// NAT instance
        const natInstance = new ec2.Instance(this, "nat-instance", {
            vpc,
            vpcSubnets: { subnetType: ec2.SubnetType.PUBLIC },
            instanceType: new ec2.InstanceType("t3.micro"),
            machineImage: new ec2.NatInstanceImage(),
            securityGroup: natSG,
            // Helps SSH into the instance
            // You need to create a key pair in AWS console and download the .pem file in named seungho-key-pair.pem
            keyName: "seungho-key-pair",
            // Need this for NAT instance
            sourceDestCheck: false,
        });
        // Attach Elastic IP to NAT instance
        const eIPAssociation = new ec2.CfnEIPAssociation(
            this,
            "Nat EIP Association",
            {
                instanceId: natInstance.instanceId,
                eip: new ec2.CfnEIP(this, "Nat EIP", {}).ref,
            }
        );
        // Update Private Subnet Route Table
        vpc.privateSubnets.forEach((subnet, index) => {
            const route = new ec2.CfnRoute(this, `NAT ROUTE${index + 1}`, {
                routeTableId: subnet.routeTable.routeTableId,
                destinationCidrBlock: "0.0.0.0/0",
                instanceId: natInstance.instanceId,
            });
            // Make sure NAT instance is created before creating route
            route.addDependsOn(natInstance.instance);
            route.addDependsOn(eIPAssociation);
        });