feat(outputs.graphite): Allow to set the local address to bind (#14628)

plugins/outputs/graphite/README.md

@@ -26,8 +26,14 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   ## If multiple endpoints are configured, the output will be load balanced.
   ## Only one of the endpoints will be written to with each iteration.
   servers = ["localhost:2003"]
+
+  ## Local address to bind when connecting to the server
+  ## If empty or not set, the local address is automatically chosen.
+  # local_address = ""
+
   ## Prefix metrics name
   prefix = ""
+
   ## Graphite output template
   ## see https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
   template = "host.tags.measurement.field"

plugins/outputs/graphite/graphite.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"math/rand"
 	"net"
+	"strconv"
 	"strings"
 	"time"
 
@@ -37,6 +38,7 @@ type Graphite struct {
 	GraphiteStrictRegex     string `toml:"graphite_strict_sanitize_regex"`
 	// URL is only for backwards compatibility
 	Servers   []string        `toml:"servers"`
+	LocalAddr string          `toml:"local_address"`
 	Prefix    string          `toml:"prefix"`
 	Template  string          `toml:"template"`
 	Templates []string        `toml:"templates"`
@@ -104,6 +106,28 @@ func (g *Graphite) Connect() error {
 
 		// Dialer with timeout
 		d := net.Dialer{Timeout: time.Duration(g.Timeout)}
+		if g.LocalAddr != "" {
+			// Resolve the local address into IP address and the given port if any
+			addr, sPort, err := net.SplitHostPort(g.LocalAddr)
+			if err != nil && !strings.Contains(err.Error(), "missing port") {
+				return fmt.Errorf("invalid local address: %w", err)
+			}
+			local, err := net.ResolveIPAddr("ip", addr)
+			if err != nil {
+				return fmt.Errorf("cannot resolve local address: %w", err)
+			}
+
+			var port int
+			if sPort != "" {
+				p, err := strconv.ParseUint(sPort, 10, 16)
+				if err != nil {
+					return fmt.Errorf("invalid port: %w", err)
+				}
+				port = int(p)
+			}
+
+			d.LocalAddr = &net.TCPAddr{IP: local.IP, Port: port, Zone: local.Zone}
+		}
 
 		// Get secure connection if tls config is set
 		var conn net.Conn

plugins/outputs/graphite/graphite_test.go

@@ -585,6 +585,23 @@ func TestGraphiteOkWithTagsAndSeparatorUnderscore(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestGraphiteLocalAddress(t *testing.T) {
+	t.Log("Starting server")
+	server, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer server.Close()
+
+	plugin := Graphite{
+		Servers:   []string{server.Addr().String()},
+		LocalAddr: "localhost",
+		Prefix:    "my.prefix",
+		Log:       testutil.Logger{},
+	}
+	require.NoError(t, plugin.Init())
+	require.NoError(t, plugin.Connect())
+	require.NoError(t, plugin.Close())
+}
+
 func TestIntegration(t *testing.T) {
 	if testing.Short() {
 		t.Skip("Skipping integration test in short mode")

plugins/outputs/graphite/sample.conf

@@ -4,8 +4,14 @@
   ## If multiple endpoints are configured, the output will be load balanced.
   ## Only one of the endpoints will be written to with each iteration.
   servers = ["localhost:2003"]
+
+  ## Local address to bind when connecting to the server
+  ## If empty or not set, the local address is automatically chosen.
+  # local_address = ""
+
   ## Prefix metrics name
   prefix = ""
+
   ## Graphite output template
   ## see https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
   template = "host.tags.measurement.field"