now does integrated metrics! fixes #5.

thanks to @slok for setting me straight with my dumb question
on how to use his cool package:

https://github.com/slok/go-http-metrics/issues/41

httpserver/middlewares.go

@@ -6,6 +6,9 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/middleware"
+	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
+	ghmm "github.com/slok/go-http-metrics/middleware"
+	"github.com/slok/go-http-metrics/middleware/std"
 )
 
 // the following is from
@@ -78,3 +81,12 @@ func (s *server) AuthMiddleware() func(http.Handler) http.Handler {
 		})
 	}
 }
+
+func (s *server) MetricsMiddleware() func(http.Handler) http.Handler {
+	mdlw := ghmm.New(ghmm.Config{
+		Recorder: metrics.NewRecorder(metrics.Config{}),
+	})
+	return func(next http.Handler) http.Handler {
+		return std.Handler("", mdlw, next)
+	}
+}

httpserver/routes.go

@@ -1,11 +1,13 @@
 package httpserver
 
 import (
+	"net/http"
 	"time"
 
 	sentryhttp "github.com/getsentry/sentry-go/http"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 func (s *server) routes() {
@@ -20,10 +22,11 @@ func (s *server) routes() {
 
 	s.router.Use(middleware.RequestID)
 	s.router.Use(s.LoggingMiddleware())
+	s.router.Use(s.MetricsMiddleware())
 
+	// CHANGEME to suit your needs, or pull from config.
 	// timeout for request context: your handlers must finish within
 	// this window:
-	// CHANGEME to suit your needs, or pull from config.
 	s.router.Use(middleware.Timeout(60 * time.Second))
 
 	// this adds a sentry reporting middleware if and only if sentry is
@@ -32,7 +35,6 @@ func (s *server) routes() {
 	// routes are, so now it's up here.  unfortunately this cannot
 	// coexist with the normal chi Recoverer handler which prints a nice
 	// colorful stack trace to the console
-
 	if s.sentryEnabled {
 		// Options docs at
 		// https://docs.sentry.io/platforms/go/guides/http/
@@ -76,4 +78,14 @@ func (s *server) routes() {
 		s.handlePanic(),
 	)
 
+	// CHANGEME you probably want to wrap the following in some kind of
+	// auth like http basic auth which is easy to set up on your
+	// rometheus collector
+	// TODO(sneak): read http basic auth user/pass for /metrics
+	// out of environment vars
+
+	s.router.Get(
+		"/metrics",
+		http.HandlerFunc(promhttp.Handler().ServeHTTP),
+	)
 }