From 89269b7aadcf47b7a14e27c193f16beb2f51a8bc Mon Sep 17 00:00:00 2001
From: James Mills <prologic@shortcircuit.net.au>
Date: Thu, 6 Jul 2017 01:33:31 -0700
Subject: [PATCH] Added metrics, stats and logging

---
 server.go | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 87 insertions(+), 3 deletions(-)

diff --git a/server.go b/server.go
index 68ea2d5..96aa4c1 100644
--- a/server.go
+++ b/server.go
@@ -1,12 +1,21 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"net/url"
 
+	// Logging
+	"github.com/unrolled/logger"
+
+	// Stats/Metrics
+	"github.com/rcrowley/go-metrics"
+	"github.com/rcrowley/go-metrics/exp"
+	"github.com/thoas/stats"
+
 	"github.com/GeertJohan/go.rice"
 	"github.com/julienschmidt/httprouter"
 	"github.com/patrickmn/go-cache"
@@ -15,11 +24,40 @@ import (
 	"go.iondynamics.net/templice"
 )
 
+// AcceptedTypes ...
 var AcceptedTypes = []string{
 	"text/html",
 	"text/plain",
 }
 
+// Counters ...
+type Counters struct {
+	r metrics.Registry
+}
+
+func NewCounters() *Counters {
+	counters := &Counters{
+		r: metrics.NewRegistry(),
+	}
+	return counters
+}
+
+func (c *Counters) Inc(name string) {
+	metrics.GetOrRegisterCounter(name, c.r).Inc(1)
+}
+
+func (c *Counters) Dec(name string) {
+	metrics.GetOrRegisterCounter(name, c.r).Dec(1)
+}
+
+func (c *Counters) IncBy(name string, n int64) {
+	metrics.GetOrRegisterCounter(name, c.r).Inc(n)
+}
+
+func (c *Counters) DecBy(name string, n int64) {
+	metrics.GetOrRegisterCounter(name, c.r).Dec(n)
+}
+
 // Server ...
 type Server struct {
 	bind      string
@@ -27,6 +65,13 @@ type Server struct {
 	store     *cache.Cache
 	templates *templice.Template
 	router    *httprouter.Router
+
+	// Logger
+	logger *logger.Logger
+
+	// Stats/Metrics
+	counters *Counters
+	stats    *stats.Stats
 }
 
 func (s *Server) render(w http.ResponseWriter, tmpl string, data interface{}) {
@@ -39,6 +84,8 @@ func (s *Server) render(w http.ResponseWriter, tmpl string, data interface{}) {
 // IndexHandler ...
 func (s *Server) IndexHandler() httprouter.Handle {
 	return func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+		s.counters.Inc("n_index")
+
 		accepts, err := accept.Negotiate(
 			r.Header.Get("Accept"), AcceptedTypes...,
 		)
@@ -60,6 +107,8 @@ func (s *Server) IndexHandler() httprouter.Handle {
 // PasteHandler ...
 func (s *Server) PasteHandler() httprouter.Handle {
 	return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
+		s.counters.Inc("n_paste")
+
 		var blob string
 
 		body, err := ioutil.ReadAll(r.Body)
@@ -91,7 +140,7 @@ func (s *Server) PasteHandler() httprouter.Handle {
 		uuid := shortuuid.NewWithNamespace(s.config.fqdn)
 		s.store.Set(uuid, blob, cache.DefaultExpiration)
 
-		u, err := url.Parse(fmt.Sprintf("./%s", uuid))
+		u, err := url.Parse(fmt.Sprintf("./view/%s", uuid))
 		if err != nil {
 			http.Error(w, "Internal Error", http.StatusInternalServerError)
 		}
@@ -102,6 +151,8 @@ func (s *Server) PasteHandler() httprouter.Handle {
 // ViewHandler ...
 func (s *Server) ViewHandler() httprouter.Handle {
 	return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
+		s.counters.Inc("n_view")
+
 		accepts, err := accept.Negotiate(
 			r.Header.Get("Accept"), AcceptedTypes...,
 		)
@@ -134,15 +185,37 @@ func (s *Server) ViewHandler() httprouter.Handle {
 	}
 }
 
+// StatsHandler ...
+func (s *Server) StatsHandler() httprouter.Handle {
+	return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		bs, err := json.Marshal(s.stats.Data())
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+		}
+		w.Write(bs)
+	}
+}
+
 // ListenAndServe ...
 func (s *Server) ListenAndServe() {
-	log.Fatal(http.ListenAndServe(s.bind, s.router))
+	log.Fatal(
+		http.ListenAndServe(
+			s.bind,
+			s.logger.Handler(
+				s.stats.Handler(s.router),
+			),
+		),
+	)
 }
 
 func (s *Server) initRoutes() {
+	s.router.Handler("GET", "/debug/metrics", exp.ExpHandler(s.counters.r))
+	s.router.GET("/debug/stats", s.StatsHandler())
+
 	s.router.GET("/", s.IndexHandler())
 	s.router.POST("/", s.PasteHandler())
-	s.router.GET("/:uuid", s.ViewHandler())
+	s.router.GET("/view/:uuid", s.ViewHandler())
 }
 
 // NewServer ...
@@ -153,6 +226,17 @@ func NewServer(bind string, config Config) *Server {
 		router:    httprouter.New(),
 		store:     cache.New(cfg.expiry, cfg.expiry*2),
 		templates: templice.New(rice.MustFindBox("templates")),
+
+		// Logger
+		logger: logger.New(logger.Options{
+			Prefix:               "pastebin",
+			RemoteAddressHeaders: []string{"X-Forwarded-For"},
+			OutputFlags:          log.LstdFlags,
+		}),
+
+		// Stats/Metrics
+		counters: NewCounters(),
+		stats:    stats.New(),
 	}
 
 	err := server.templates.Load()