[#171] Sync metrics and pprof configuration

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

metrics/metrics.go

@@ -0,0 +1,68 @@
+package metrics
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.uber.org/zap"
+)
+
+const (
+	namespace      = "neofs_http_gw"
+	stateSubsystem = "state"
+)
+
+type GateMetrics struct {
+	stateMetrics
+}
+
+type stateMetrics struct {
+	healthCheck prometheus.Gauge
+}
+
+// NewGateMetrics creates new metrics for http gate.
+func NewGateMetrics() *GateMetrics {
+	stateMetric := newStateMetrics()
+	stateMetric.register()
+
+	return &GateMetrics{
+		stateMetrics: *stateMetric,
+	}
+}
+
+func newStateMetrics() *stateMetrics {
+	return &stateMetrics{
+		healthCheck: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: stateSubsystem,
+			Name:      "health",
+			Help:      "Current HTTP gateway state",
+		}),
+	}
+}
+
+func (m stateMetrics) register() {
+	prometheus.MustRegister(m.healthCheck)
+}
+
+func (m stateMetrics) SetHealth(s int32) {
+	m.healthCheck.Set(float64(s))
+}
+
+// NewPrometheusService creates a new service for gathering prometheus metrics.
+func NewPrometheusService(log *zap.Logger, cfg Config) *Service {
+	if log == nil {
+		return nil
+	}
+
+	return &Service{
+		Server: &http.Server{
+			Addr:    cfg.Address,
+			Handler: promhttp.Handler(),
+		},
+		enabled:     cfg.Enabled,
+		serviceType: "Prometheus",
+		log:         log.With(zap.String("service", "Prometheus")),
+	}
+}