Add ContentEncoder to socket_writer for datagram sockets (#7417)

plugins/outputs/socket_writer/README.md

@@ -32,6 +32,11 @@ It can output data in any of the [supported output formats](https://github.com/i
   ## Defaults to the OS configuration.
   # keep_alive_period = "5m"
 
+  ## Content encoding for message payloads, can be set to "gzip" or to
+  ## "identity" to apply no encoding.
+  ##
+  # content_encoding = "identity"
+
   ## Data format to generate.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:

plugins/outputs/socket_writer/socket_writer.go

@@ -15,12 +15,15 @@ import (
 )
 
 type SocketWriter struct {
+	ContentEncoding string `toml:"content_encoding"`
 	Address         string
 	KeepAlivePeriod *internal.Duration
 	tlsint.ClientConfig
 
 	serializers.Serializer
 
+	encoder internal.ContentEncoder
+
 	net.Conn
 }
 
@@ -55,6 +58,11 @@ func (sw *SocketWriter) SampleConfig() string {
   ## Defaults to the OS configuration.
   # keep_alive_period = "5m"
 
+  ## Content encoding for packet-based connections (i.e. UDP, unixgram).
+  ## Can be set to "gzip" or to "identity" to apply no encoding.
+  ##
+  # content_encoding = "identity"
+
   ## Data format to generate.
   ## Each data format has its own unique set of configuration options, read
   ## more about them here:
@@ -91,6 +99,11 @@ func (sw *SocketWriter) Connect() error {
 	if err := sw.setKeepAlive(c); err != nil {
 		log.Printf("unable to configure keep alive (%s): %s", sw.Address, err)
 	}
+	//set encoder
+	sw.encoder, err = internal.NewContentEncoder(sw.ContentEncoding)
+	if err != nil {
+		return err
+	}
 
 	sw.Conn = c
 	return nil
@@ -130,6 +143,13 @@ func (sw *SocketWriter) Write(metrics []telegraf.Metric) error {
 			log.Printf("D! [outputs.socket_writer] Could not serialize metric: %v", err)
 			continue
 		}
+
+		bs, err = sw.encoder.Encode(bs)
+		if err != nil {
+			log.Printf("D! [outputs.socket_writer] Could not encode metric: %v", err)
+			continue
+		}
+
 		if _, err := sw.Conn.Write(bs); err != nil {
 			//TODO log & keep going with remaining strings
 			if err, ok := err.(net.Error); !ok || !err.Temporary() {

plugins/outputs/socket_writer/socket_writer_test.go

@@ -2,7 +2,6 @@ package socket_writer
 
 import (
 	"bufio"
-	"bytes"
 	"io/ioutil"
 	"net"
 	"os"
@@ -88,8 +87,10 @@ func testSocketWriter_stream(t *testing.T, sw *SocketWriter, lconn net.Conn) {
 	metrics := []telegraf.Metric{}
 	metrics = append(metrics, testutil.TestMetric(1, "test"))
 	mbs1out, _ := sw.Serialize(metrics[0])
+	mbs1out, _ = sw.encoder.Encode(mbs1out)
 	metrics = append(metrics, testutil.TestMetric(2, "test"))
 	mbs2out, _ := sw.Serialize(metrics[1])
+	mbs2out, _ = sw.encoder.Encode(mbs2out)
 
 	err := sw.Write(metrics)
 	require.NoError(t, err)
@@ -108,8 +109,12 @@ func testSocketWriter_packet(t *testing.T, sw *SocketWriter, lconn net.PacketCon
 	metrics := []telegraf.Metric{}
 	metrics = append(metrics, testutil.TestMetric(1, "test"))
 	mbs1out, _ := sw.Serialize(metrics[0])
+	mbs1out, _ = sw.encoder.Encode(mbs1out)
+	mbs1str := string(mbs1out)
 	metrics = append(metrics, testutil.TestMetric(2, "test"))
 	mbs2out, _ := sw.Serialize(metrics[1])
+	mbs2out, _ = sw.encoder.Encode(mbs2out)
+	mbs2str := string(mbs2out)
 
 	err := sw.Write(metrics)
 	require.NoError(t, err)
@@ -119,17 +124,12 @@ func testSocketWriter_packet(t *testing.T, sw *SocketWriter, lconn net.PacketCon
 	for len(mstrins) < 2 {
 		n, _, err := lconn.ReadFrom(buf)
 		require.NoError(t, err)
-		for _, bs := range bytes.Split(buf[:n], []byte{'\n'}) {
-			if len(bs) == 0 {
-				continue
-			}
-			mstrins = append(mstrins, string(bs)+"\n")
-		}
+		mstrins = append(mstrins, string(buf[:n]))
 	}
 	require.Len(t, mstrins, 2)
 
-	assert.Equal(t, string(mbs1out), mstrins[0])
-	assert.Equal(t, string(mbs2out), mstrins[1])
+	assert.Equal(t, mbs1str, mstrins[0])
+	assert.Equal(t, mbs2str, mstrins[1])
 }
 
 func TestSocketWriter_Write_err(t *testing.T) {
@@ -195,3 +195,17 @@ func TestSocketWriter_Write_reconnect(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, string(mbsout), string(buf[:n]))
 }
+
+func TestSocketWriter_udp_gzip(t *testing.T) {
+	listener, err := net.ListenPacket("udp", "127.0.0.1:0")
+	require.NoError(t, err)
+
+	sw := newSocketWriter()
+	sw.Address = "udp://" + listener.LocalAddr().String()
+	sw.ContentEncoding = "gzip"
+
+	err = sw.Connect()
+	require.NoError(t, err)
+
+	testSocketWriter_packet(t, sw, listener)
+}