PMM-4274 Enable pprof (#488)

* PMM-4274 Enable pprof

This patch will enable pprof for the MongoDB exporter.

* Added gci to make format

* Updated Makefile to use cgi

* Ran format

Author: percona-csalguero

Makefile

@@ -84,7 +84,7 @@ FILES = $(shell find . -type f -name '*.go' -not -path "./vendor/*")
 format:                     ## Format source code.
 	go mod tidy
 	bin/gofumpt -l -w $(FILES)
-	bin/goimports -local github.com/percona/mongodb_exporter -l -w $(FILES)
+	bin/gci write --Section Standard --Section Default --Section "Prefix(github.com/percona/mongodb_exporter)" .
 
 check:                      ## Run checks/linters
 	bin/golangci-lint run

exporter/exporter.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	_ "net/http/pprof"
 	"os"
 	"strconv"
 	"sync"
@@ -322,9 +323,12 @@ func (e *Exporter) Handler() http.Handler {
 
 // Run starts the exporter.
 func (e *Exporter) Run() {
+	mux := http.DefaultServeMux
+	mux.Handle("/metrics", e.Handler())
+
 	server := &http.Server{
 		Addr:    e.webListenAddress,
-		Handler: e.Handler(),
+		Handler: mux,
 	}
 
 	if err := web.ListenAndServe(server, e.opts.TLSConfigPath, promlog.New(&promlog.Config{})); err != nil {

tools/tools.go

@@ -20,14 +20,14 @@
 package tools
 
 import (
+	_ "github.com/daixiang0/gci"
 	_ "github.com/golangci/golangci-lint/cmd/golangci-lint"
 	_ "github.com/reviewdog/reviewdog/cmd/reviewdog"
-	_ "golang.org/x/tools/cmd/goimports"
 	_ "mvdan.cc/gofumpt"
 )
 
 // tools
+//go:generate go build -o ../bin/gci github.com/daixiang0/gci
 //go:generate go build -o ../bin/gofumpt mvdan.cc/gofumpt
 //go:generate go build -o ../bin/golangci-lint github.com/golangci/golangci-lint/cmd/golangci-lint
 //go:generate go build -o ../bin/reviewdog github.com/reviewdog/reviewdog/cmd/reviewdog
-//go:generate go build -o ../bin/goimports golang.org/x/tools/cmd/goimports