From e236eb74fa0d18374b77a6dbee578b3322113d12 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jes=C3=BAs=20Espino?= <jespinog@gmail.com>
Date: Fri, 20 Sep 2019 15:09:58 +0200
Subject: [PATCH] Add prometheous metrics for each api handler (#12254)

---
 api4/handlers.go       |  5 +++++
 einterfaces/metrics.go |  1 +
 web/handlers.go        | 20 ++++++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/api4/handlers.go b/api4/handlers.go
index acdf1d03d5..41bf74f758 100644
--- a/api4/handlers.go
+++ b/api4/handlers.go
@@ -18,6 +18,7 @@ func (api *API) ApiHandler(h func(*Context, http.ResponseWriter, *http.Request))
 	handler := &web.Handler{
 		GetGlobalAppOptions: api.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         web.GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      false,
 		RequireMfa:          false,
@@ -35,6 +36,7 @@ func (api *API) ApiSessionRequired(h func(*Context, http.ResponseWriter, *http.R
 	handler := &web.Handler{
 		GetGlobalAppOptions: api.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         web.GetHandlerName(h),
 		RequireSession:      true,
 		TrustRequester:      false,
 		RequireMfa:          true,
@@ -54,6 +56,7 @@ func (api *API) ApiSessionRequiredMfa(h func(*Context, http.ResponseWriter, *htt
 	handler := &web.Handler{
 		GetGlobalAppOptions: api.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         web.GetHandlerName(h),
 		RequireSession:      true,
 		TrustRequester:      false,
 		RequireMfa:          false,
@@ -73,6 +76,7 @@ func (api *API) ApiHandlerTrustRequester(h func(*Context, http.ResponseWriter, *
 	handler := &web.Handler{
 		GetGlobalAppOptions: api.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         web.GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      true,
 		RequireMfa:          false,
@@ -91,6 +95,7 @@ func (api *API) ApiSessionRequiredTrustRequester(h func(*Context, http.ResponseW
 	handler := &web.Handler{
 		GetGlobalAppOptions: api.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         web.GetHandlerName(h),
 		RequireSession:      true,
 		TrustRequester:      true,
 		RequireMfa:          true,
diff --git a/einterfaces/metrics.go b/einterfaces/metrics.go
index b604b895be..b6319225bc 100644
--- a/einterfaces/metrics.go
+++ b/einterfaces/metrics.go
@@ -44,4 +44,5 @@ type MetricsInterface interface {
 	IncrementPostsSearchCounter()
 	ObservePostsSearchDuration(elapsed float64)
 	ObserveStoreMethodDuration(method string, success string, elapsed float64)
+	ObserveApiEndpointDuration(endpoint string, elapsed float64)
 }
diff --git a/web/handlers.go b/web/handlers.go
index 9269a04e93..a666501f6d 100644
--- a/web/handlers.go
+++ b/web/handlers.go
@@ -6,6 +6,9 @@ package web
 import (
 	"fmt"
 	"net/http"
+	"reflect"
+	"runtime"
+	"strings"
 	"time"
 
 	"github.com/NYTimes/gziphandler"
@@ -16,10 +19,20 @@ import (
 	"github.com/mattermost/mattermost-server/utils"
 )
 
+func GetHandlerName(h func(*Context, http.ResponseWriter, *http.Request)) string {
+	handlerName := runtime.FuncForPC(reflect.ValueOf(h).Pointer()).Name()
+	pos := strings.LastIndex(handlerName, ".")
+	if pos != -1 && len(handlerName) > pos {
+		handlerName = handlerName[pos+1:]
+	}
+	return handlerName
+}
+
 func (w *Web) NewHandler(h func(*Context, http.ResponseWriter, *http.Request)) http.Handler {
 	return &Handler{
 		GetGlobalAppOptions: w.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      false,
 		RequireMfa:          false,
@@ -35,6 +48,7 @@ func (w *Web) NewStaticHandler(h func(*Context, http.ResponseWriter, *http.Reque
 	return &Handler{
 		GetGlobalAppOptions: w.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      false,
 		RequireMfa:          false,
@@ -47,6 +61,7 @@ func (w *Web) NewStaticHandler(h func(*Context, http.ResponseWriter, *http.Reque
 type Handler struct {
 	GetGlobalAppOptions app.AppOptionCreator
 	HandleFunc          func(*Context, http.ResponseWriter, *http.Request)
+	HandlerName         string
 	RequireSession      bool
 	TrustRequester      bool
 	RequireMfa          bool
@@ -192,6 +207,7 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path != model.API_URL_SUFFIX+"/websocket" {
 			elapsed := float64(time.Since(now)) / float64(time.Second)
 			c.App.Metrics.ObserveHttpRequestDuration(elapsed)
+			c.App.Metrics.ObserveApiEndpointDuration(h.HandlerName, elapsed)
 		}
 	}
 }
@@ -249,6 +265,7 @@ func (w *Web) ApiHandler(h func(*Context, http.ResponseWriter, *http.Request)) h
 	handler := &Handler{
 		GetGlobalAppOptions: w.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      false,
 		RequireMfa:          false,
@@ -267,6 +284,7 @@ func (w *Web) ApiHandlerTrustRequester(h func(*Context, http.ResponseWriter, *ht
 	handler := &Handler{
 		GetGlobalAppOptions: w.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      true,
 		RequireMfa:          false,
@@ -284,6 +302,7 @@ func (w *Web) ApiSessionRequired(h func(*Context, http.ResponseWriter, *http.Req
 	handler := &Handler{
 		GetGlobalAppOptions: w.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         GetHandlerName(h),
 		RequireSession:      true,
 		TrustRequester:      false,
 		RequireMfa:          true,
@@ -302,6 +321,7 @@ func (w *Web) apiHandlerTrustRequester(h func(*Context, http.ResponseWriter, *ht
 	handler := &Handler{
 		GetGlobalAppOptions: w.GetGlobalAppOptions,
 		HandleFunc:          h,
+		HandlerName:         GetHandlerName(h),
 		RequireSession:      false,
 		TrustRequester:      true,
 		RequireMfa:          false,