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

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

@@ -37,6 +37,7 @@ 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 +105,13 @@ func (g *Graphite) Connect() error {
 
 		// Dialer with timeout
 		d := net.Dialer{Timeout: time.Duration(g.Timeout)}
+		if g.LocalAddr != "" {
+			local, err := net.ResolveIPAddr("tcp", g.LocalAddr)
+			if err != nil {
+				return fmt.Errorf("cannot resolve local address: %w", err)
+			}
+			d.LocalAddr = local
+		}
 
 		// Get secure connection if tls config is set
 		var conn net.Conn

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"