lib/handshake: do not pollute logs with cannot read hello messages on TCP health checks

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1762

app/vminsert/clusternative/request_handler.go

@@ -1,6 +1,7 @@
 package clusternative
 
 import (
+	"errors"
 	"fmt"
 	"net"
 
@@ -24,6 +25,9 @@ var (
 func InsertHandler(c net.Conn) error {
 	bc, err := handshake.VMInsertServer(c, 0)
 	if err != nil {
+		if errors.Is(err, handshake.ErrIgnoreHealthcheck) {
+			return nil
+		}
 		return fmt.Errorf("cannot perform vminsert handshake with client %q: %w", c.RemoteAddr(), err)
 	}
 	return stream.Parse(bc, func(rows []storage.MetricRow) error {

app/vmstorage/servers/vminsert.go

@@ -1,6 +1,7 @@
 package servers
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"net"
@@ -73,7 +74,6 @@ func (s *VMInsertServer) run() {
 			}
 			logger.Panicf("FATAL: cannot process vminsert conns at %s: %s", s.ln.Addr(), err)
 		}
-		logger.Infof("accepted vminsert conn from %s", c.RemoteAddr())
 
 		if !s.connsMap.Add(c) {
 			// The server is closed.
@@ -98,7 +98,9 @@ func (s *VMInsertServer) run() {
 					// c is stopped inside VMInsertServer.MustStop
 					return
 				}
-				logger.Errorf("cannot perform vminsert handshake with client %q: %s", c.RemoteAddr(), err)
+				if !errors.Is(err, handshake.ErrIgnoreHealthcheck) {
+					logger.Errorf("cannot perform vminsert handshake with client %q: %s", c.RemoteAddr(), err)
+				}
 				_ = c.Close()
 				return
 			}

docs/CHANGELOG.md

@@ -32,8 +32,9 @@ The following tip changes can be tested by building VictoriaMetrics components f
 * FEATURE: do not execute the incoming request if it has been canceled by the client before the execution start. See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4223).
 * FEATURE: support time formats with timezones. For example, `2024-01-02+02:00` means `January 2, 2024` at `+02:00` time zone. See [these docs](https://docs.victoriametrics.com/#timestamp-formats).
 * FEATURE: expose `process_*` metrics at `/metrics` page of all the VictoriaMetrics components under Windows OS. See [this pull request](https://github.com/VictoriaMetrics/metrics/pull/47).
-* FEATURE: reduce the amounts of unimprotant `INFO` logging during VictoriaMetrics startup / shutdown. This should improve visibility for potentially important logs.
+* FEATURE: reduce the amounts of unimportant `INFO` logging during VictoriaMetrics startup / shutdown. This should improve visibility for potentially important logs.
 * FEATURE: upgrade base docker image (alpine) from 3.17.3 to 3.18.0. See [alpine 3.18.0 release notes](https://www.alpinelinux.org/posts/Alpine-3.18.0-released.html).
+* FEATURE: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): do not pullute logs with `cannot read hello: cannot read message with size 11: EOF` messages at `vmstorage` during TCP health checks performed by [Consul](https://developer.hashicorp.com/consul/docs/services/usage/checks) or [other services](https://docs.nginx.com/nginx/admin-guide/load-balancer/tcp-health-check/). See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1762).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): support the ability to filter [consul_sd_configs](https://docs.victoriametrics.com/sd_configs.html#consul_sd_configs) targets in more optimal way via new `filter` option. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4183).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add support for [consulagent_sd_configs](https://docs.victoriametrics.com/sd_configs.html#consulagent_sd_configs). See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3953).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): emit a warning if too small value is passed to `-remoteWrite.maxDiskUsagePerURL` command-line flag. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4195).

lib/handshake/handshake.go

@@ -1,6 +1,7 @@
 package handshake
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -55,8 +56,18 @@ func VMSelectServer(c net.Conn, compressionLevel int) (*BufferedConn, error) {
 	return genericServer(c, vmselectHello, compressionLevel)
 }
 
+// ErrIgnoreHealthcheck means the TCP healthckeck, which must be ignored.
+//
+// The TCP healthcheck is performed by opening and then immediately closing the connection.
+var ErrIgnoreHealthcheck = fmt.Errorf("TCP healthcheck - ignore it")
+
 func genericServer(c net.Conn, msg string, compressionLevel int) (*BufferedConn, error) {
 	if err := readMessage(c, msg); err != nil {
+		if errors.Is(err, io.EOF) {
+			// This is TCP healthcheck, which must be ignored in order to prevent from logs pollution.
+			// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1762
+			return nil, ErrIgnoreHealthcheck
+		}
 		return nil, fmt.Errorf("cannot read hello: %w", err)
 	}
 	if err := writeMessage(c, successResponse); err != nil {

lib/vmselectapi/server.go

@@ -198,7 +198,9 @@ func (s *Server) run() {
 					// c is closed inside Server.MustStop
 					return
 				}
-				logger.Errorf("cannot perform vmselect handshake with client %q: %s", c.RemoteAddr(), err)
+				if !errors.Is(err, handshake.ErrIgnoreHealthcheck) {
+					logger.Errorf("cannot perform vmselect handshake with client %q: %s", c.RemoteAddr(), err)
+				}
 				_ = c.Close()
 				return
 			}