feat(outputs.influxdb): Add option to define local address (#15225)

plugins/outputs/influxdb/README.md

@@ -34,6 +34,10 @@ to use them.
   # urls = ["udp://127.0.0.1:8089"]
   # urls = ["http://127.0.0.1:8086"]
 
+  ## Local address to bind when connecting to the server
+  ## If empty or not set, the local address is automatically chosen.
+  # local_address = ""
+
   ## The target database for metrics; will be created as needed.
   ## For UDP url endpoint database needs to be configured on server side.
   # database = "telegraf"

plugins/outputs/influxdb/http.go

@@ -87,6 +87,7 @@ func (r WriteResponseError) Error() string {
 
 type HTTPConfig struct {
 	URL                       *url.URL
+	LocalAddr                 *net.TCPAddr
 	UserAgent                 string
 	Timeout                   time.Duration
 	Username                  config.Secret
@@ -164,9 +165,15 @@ func NewHTTPClient(cfg HTTPConfig) (*httpClient, error) {
 	var transport *http.Transport
 	switch cfg.URL.Scheme {
 	case "http", "https":
+		var dialerFunc func(ctx context.Context, network, addr string) (net.Conn, error)
+		if cfg.LocalAddr != nil {
+			dialer := &net.Dialer{LocalAddr: cfg.LocalAddr}
+			dialerFunc = dialer.DialContext
+		}
 		transport = &http.Transport{
 			Proxy:           proxy,
 			TLSClientConfig: cfg.TLSConfig,
+			DialContext:     dialerFunc,
 		}
 	case "unix":
 		transport = &http.Transport{

plugins/outputs/influxdb/influxdb.go

@@ -7,7 +7,10 @@ import (
 	"errors"
 	"fmt"
 	"math/rand"
+	"net"
 	"net/url"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/influxdata/telegraf"
@@ -37,6 +40,7 @@ type Client interface {
 // InfluxDB struct is the primary data structure for the plugin
 type InfluxDB struct {
 	URLs                      []string          `toml:"urls"`
+	LocalAddr                 string            `toml:"local_address"`
 	Username                  config.Secret     `toml:"username"`
 	Password                  config.Secret     `toml:"password"`
 	Database                  string            `toml:"database"`
@@ -89,16 +93,54 @@ func (i *InfluxDB) Connect() error {
 			}
 		}
 
+		var localIP *net.IPAddr
+		var localPort int
+		if i.LocalAddr != "" {
+			var err error
+			// Resolve the local address into IP address and the given port if any
+			addr, sPort, err := net.SplitHostPort(i.LocalAddr)
+			if err != nil {
+				if !strings.Contains(err.Error(), "missing port") {
+					return fmt.Errorf("invalid local address: %w", err)
+				}
+				addr = i.LocalAddr
+			}
+			localIP, err = net.ResolveIPAddr("ip", addr)
+			if err != nil {
+				return fmt.Errorf("cannot resolve local address: %w", err)
+			}
+
+			if sPort != "" {
+				p, err := strconv.ParseUint(sPort, 10, 16)
+				if err != nil {
+					return fmt.Errorf("invalid port: %w", err)
+				}
+				localPort = int(p)
+			}
+		}
+
 		switch parts.Scheme {
 		case "udp", "udp4", "udp6":
-			c, err := i.udpClient(parts)
+			var c Client
+			var err error
+			if i.LocalAddr == "" {
+				c, err = i.udpClient(parts, nil)
+			} else {
+				c, err = i.udpClient(parts, &net.UDPAddr{IP: localIP.IP, Port: localPort, Zone: localIP.Zone})
+			}
 			if err != nil {
 				return err
 			}
 
 			i.clients = append(i.clients, c)
 		case "http", "https", "unix":
-			c, err := i.httpClient(ctx, parts, proxy)
+			var c Client
+			var err error
+			if i.LocalAddr == "" {
+				c, err = i.httpClient(ctx, parts, nil, proxy)
+			} else {
+				c, err = i.httpClient(ctx, parts, &net.TCPAddr{IP: localIP.IP, Port: localPort, Zone: localIP.Zone}, proxy)
+			}
 			if err != nil {
 				return err
 			}
@@ -159,7 +201,7 @@ func (i *InfluxDB) Write(metrics []telegraf.Metric) error {
 	return errors.New("could not write any address")
 }
 
