From f3a43f947261a0d7b96628c6c059b89e180acc5a Mon Sep 17 00:00:00 2001
From: Shivam Sharma <shivam691999@gmail.com>
Date: Fri, 12 Nov 2021 13:13:28 +0530
Subject: [PATCH] Added Prometheus to New CLI: fixes

---
 command/server/config.go | 14 +++-------
 command/server/server.go | 57 ++++++++++++++++++++++++++--------------
 2 files changed, 40 insertions(+), 31 deletions(-)

diff --git a/command/server/config.go b/command/server/config.go
index 34fa13cf51..dd3f5dce95 100644
--- a/command/server/config.go
+++ b/command/server/config.go
@@ -88,9 +88,6 @@ type Config struct {
 
 	// GRPC has the grpc server related settings
 	GRPC *GRPCConfig
-
-	// Prometheus Server
-	Prometheus *PrometheusConfig `hcl:"prometheus,optional"`
 }
 
 type P2PConfig struct {
@@ -239,14 +236,6 @@ type GRPCConfig struct {
 	Addr string
 }
 
-type PrometheusConfig struct {
-	// Enabled selects whether the api is enabled
-	Enabled bool `hcl:"enabled,optional"`
-
-	// Host is the address to bind the api
-	address string `hcl:"host,optional"`
-}
-
 type APIConfig struct {
 	// Enabled selects whether the api is enabled
 	Enabled bool `hcl:"enabled,optional"`
@@ -286,6 +275,9 @@ type TelemetryConfig struct {
 
 	// InfluxDB has the influxdb related settings
 	InfluxDB *InfluxDBConfig `hcl:"influx,block"`
+
+	// Prometheus Address
+	PrometheusAddr string `hcl:"prometheus-addr,optional"`
 }
 
 type InfluxDBConfig struct {
diff --git a/command/server/server.go b/command/server/server.go
index 5981f0cf48..2c06804cc6 100644
--- a/command/server/server.go
+++ b/command/server/server.go
@@ -20,6 +20,7 @@ import (
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/metrics/exp"
 	"github.com/ethereum/go-ethereum/metrics/influxdb"
+	"github.com/ethereum/go-ethereum/metrics/prometheus"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/fjl/memsize/memsizeui"
 	"github.com/mattn/go-colorable"
@@ -50,11 +51,6 @@ func NewServer(config *Config) (*Server, error) {
 		return nil, err
 	}
 
-	// start the Prometheus Server
-	if err := srv.StartPrometheus(config.Prometheus.address, config.Prometheus.Enabled); err != nil {
-		return nil, err
-	}
-
 	// create the node/stack
 	nodeCfg, err := config.buildNode()
 	if err != nil {
@@ -159,6 +155,42 @@ func (s *Server) setupMetrics(config *TelemetryConfig) error {
 	// Start system runtime metrics collection
 	go metrics.CollectProcessMetrics(3 * time.Second)
 
+	// Hook go-metrics into expvar on any /debug/metrics request, load all vars
+	// from the registry into expvar, and execute regular expvar handler.
+
+	if len(config.PrometheusAddr) != 0 {
+
+		prometheusMux := http.NewServeMux()
+
+		// this would cause a panic:
+		// panic: http: multiple registrations for /debug/vars
+		// http.HandleFunc("/debug/vars", e.expHandler)
+		// haven't found an elegant way, so just use a different endpoint
+
+		prometheusMux.HandleFunc("/debug/metrics", func(w http.ResponseWriter, r *http.Request) {
+			exp.ExpHandler(metrics.DefaultRegistry)
+		})
+
+		prometheusMux.HandleFunc("/debug/metrics/prometheus", func(w http.ResponseWriter, r *http.Request) {
+			prometheus.Handler(metrics.DefaultRegistry)
+		})
+
+		promServer := &http.Server{
+			Addr:           config.PrometheusAddr,
+			Handler:        prometheusMux,
+			ReadTimeout:    10 * time.Second,
+			WriteTimeout:   10 * time.Second,
+			MaxHeaderBytes: 1 << 20,
+		}
+
+		go func() {
+			if err := promServer.ListenAndServe(); err != nil {
+				log.Error("Failure in running Prometheus server", "err", err)
+			}
+		}()
+
+	}
+
 	return nil
 }
 
@@ -182,21 +214,6 @@ func (s *Server) setupGRPCServer(addr string) error {
 }
 
 func (s *Server) StartPrometheus(address string, enabled bool) error {
-	// Hook go-metrics into expvar on any /debug/metrics request, load all vars
-	// from the registry into expvar, and execute regular expvar handler.
-	if enabled {
-		exp.Exp(metrics.DefaultRegistry)
-	}
-
-	http.Handle("/memsize/", http.StripPrefix("/memsize", &Memsize))
-
-	log.Info("Starting pprof server", "addr", fmt.Sprintf("http://%s/debug/pprof", address))
-
-	go func() {
-		if err := http.ListenAndServe(address, nil); err != nil {
-			log.Error("Failure in running pprof server", "err", err)
-		}
-	}()
 
 	return nil
 }