// SQS, SNS の用意
    this.sns_topic = new Topic(
      this, "crypto-notifier-sns"
    )

    this.deadLetterQueue = new Queue(this, 'deadLetterQueue');

   // notifyLambdaにsnsに関する権限を付与
    const snsTopicPolicy = new PolicyStatement({
      actions: ['sns:*'],
      resources: ['*'],
    });

   // Slack通知用Lambda
    this.slackNotifyLambda = new NodejsFunction(this, 'slack-notify-lambda', {
      entry: path.join(__dirname, '../lambda-fns/slack-notifier.js'),
      functionName: 'slack-notifier',
      handler: 'handler',
      runtime: Runtime.NODEJS_16_X,
      bundling: {
        nodeModules: ['phin']
      },
      environment: {
        HOOK_URL: slack_webhook,
      },
    });

    this.slackNotifyLambda.addEventSource(new SnsEventSource(
      this.sns_topic, {
        deadLetterQueue: this.deadLetterQueue
    })
    )