-func (i *InfluxDB) udpClient(address *url.URL) (Client, error) {
+func (i *InfluxDB) udpClient(address *url.URL, localAddr *net.UDPAddr) (Client, error) {
 	serializer := &influx.Serializer{UintSupport: i.InfluxUintSupport}
 	if err := serializer.Init(); err != nil {
 		return nil, err
@@ -167,6 +209,7 @@ func (i *InfluxDB) udpClient(address *url.URL) (Client, error) {
 
 	udpConfig := &UDPConfig{
 		URL:            address,
+		LocalAddr:      localAddr,
 		MaxPayloadSize: int(i.UDPPayload),
 		Serializer:     serializer,
 		Log:            i.Log,
@@ -180,7 +223,7 @@ func (i *InfluxDB) udpClient(address *url.URL) (Client, error) {
 	return c, nil
 }
 
-func (i *InfluxDB) httpClient(ctx context.Context, address *url.URL, proxy *url.URL) (Client, error) {
+func (i *InfluxDB) httpClient(ctx context.Context, address *url.URL, localAddr *net.TCPAddr, proxy *url.URL) (Client, error) {
 	tlsConfig, err := i.ClientConfig.TLSConfig()
 	if err != nil {
 		return nil, err
@@ -193,6 +236,7 @@ func (i *InfluxDB) httpClient(ctx context.Context, address *url.URL, proxy *url.
 
 	httpConfig := &HTTPConfig{
 		URL:                       address,
+		LocalAddr:                 localAddr,
 		Timeout:                   time.Duration(i.Timeout),
 		TLSConfig:                 tlsConfig,
 		UserAgent:                 i.UserAgent,

plugins/outputs/influxdb/influxdb_test.go

@@ -214,3 +214,23 @@ func TestWriteRecreateDatabaseIfDatabaseNotFound(t *testing.T) {
 	// We only have one URL, so we expect an error
 	require.Error(t, err)
 }
+
+func TestInfluxDBLocalAddress(t *testing.T) {
+	output := influxdb.InfluxDB{
+		URLs:      []string{"http://localhost:8086"},
+		LocalAddr: "localhost",
+
+		CreateHTTPClientF: func(_ *influxdb.HTTPConfig) (influxdb.Client, error) {
+			return &MockClient{
+				DatabaseF: func() string {
+					return "telegraf"
+				},
+				CreateDatabaseF: func() error {
+					return nil
+				},
+			}, nil
+		},
+	}
+
+	require.NoError(t, output.Connect())
+}

plugins/outputs/influxdb/sample.conf

@@ -8,6 +8,10 @@
   # urls = ["udp://127.0.0.1:8089"]
   # urls = ["http://127.0.0.1:8086"]
 
+  ## Local address to bind when connecting to the server
+  ## If empty or not set, the local address is automatically chosen.
+  # local_address = ""
+
   ## The target database for metrics; will be created as needed.
   ## For UDP url endpoint database needs to be configured on server side.
   # database = "telegraf"

plugins/outputs/influxdb/udp.go

@@ -29,6 +29,7 @@ type Conn interface {
 type UDPConfig struct {
 	MaxPayloadSize int
 	URL            *url.URL
+	LocalAddr      *net.UDPAddr
 	Serializer     *influx.Serializer
 	Dialer         Dialer
 	Log            telegraf.Logger
@@ -55,7 +56,7 @@ func NewUDPClient(config UDPConfig) (*udpClient, error) {
 
 	dialer := config.Dialer
 	if dialer == nil {
-		dialer = &netDialer{net.Dialer{}}
+		dialer = &netDialer{net.Dialer{LocalAddr: config.LocalAddr}}
 	}
 
 	client := &udpClient{