feat(pprof): add pprof HTTP server (#807)

- `PPROF_ENABLED=no`
- `PPROF_BLOCK_PROFILE_RATE=0`
- `PPROF_MUTEX_PROFILE_RATE=0`
- `PPROF_HTTP_SERVER_ADDRESS=":6060"`

internal/pprof/server.go

@@ -0,0 +1,40 @@
+package pprof
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/pprof"
+	"runtime"
+
+	"github.com/qdm12/gluetun/internal/httpserver"
+)
+
+// New creates a new Pprof server and configure profiling
+// with the settings given. It returns an error
+// if one of the settings is not valid.
+func New(settings Settings) (server *httpserver.Server, err error) {
+	runtime.SetBlockProfileRate(settings.BlockProfileRate)
+	runtime.SetMutexProfileFraction(settings.MutexProfileRate)
+
+	handler := http.NewServeMux()
+	handler.HandleFunc("/debug/pprof/", pprof.Index)
+	handler.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
+	handler.HandleFunc("/debug/pprof/profile", pprof.Profile)
+	handler.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
+	handler.HandleFunc("/debug/pprof/trace", pprof.Trace)
+	handler.Handle("/debug/pprof/block", pprof.Handler("block"))
+	handler.Handle("/debug/pprof/goroutine", pprof.Handler("goroutine"))
+	handler.Handle("/debug/pprof/heap", pprof.Handler("heap"))
+	handler.Handle("/debug/pprof/threadcreate", pprof.Handler("threadcreate"))
+
+	httpServerName := "pprof"
+	settings.HTTPServer.Name = &httpServerName
+	settings.HTTPServer.Handler = handler
+
+	settings.SetDefaults()
+	if err = settings.Validate(); err != nil {
+		return nil, fmt.Errorf("pprof settings failed validation: %w", err)
+	}
+
+	return httpserver.New(settings.HTTPServer)
+}