feat(outputs.influxdb_v2): Add option to set local address

plugins/outputs/influxdb_v2/README.md

@@ -31,6 +31,10 @@ to use them.
   ##   ex: urls = ["https://us-west-2-1.aws.cloud2.influxdata.com"]
   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 = ""
+
   ## Token for authentication.
   token = ""
 

plugins/outputs/influxdb_v2/http.go

@@ -44,6 +44,7 @@ const (
 
 type HTTPConfig struct {
 	URL              *url.URL
+	LocalAddr        *net.TCPAddr
 	Token            config.Secret
 	Organization     string
 	Bucket           string
@@ -125,9 +126,15 @@ 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,
 		}
 		if cfg.ReadIdleTimeout != 0 || cfg.PingTimeout != 0 {
 			http2Trans, err := http2.ConfigureTransports(transport)

plugins/outputs/influxdb_v2/influxdb_v2.go

@@ -7,7 +7,10 @@ import (
 	"errors"
 	"fmt"
 	"math/rand"
+	"net"
 	"net/url"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/influxdata/telegraf"
@@ -35,6 +38,7 @@ type Client interface {
 
 type InfluxDB struct {
 	URLs             []string          `toml:"urls"`
+	LocalAddr        string            `toml:"local_address"`
 	Token            config.Secret     `toml:"token"`
 	Organization     string            `toml:"organization"`
 	Bucket           string            `toml:"bucket"`
@@ -78,9 +82,36 @@ func (i *InfluxDB) Connect() error {
 			}
 		}
 
+		var localAddr *net.TCPAddr
+		if i.LocalAddr != "" {
+			// 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
+			}
+			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)
+			}
+
+			localAddr = &net.TCPAddr{IP: local.IP, Port: port, Zone: local.Zone}
+		}
+
 		switch parts.Scheme {
 		case "http", "https", "unix":
-			c, err := i.getHTTPClient(parts, proxy)
+			c, err := i.getHTTPClient(parts, localAddr, proxy)
 			if err != nil {
 				return err
 			}
@@ -121,7 +152,7 @@ func (i *InfluxDB) Write(metrics []telegraf.Metric) error {
 	return errors.New("failed to send metrics to any configured server(s)")
 }
 
-func (i *InfluxDB) getHTTPClient(address *url.URL, proxy *url.URL) (Client, error) {
+func (i *InfluxDB) getHTTPClient(address *url.URL, localAddr *net.TCPAddr, proxy *url.URL) (Client, error) {
 	tlsConfig, err := i.ClientConfig.TLSConfig()
 	if err != nil {
 		return nil, err
@@ -134,6 +165,7 @@ func (i *InfluxDB) getHTTPClient(address *url.URL, proxy *url.URL) (Client, erro
 
 	httpConfig := &HTTPConfig{
 		URL:              address,
+		LocalAddr:        localAddr,
 		Token:            i.Token,
 		Organization:     i.Organization,
 		Bucket:           i.Bucket,

plugins/outputs/influxdb_v2/influxdb_v2_test.go

@@ -1,6 +1,7 @@
 package influxdb_v2_test
 
 import (
+	"net"
 	"testing"
 
 	"github.com/influxdata/telegraf/plugins/common/tls"
@@ -100,3 +101,14 @@ func TestUnused(_ *testing.T) {
 	thing.SampleConfig()
 	outputs.Outputs["influxdb_v2"]()
 }
+
+func TestInfluxDBLocalAddress(t *testing.T) {
+	t.Log("Starting server")
+	server, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer server.Close()
+
+	output := influxdb.InfluxDB{LocalAddr: "localhost"}
+	require.NoError(t, output.Connect())
+	require.NoError(t, output.Close())
+}

plugins/outputs/influxdb_v2/sample.conf

@@ -7,6 +7,10 @@
   ##   ex: urls = ["https://us-west-2-1.aws.cloud2.influxdata.com"]
   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 = ""
+
   ## Token for authentication.
   token = ""