Implementing Conditional DNS Forwarding With Resolver Rules

Introduction

In this guide, we will implement conditional DNS forwarding using AWS Route 53 Resolver rules with Pulumi. AWS Route 53 Resolver rules allow you to configure DNS resolution for your VPCs, enabling conditional forwarding to other DNS servers based on domain names.

Step-by-Step Explanation

Step 1: Set Up Your Pulumi Project

1. Initialize a new Pulumi project if you haven’t already:

   pulumi new aws-typescript
   

2. Install the necessary Pulumi packages:

   npm install @pulumi/aws
   

Step 2: Create a VPC

1. Define a new VPC:

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

Step 3: Create Subnets

1. Create subnets within the VPC:

   const subnet = new aws.ec2.Subnet("my-subnet", {
       vpcId: vpc.id,
       cidrBlock: "10.0.1.0/24",
       availabilityZone: "us-west-2a",
   });
   

Step 4: Create a Route 53 Resolver Rule

1. Define the resolver rule for conditional forwarding:

   const resolverRule = new aws.route53.ResolverRule("my-resolver-rule", {
       domainName: "example.com",
       ruleType: "FORWARD",
       targetIps: [{
           ip: "8.8.8.8",
           port: 53,
       }],
       resolverEndpointId: resolverEndpoint.id,
   });
   

Step 5: Create a Resolver Endpoint

1. Define the resolver endpoint:

   const resolverEndpoint = new aws.route53.ResolverEndpoint("my-resolver-endpoint", {
       direction: "OUTBOUND",
       ipAddresses: [{
           subnetId: subnet.id,
       }],
       securityGroupIds: [securityGroup.id],
   });
   

Step 6: Create a Security Group

1. Define a security group for the resolver endpoint:

   const securityGroup = new aws.ec2.SecurityGroup("my-security-group", {
       vpcId: vpc.id,
       ingress: [{
           protocol: "udp",
           fromPort: 53,
           toPort: 53,
           cidrBlocks: ["0.0.0.0/0"],
       }],
       egress: [{
           protocol: "-1",
           fromPort: 0,
           toPort: 0,
           cidrBlocks: ["0.0.0.0/0"],
       }],
   });
   

Summary

In this guide, we implemented conditional DNS forwarding using AWS Route 53 Resolver rules with Pulumi. We created a VPC, subnets, a security group, a resolver endpoint, and a resolver rule to forward DNS queries for a specific domain to an external DNS server. This setup allows you to manage DNS resolution for your VPCs effectively.

For more details, refer to the Pulumi AWS documentation.

Full Code Example

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,
});

// Create a subnet within the VPC
const subnet = new aws.ec2.Subnet("my-subnet", {
    vpcId: vpc.id,
    cidrBlock: "10.0.1.0/24",
    availabilityZone: "us-west-2a",
});

// Create a security group for the resolver endpoint
const securityGroup = new aws.ec2.SecurityGroup("my-security-group", {
    vpcId: vpc.id,
    ingress: [{
        protocol: "udp",
        fromPort: 53,
        toPort: 53,
        cidrBlocks: ["0.0.0.0/0"],
    }],
    egress: [{
        protocol: "-1",
        fromPort: 0,
        toPort: 0,
        cidrBlocks: ["0.0.0.0/0"],
    }],
});

// Create a resolver endpoint
const resolverEndpoint = new aws.route53.ResolverEndpoint("my-resolver-endpoint", {
    direction: "OUTBOUND",
    ipAddresses: [{
        subnetId: subnet.id,
    }],
    securityGroupIds: [securityGroup.id],
});

// Create a resolver rule for conditional forwarding
const resolverRule = new aws.route53.ResolverRule("my-resolver-rule", {
    domainName: "example.com",
    ruleType: "FORWARD",
    targetIps: [{
        ip: "8.8.8.8",
        port: 53,
    }],
    resolverEndpointId: resolverEndpoint.id,
});