Posted on by Javier Aguilar

Redirect WWW Url to Apex Domain

One of the most common configurations to put in place when we have our website accessible from the internet is redirecting the www URL to an apex domain.

This allows our website to keep its identity and make our brand much more recognizable.

The following diagram represents a typical scenario where we have a Web Server installed in an EC2 instance behind a Load Balancer that redirects the traffic to our server and we will use an S3 Bucket together with Cloudfront to perform the domain redirection.

Repository

As usual, you can find all the Cloudformation templates used to build this example in the GodOfCloud GitHub repository. For this example, the repository only contains a folder with the Cloudformation templates to create the AWS resources.

Requirements

For this example, we have a few requirements that we need to configure before creating all the resources.

  1. A VPC with at least two public subnets and one private subnet.
  2. A NatGateway configured in the public subnet because our EC2 will need to have access to the internet to install the Apache server.
  3. A valid domain in Route 53
  4. A valid certificate for our domain created in the region where the stack is going to be created, this certificate will be attached to the Application Load Balancer (Only required if we want to configure HTTPS)
  5. A valid certificate for our domain and *.domain created in the region us-east-1. This certificate will be attached to Cloudfront.
  6. Copy the template folder from the GitHub repository into an S3 Bucket to be referenced from Cloudformation.

Parameters

prefix:
   Type: String
   Default: www-redirect-apex
resourcesBucket:
   Type: String
vpcId:
   Type: AWS::EC2::VPC::Id
albSubnets:
   Type: List
ec2Subnet:
   Type: AWS::EC2::Subnet::Id
enableHTTPS:
   Type: String
   Default: true
   AllowedValues: [true, false]
albCertificateARN:
   Type: String
cfCertificateARN:
   Type: String
domain:
   Type: String

The master template has a few parameters that we need to define to configure properly the resources that we are about to create.

  • prefix: Prefix name for the resources.
  • resourcesBucket: Bucket where all the templates are stored
  • vpcId: VPC Id.
  • albSubnets: Public subnets where the ALB will be attached (at least two in different availablity zones).
  • ec2Subnet: Private subnet where the EC2 Instance will be created.
  • enableHTTPS: Flag to enable HTTPS connection (By default is true).
  • albCertificateARN: Certificate ARN that will be attached to the Application Load Balancer.
  • cfCertificateARN: Certificate ARN that will be attached to Cloudfront.
  • domain: Custom domain, for instance, example.com

Solution

To perform the redirection from a domain with www to an apex domain there are three key resources that we need to create

S3 Stack

This stack creates the S3 Bucket that we are going to use to redirect the request from the www domain to the apex domain.

Basically, we configure the S3 Bucket as a Static Website Hosting, with the option of redirecting all the requests to another domain.

Is a good practice to name your Bucket with the full domain name, for example www.example.com, but it’s not really necessary in case the full name is not available.

WWWBucket:
   Type: AWS::S3::Bucket
   Properties:
      BucketName: !Sub 'www.${domain}'
      WebsiteConfiguration:
         RedirectAllRequestsTo:
            HostName: !Ref domain
            Protocol: !If [ EnableHTTPS, https, HTTP ]
      PublicAccessBlockConfiguration:
         BlockPublicAcls: true
         BlockPublicPolicy: true
         IgnorePublicAcls: true
         RestrictPublicBuckets: true

Cloudfront Stack

We will configure a Cloudfront distribution to use as origin the S3 Bucket that we’ve created earlier to performs the redirection to our apex domain.

The distribution should have attached a certificate that has the www qualified domain name specified, for instance, www.example.com or a wildcard domain such as *.example.com and define the www.example.com as CNAME.

WWWCloudfront:
   Type: AWS::CloudFront::Distribution
   Properties:
     DistributionConfig:
       Comment: Cloudfront distribution for WWW Domain
       Aliases: 
         - !Sub 'www.${domain}'
       Origins:
         - Id: WWWOrigin
           DomainName: !Sub '${wwwBucket}.s3-website.${AWS::Region}.amazonaws.com'
           CustomOriginConfig:
             OriginProtocolPolicy: http-only
       Enabled: true
       HttpVersion: 'http2'
       PriceClass: PriceClass_All
       DefaultCacheBehavior:
         AllowedMethods:
         - GET
         - HEAD
         - OPTIONS
         Compress: true
         TargetOriginId: WWWOrigin
         ForwardedValues:
           QueryString: false
           Cookies:
             Forward: none
         ViewerProtocolPolicy: allow-all
       ViewerCertificate:
         AcmCertificateArn: !Ref cfCertificateARN
         SslSupportMethod: sni-only
         MinimumProtocolVersion: TLSv1.1_2016

DNS Stack

The last resource that we need to create is a DNS Record in our Route 53 hosted zone that will relate the domain www.example.com with the Cloudfront distribution.

WWWRecord:
   Type: AWS::Route53::RecordSet
   Properties:
     Name: !Sub 'www.${domain}'
     HostedZoneId: !Ref domainHostedZone
     Type: A
     AliasTarget:
       HostedZoneId: Z2FDTNDATAQYW2
       DNSName: !Ref wwwCloudfrontDomain

When we create a DNS Record which target is a Cloudfront distribution the Hosted Zone ID is always Z2FDTNDATAQYW2

Deployment

To create all the resources we just need to go to Cloudformation and follow the next steps:

  1. Select Create Stack → With new Resources (standard)
  2. Select the option Template is ready
  3. Specify S3 as a template source
  4. Paste the URL to the master template in your resources bucket, for example https://my-resources-bucket.s3.us-east-1.amazonaws.com/templates/master.yml

Conclusion

With this simple and cost-effective configuration, we can redirect the typical www to its apex domain.

This configuration is also reversible, therefore with a few modifications in the templates, you could get the opposite, redirect from apex domain to www.

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