AWS CDKで全Lambda関数の実行時間アラームを一括設定する

import { aws_lambda as lambda, Duration } from "aws-cdk-lib";
import { Construct } from "constructs";

export class Lambda extends Construct {
  public readonly functions: lambda.Function[] = [];

  constructor(scope: Construct, id: string) {
    super(scope, id);

    new lambda.Function(this, "CwDurationAlertLambda1", {
      runtime: lambda.Runtime.PYTHON_3_10,
      handler: "index.handler",
      timeout: Duration.seconds(120),
      code: lambda.Code.fromAsset("src"),
    });

    new lambda.Function(this, "CwDurationAlertLambda2", {
      runtime: lambda.Runtime.PYTHON_3_10,
      handler: "index.handler",
      timeout: Duration.seconds(180),
      code: lambda.Code.fromAsset("src"),
    });

    new lambda.Function(this, "CwDurationAlertLambda3", {
      runtime: lambda.Runtime.PYTHON_3_10,
      handler: "index.handler",
      timeout: Duration.seconds(240),
      code: lambda.Code.fromAsset("src"),
    });

    // すべてのLambda関数を取得
    const lambdaFunctions = this.node
      .findAll()
      .filter(
        (child): child is lambda.Function => child instanceof lambda.Function
      );
    this.functions = lambdaFunctions;
  }
}

import {
  aws_cloudwatch as cloudwatch,
  aws_lambda as lambda,
} from "aws-cdk-lib";
import { Construct } from "constructs";

export class CloudWatch extends Construct {
  constructor(
    scope: Construct,
    id: string,
    lambdaFunctions: lambda.Function[]
  ) {
    super(scope, id);
    // 各Lambda関数に対してアラームを作成
    lambdaFunctions.forEach((lambdaFunction) => {
      this.createDurationAlarm(lambdaFunction);
    });
  }
  private createDurationAlarm(lambdaFunction: lambda.Function) {
    const timeout = lambdaFunction.timeout?.toSeconds() ?? 3;
    const alarmThreshold = timeout * 0.8;

    new cloudwatch.Alarm(this, `${lambdaFunction.node.id}DurationAlarm`, {
      metric: lambdaFunction.metricDuration(),
      threshold: alarmThreshold,
      evaluationPeriods: 1,
      alarmDescription: `Alarm when ${lambdaFunction.node.id} duration exceeds ${alarmThreshold} seconds`,
      comparisonOperator: cloudwatch.ComparisonOperator.GREATER_THAN_THRESHOLD,
      treatMissingData: cloudwatch.TreatMissingData.NOT_BREACHING,
    });
  }
}

import json
import time

def handler(event, context):
    time.sleep(110)
    return {"statusCode": 200, "body": json.dumps("Hello from Lambda!")}