Code to Get VPCs, Subnets by CIDR, and NAT

In this solution, we will use Pulumi to create and manage AWS infrastructure, including VPCs, subnets, and NAT gateways. Pulumi is an Infrastructure as Code (IaC) tool that allows you to define and deploy cloud resources using familiar programming languages. The key services involved in this solution are Amazon VPC, Amazon Subnets, and Amazon NAT Gateway.

Step-by-Step Explanation

Step 1: Create a VPC

We will start by creating a new VPC with a specified CIDR block.

Step 2: Create Subnets

Next, we will create public and private subnets within the VPC, each with its own CIDR block.

Step 3: Create an Internet Gateway

We will create an Internet Gateway and attach it to the VPC to allow internet access for the public subnets.

Step 4: Create a NAT Gateway

We will create a NAT Gateway in one of the public subnets to enable internet access for instances in the private subnets.

Step 5: Create Route Tables

We will create route tables for the public and private subnets and associate them with the respective subnets.

Key Points

• Pulumi allows you to define cloud infrastructure using familiar programming languages.
• Amazon VPC provides a logically isolated network in the AWS cloud.
• Subnets allow you to partition the VPC’s IP address range into smaller segments.
• NAT Gateway enables instances in private subnets to access the internet while remaining private.

Conclusion

In this solution, we demonstrated how to use Pulumi to create and manage AWS infrastructure, including VPCs, subnets, and NAT gateways. By using Pulumi, you can define your cloud resources using code, making it easier to version, share, and manage your infrastructure.

Full Code Example

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

// Create a VPC
const vpc = new aws.ec2.Vpc("my-vpc", {
    cidrBlock: "10.0.0.0/16",
    enableDnsSupport: true,
    enableDnsHostnames: true,
    tags: { Name: "my-vpc" },
});

// Create a public subnet
const publicSubnet = new aws.ec2.Subnet("public-subnet", {
    vpcId: vpc.id,
    cidrBlock: "10.0.1.0/24",
    mapPublicIpOnLaunch: true,
    availabilityZone: "us-west-2a",
    tags: { Name: "public-subnet" },
});

// Create a private subnet
const privateSubnet = new aws.ec2.Subnet("private-subnet", {
    vpcId: vpc.id,
    cidrBlock: "10.0.2.0/24",
    availabilityZone: "us-west-2a",
    tags: { Name: "private-subnet" },
});

// Create an Internet Gateway
const internetGateway = new aws.ec2.InternetGateway("internet-gateway", {
    vpcId: vpc.id,
    tags: { Name: "internet-gateway" },
});

// Create a NAT Gateway
const eip = new aws.ec2.Eip("nat-eip", { vpc: true });
const natGateway = new aws.ec2.NatGateway("nat-gateway", {
    subnetId: publicSubnet.id,
    allocationId: eip.id,
    tags: { Name: "nat-gateway" },
});

// Create a route table for the public subnet
const publicRouteTable = new aws.ec2.RouteTable("public-route-table", {
    vpcId: vpc.id,
    routes: [{
        cidrBlock: "0.0.0.0/0",
        gatewayId: internetGateway.id,
    }],
    tags: { Name: "public-route-table" },
});

// Associate the public subnet with the public route table
new aws.ec2.RouteTableAssociation("public-route-table-association", {
    subnetId: publicSubnet.id,
    routeTableId: publicRouteTable.id,
});

// Create a route table for the private subnet
const privateRouteTable = new aws.ec2.RouteTable("private-route-table", {
    vpcId: vpc.id,
    routes: [{
        cidrBlock: "0.0.0.0/0",
        natGatewayId: natGateway.id,
    }],
    tags: { Name: "private-route-table" },
});

// Associate the private subnet with the private route table
new aws.ec2.RouteTableAssociation("private-route-table-association", {
    subnetId: privateSubnet.id,
    routeTableId: privateRouteTable.id,
});

export const vpcId = vpc.id;
export const publicSubnetId = publicSubnet.id;
export const privateSubnetId = privateSubnet.id;
export const natGatewayId = natGateway.id;
export const internetGatewayId = internetGateway.id;
export const routeTableId = publicRouteTable.id;