From 4a92134235a522447102b4076b5dd680faf922cf Mon Sep 17 00:00:00 2001
From: Anis Elleuch <vadmeste@users.noreply.github.com>
Date: Mon, 12 Sep 2022 20:40:51 +0100
Subject: [PATCH] prometheus: track errors during REST read/write calls
 (#15678)

minio_inter_node_traffic_errors_total currently does not track
requests body write/read errors of internode REST communications.

This commit fixes this by wrapping resp.Body.
---
 internal/rest/client.go | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/internal/rest/client.go b/internal/rest/client.go
index e8a42b76f..b0f7e2d18 100644
--- a/internal/rest/client.go
+++ b/internal/rest/client.go
@@ -211,6 +211,26 @@ func (c *Client) newRequest(ctx context.Context, u *url.URL, body io.Reader) (*h
 	return req, nil
 }
 
+type respBodyMonitor struct {
+	io.ReadCloser
+}
+
+func (r respBodyMonitor) Read(p []byte) (n int, err error) {
+	n, err = r.ReadCloser.Read(p)
+	if err != nil && err != io.EOF {
+		atomic.AddUint64(&networkErrsCounter, 1)
+	}
+	return
+}
+
+func (r respBodyMonitor) Close() (err error) {
+	err = r.ReadCloser.Close()
+	if err != nil {
+		atomic.AddUint64(&networkErrsCounter, 1)
+	}
+	return
+}
+
 // Call - make a REST call with context.
 func (c *Client) Call(ctx context.Context, method string, values url.Values, body io.Reader, length int64) (reply io.ReadCloser, err error) {
 	urlStr := c.url.String()
@@ -286,6 +306,9 @@ func (c *Client) Call(ctx context.Context, method string, values url.Values, bod
 		}
 		return nil, errors.New(resp.Status)
 	}
+	if !c.NoMetrics && !c.ExpectTimeouts {
+		resp.Body = &respBodyMonitor{resp.Body}
+	}
 	return resp.Body, nil
 }