package net

import (
	"io"
)

// errorLabelValue returns value for Prometheus metric label "error":
// "ok" for no error, "EOF" for io.EOF, "error" otherwise.
func errorLabelValue(err error) string {
	if err == nil {
		return "ok"
	}
	if err == io.EOF {
		return "EOF"
	}
	return "error"
}

package net

func errorLabelValue(err error) string {
	if err == nil {
		return "0"
	}
	return "1"
}

--- 
+++ 
@@ -1,8 +1,17 @@
 package net
 
+import (
+	"io"
+)
+
+// errorLabelValue returns value for Prometheus metric label "error":
+// "ok" for no error, "EOF" for io.EOF, "error" otherwise.
 func errorLabelValue(err error) string {
 	if err == nil {
-		return "0"
+		return "ok"
 	}
-	return "1"
+	if err == io.EOF {
+		return "EOF"
+	}
+	return "error"
 }
Change values of «error» label.