socket_listener: clean up unix socket file on start & stop (#2618)

plugins/inputs/socket_listener/socket_listener.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"log"
 	"net"
+	"os"
 	"strings"
 	"sync"
 
@@ -32,7 +33,9 @@ func (ssl *streamSocketListener) listen() {
 	for {
 		c, err := ssl.Accept()
 		if err != nil {
+			if !strings.HasSuffix(err.Error(), ": use of closed network connection") {
 				ssl.AddError(err)
+			}
 			break
 		}
 
@@ -78,8 +81,10 @@ func (ssl *streamSocketListener) read(c net.Conn) {
 	}
 
 	if err := scnr.Err(); err != nil {
+		if !strings.HasSuffix(err.Error(), ": use of closed network connection") {
 			ssl.AddError(err)
 		}
+	}
 }
 
 type packetSocketListener struct {
@@ -92,7 +97,9 @@ func (psl *packetSocketListener) listen() {
 	for {
 		n, _, err := psl.ReadFrom(buf)
 		if err != nil {
+			if !strings.HasSuffix(err.Error(), ": use of closed network connection") {
 				psl.AddError(err)
+			}
 			break
 		}
 
@@ -170,6 +177,13 @@ func (sl *SocketListener) Start(acc telegraf.Accumulator) error {
 		return fmt.Errorf("invalid service address: %s", sl.ServiceAddress)
 	}
 
+	if spl[0] == "unix" || spl[0] == "unixpacket" || spl[0] == "unixgram" {
+		// no good way of testing for "file does not exist".
+		// Instead just ignore error and blow up when we try to listen, which will
+		// indicate "address already in use" if file existed and we couldn't remove.
+		os.Remove(spl[1])
+	}
+
 	switch spl[0] {
 	case "tcp", "tcp4", "tcp6", "unix", "unixpacket":
 		l, err := net.Listen(spl[0], spl[1])
@@ -217,6 +231,10 @@ func (sl *SocketListener) Start(acc telegraf.Accumulator) error {
 		return fmt.Errorf("unknown protocol '%s' in '%s'", spl[0], sl.ServiceAddress)
 	}
 
+	if spl[0] == "unix" || spl[0] == "unixpacket" || spl[0] == "unixgram" {
+		sl.Closer = unixCloser{path: spl[1], closer: sl.Closer}
+	}
+
 	return nil
 }
 
@@ -235,6 +253,17 @@ func newSocketListener() *SocketListener {
 	}
 }
 
+type unixCloser struct {
+	path   string
+	closer io.Closer
+}
+
+func (uc unixCloser) Close() error {
+	err := uc.closer.Close()
+	os.Remove(uc.path) // ignore error
+	return err
+}
+
 func init() {
 	inputs.Add("socket_listener", func() telegraf.Input { return newSocketListener() })
 }

plugins/inputs/socket_listener/socket_listener_test.go

@@ -18,6 +18,7 @@ func TestSocketListener_tcp(t *testing.T) {
 	acc := &testutil.Accumulator{}
 	err := sl.Start(acc)
 	require.NoError(t, err)
+	defer sl.Stop()
 
 	client, err := net.Dial("tcp", sl.Closer.(net.Listener).Addr().String())
 	require.NoError(t, err)
@@ -32,6 +33,7 @@ func TestSocketListener_udp(t *testing.T) {
 	acc := &testutil.Accumulator{}
 	err := sl.Start(acc)
 	require.NoError(t, err)
+	defer sl.Stop()
 
 	client, err := net.Dial("udp", sl.Closer.(net.PacketConn).LocalAddr().String())
 	require.NoError(t, err)
@@ -40,13 +42,14 @@ func TestSocketListener_udp(t *testing.T) {
 }
 
 func TestSocketListener_unix(t *testing.T) {
-	defer os.Remove("/tmp/telegraf_test.sock")
+	os.Create("/tmp/telegraf_test.sock")
 	sl := newSocketListener()
 	sl.ServiceAddress = "unix:///tmp/telegraf_test.sock"
 
 	acc := &testutil.Accumulator{}
 	err := sl.Start(acc)
 	require.NoError(t, err)
+	defer sl.Stop()
 
 	client, err := net.Dial("unix", "/tmp/telegraf_test.sock")
 	require.NoError(t, err)
@@ -55,13 +58,14 @@ func TestSocketListener_unix(t *testing.T) {
 }
 
 func TestSocketListener_unixgram(t *testing.T) {
-	defer os.Remove("/tmp/telegraf_test.sock")
+	os.Create("/tmp/telegraf_test.sock")
 	sl := newSocketListener()
 	sl.ServiceAddress = "unixgram:///tmp/telegraf_test.sock"
 
 	acc := &testutil.Accumulator{}
 	err := sl.Start(acc)
 	require.NoError(t, err)
+	defer sl.Stop()
 
 	client, err := net.Dial("unixgram", "/tmp/telegraf_test.sock")
 	require.NoError(t, err)

plugins/outputs/socket_writer/socket_writer_test.go

@@ -44,6 +44,7 @@ func TestSocketWriter_udp(t *testing.T) {
 }
 
 func TestSocketWriter_unix(t *testing.T) {
+	os.Remove("/tmp/telegraf_test.sock")
 	defer os.Remove("/tmp/telegraf_test.sock")
 	listener, err := net.Listen("unix", "/tmp/telegraf_test.sock")
 	require.NoError(t, err)
@@ -61,6 +62,7 @@ func TestSocketWriter_unix(t *testing.T) {
 }
 
 func TestSocketWriter_unixgram(t *testing.T) {
+	os.Remove("/tmp/telegraf_test.sock")
 	defer os.Remove("/tmp/telegraf_test.sock")
 	listener, err := net.ListenPacket("unixgram", "/tmp/telegraf_test.sock")
 	require.NoError(t, err)