EC2 + RDS マルチAZ冗長構成

import * as cdk from "aws-cdk-lib";
import { Construct } from "constructs";
import * as ec2 from "aws-cdk-lib/aws-ec2";
import * as autoscaling from "aws-cdk-lib/aws-autoscaling";
import * as elbv2 from "aws-cdk-lib/aws-elasticloadbalancingv2";
import * as rds from "aws-cdk-lib/aws-rds";

export class WebMultiAzStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const vpc = new ec2.Vpc(this, "Vpc", {
      maxAzs: 2,
      natGateways: 1,
    });

    const asg = new autoscaling.AutoScalingGroup(this, "WebAsg", {
      vpc,
      instanceType: new ec2.InstanceType("t3.small"),
      machineImage: ec2.MachineImage.latestAmazonLinux2023(),
      minCapacity: 2,
      maxCapacity: 4,
      desiredCapacity: 2,
      vpcSubnets: { subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS },
    });

    const alb = new elbv2.ApplicationLoadBalancer(this, "Alb", {
      vpc,
      internetFacing: true,
    });

    const listener = alb.addListener("Http", { port: 80, open: true });
    listener.addTargets("WebFleet", {
      port: 80,
      targets: [asg],
      healthCheck: { path: "/" },
    });

    new rds.DatabaseInstance(this, "AppDb", {
      vpc,
      engine: rds.DatabaseInstanceEngine.postgres({
        version: rds.PostgresEngineVersion.VER_16,
      }),
      multiAz: true,
      allocatedStorage: 100,
      storageEncrypted: true,
      instanceType: ec2.InstanceType.of(ec2.InstanceClass.T3, ec2.InstanceSize.MEDIUM),
      vpcSubnets: { subnetType: ec2.SubnetType.PRIVATE_ISOLATED },
      publiclyAccessible: false,
      removalPolicy: cdk.RemovalPolicy.RETAIN,
    });
  }
}