ func runWeb(c *cli.Context) error {
 	})
 	// ***** END: User *****
 
-	adminReq := context.Toggle(&context.ToggleOptions{SignInRequired: true, AdminRequired: true})
+	reqAdmin := context.Toggle(&context.ToggleOptions{SignInRequired: true, AdminRequired: true})
 
 	// ***** START: Admin *****
 	m.Group("/admin", func() {
-		m.Get("", adminReq, admin.Dashboard)
+		m.Get("", admin.Dashboard)
 		m.Get("/config", admin.Config)
 		m.Post("/config/test_mail", admin.SendTestMail)
 		m.Get("/monitor", admin.Monitor)
@@ -298,7 +299,7 @@ func runWeb(c *cli.Context) error {
 			m.Post("/delete", admin.DeleteNotices)
 			m.Get("/empty", admin.EmptyNotices)
 		})
-	}, adminReq)
+	}, reqAdmin)
 	// ***** END: Admin *****
 
 	m.Group("", func() {
@@ -659,6 +660,18 @@ func runWeb(c *cli.Context) error {
 		apiv1.RegisterRoutes(m)
 	}, ignSignIn)
 
+	m.Group("/-", func() {
+		if setting.Prometheus.Enabled {
+			m.Get("/metrics", func(c *context.Context) {
+				if !setting.Prometheus.EnableBasicAuth {
+					return
+				}
+
+				c.RequireBasicAuth(setting.Prometheus.BasicAuthUsername, setting.Prometheus.BasicAuthPassword)
+			}, promhttp.Handler())
+		}
+	})
+
 	// robots.txt
 	m.Get("/robots.txt", func(c *context.Context) {
 		if setting.HasRobotsTxt {