Lambda(golang)でFargate Spotの終了通知を受けたECSのタスクをNLBから切り離す

type NetworkInterface struct {
	PrivateIpv4Address string `json:"privateIpv4Address"`
}
type Container struct {
	NetworkInterfaces []NetworkInterface
	Name              string `json:"name"`
}
type EcsEvent struct {
	StopCode   string `json:"stopCode"`
	Containers []Container
}

func HandleLambdaEvent(_ context.Context, event events.CloudWatchEvent) {
	// 1. Event Bridgeからイベントを受け取る
	var ecsEvent EcsEvent
	if err := json.Unmarshal(event.Detail, &ecsEvent); err != nil {
		os.Exit(1)
	}
	// 2. 終了通知かチェック
	fmt.Printf("stopCode = %s\n", ecsEvent.StopCode)
	if ecsEvent.StopCode != "TerminationNotice" {
		return
	}
	// 3. 対象タスクのIP取得
	var ecsIp string
	for _, contaier := range ecsEvent.Containers {
		if contaier.Name == "logstash" {
			for _, ni := range contaier.NetworkInterfaces {
				ecsIp = ni.PrivateIpv4Address
			}
		}
	}
	fmt.Printf("ip v4 = %s\n", ecsIp)
	// 4. 環境変数取得
	nlbId := os.Getenv("NlbId")
	nlbTargetGroupId := os.Getenv("NlbTargetGroupId")
	fmt.Printf("GET ENV AlbId: %s AlbTargetGroupId: %s\n", nlbId, nlbTargetGroupId)
	// 5. 初期設定
	svc := Init()
	// 6. 指定したLoadbalancerを取得
	lb := GetSpecifiedLoadbalancer(svc, nlbId)
	fmt.Printf("GET LoadbalancerName: %s LoadbalancerArn: %s\n", *lb.LoadBalancerName, *lb.LoadBalancerArn)
	// 7. 指定したLoadbalancerのTargetGroupを取得
	tg := GetSpecifiedTargetGroup(svc, lb, nlbTargetGroupId)
	fmt.Printf("GET TargetGroupName: %s TargetGroupArn: %s\n", *tg.TargetGroupName, *tg.TargetGroupArn)
	// 8. TargetGroupからTargetの登録を解除
	if HasTarget(svc, tg, ecsIp) {
		const tcpPort = 5044
		DeregisterSpecifiedTarget(svc, tg, ecsIp, tcpPort)
		fmt.Println("DEREGISTER")
	}
}