[#370] Add tree service metrics

Signed-off-by: Alejandro Lopez <a.lopez@yadro.com>

pkg/services/tree/options.go

@@ -33,6 +33,8 @@ type cfg struct {
 	replicatorWorkerCount     int
 	replicatorTimeout         time.Duration
 	containerCacheSize        int
+
+	metrics MetricsRegister
 }
 
 // Option represents configuration option for a tree service.
@@ -116,3 +118,9 @@ func WithReplicationTimeout(t time.Duration) Option {
 		}
 	}
 }
+
+func WithMetrics(v MetricsRegister) Option {
+	return func(c *cfg) {
+		c.metrics = v
+	}
+}