Add hostname to default tracing tags

tracing/tracing.go

@@ -77,11 +77,13 @@ func getServiceName() string {
 }
 
 func defaultResource(serviceName string) *resource.Resource {
+	hostname, _ := os.Hostname()
 	r, _ := resource.Merge(
 		resource.Default(),
 		resource.NewWithAttributes(
 			semconv.SchemaURL,
 			semconv.ServiceNameKey.String(serviceName),
+			semconv.HostNameKey.String(hostname),
 		),
 	)
 	return r