fix(inputs.socket_listener): Avoid noisy logs on closed connection (#13288)

plugins/inputs/socket_listener/socket_listener_test.go

@@ -136,8 +136,9 @@ func TestSocketListener(t *testing.T) {
 			}
 
 			// Setup plugin according to test specification
+			logger := &testutil.CaptureLogger{}
 			plugin := &SocketListener{
-				Log:             &testutil.Logger{},
+				Log:             logger,
 				ServiceAddress:  proto + "://" + serverAddr,
 				ContentEncoding: tt.encoding,
 				ReadBufferSize:  tt.buffersize,
@@ -158,10 +159,17 @@ func TestSocketListener(t *testing.T) {
 			require.NoError(t, plugin.Start(&acc))
 			defer plugin.Stop()
 
-			// Setup the client for submitting data
 			addr := plugin.listener.addr()
+
+			// Create a noop client
+			// Server is async, so verify no errors at the end.
 			client, err := createClient(plugin.ServiceAddress, addr, tlsCfg)
 			require.NoError(t, err)
+			require.NoError(t, client.Close())
+
+			// Setup the client for submitting data
+			client, err = createClient(plugin.ServiceAddress, addr, tlsCfg)
+			require.NoError(t, err)
 
 			// Send the data with the correct encoding
 			encoder, err := internal.NewContentEncoder(tt.encoding)
@@ -189,6 +197,8 @@ func TestSocketListener(t *testing.T) {
 
 			plugin.Stop()
 
+			// Make sure we clear out old messages
+			logger.Clear()
 			if _, ok := plugin.listener.(*streamListener); ok {
 				// Verify that plugin.Stop() closed the client's connection
 				_ = client.SetReadDeadline(time.Now().Add(time.Second))
@@ -196,6 +206,9 @@ func TestSocketListener(t *testing.T) {
 				_, err = client.Read(buf)
 				require.Equal(t, err, io.EOF)
 			}
+
+			require.Empty(t, logger.Errors())
+			require.Empty(t, logger.Warnings())
 		})
 	}
 }

plugins/inputs/socket_listener/stream_listener.go

@@ -5,11 +5,13 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
+	"io"
 	"net"
 	"net/url"
 	"os"
 	"strconv"
 	"sync"
+	"syscall"
 	"time"
 
 	"github.com/influxdata/telegraf"
@@ -133,7 +135,7 @@ func (l *streamListener) setupConnection(conn net.Conn) error {
 
 func (l *streamListener) closeConnection(conn net.Conn) {
 	addr := conn.RemoteAddr().String()
-	if err := conn.Close(); err != nil {
+	if err := conn.Close(); err != nil && !errors.Is(err, net.ErrClosed) && !errors.Is(err, syscall.EPIPE) {
 		l.Log.Warnf("Cannot close connection to %q: %v", addr, err)
 	}
 	delete(l.connections, conn)
@@ -190,7 +192,9 @@ func (l *streamListener) listen(acc telegraf.Accumulator) {
 		go func(c net.Conn) {
 			defer wg.Done()
 			if err := l.read(acc, c); err != nil {
-				acc.AddError(err)
+				if !errors.Is(err, io.EOF) && !errors.Is(err, syscall.ECONNRESET) {
+					acc.AddError(err)
+				}
 			}
 			l.Lock()
 			l.closeConnection(conn)

testutil/capturelog.go

@@ -127,3 +127,9 @@ func (l *CaptureLogger) LastError() string {
 	}
 	return ""
 }
+
+func (l *CaptureLogger) Clear() {
+	l.Lock()
+	defer l.Unlock()
+	l.messages = make([]Entry, 0)
+}