[#44] Expose metrics

Signed-off-by: Denis Kirillov <denis@nspcc.ru>

metrics/pprof.go

@@ -0,0 +1,33 @@
+package metrics
+
+import (
+	"net/http"
+	"net/http/pprof"
+
+	"go.uber.org/zap"
+)
+
+// NewPprofService creates a new service for gathering pprof metrics.
+func NewPprofService(l *zap.Logger, cfg Config) *Service {
+	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)
+
+	// Manually add support for paths linked to by index page at /debug/pprof/
+	for _, item := range []string{"allocs", "block", "heap", "goroutine", "mutex", "threadcreate"} {
+		handler.Handle("/debug/pprof/"+item, pprof.Handler(item))
+	}
+
+	return &Service{
+		Server: &http.Server{
+			Addr:    cfg.Address,
+			Handler: handler,
+		},
+		enabled:     cfg.Enabled,
+		serviceType: "Pprof",
+		log:         l.With(zap.String("service", "Pprof")),
+	}
+}