Apex Redirect module for Terraform AWS

Before you begin

Regarding IPv6

Please note that Terraform currently has an issue with how it records the subnet_mapping when using both EIPs and IPv6. As a result when Terraform generates it's plan the NLB will be recreated; therefore, we have added a life-cycle exception to the subnet_mapping property so that changes will be ignored. This means, YOU as the engineer will need to take direct action to destroy and create the NLB when changes occur to the subnet_mapping. This does not apply to IPv4 only configurations.

Purpose

If the root of your DNS is serviced by another DNS provider, i.e. an external DNS or AWS account outside of your application environment, you might run into an obscure quirk with DNS.

• The Apex domain, such as example.com, by DNS specification must be an A record.
• A records must be IP addresses (not hostnames)
• If DNS for example.com is managed outside of your AWS account, you must provide them with an IP address to populate the A record
• If you're using a Load Balancer, CloudFront, or anything else without static IPs on AWS, this is a problem.
  • Typically, this issue would be resolved by Alias records in Route53, but that's not an option if your DNS is handled externally

The solution for this is to create a small service at your Apex domain example.com that does nothing but redirect viewers to a subdomain www.example.com

• Your service would have a small set of Static IPs
• The service issues 301 Redirects to send viewers to the subdomain
• This takes very little processing power, but can be a hassle to configure
• If your application operates over TLS (HTTPS), there are additional configurations to maintain [cert rotation, tls configuration]

We historically have done this with a single EC2 instance with an Elastic IP, but...

• This means our EC2 instance is a single point of failure
• Managing the AMI lifecycle (Creation, Updating, Rebuilding) was tedious
• Doing this for a single instance was tolerable, but didn't scale to each domain
• Things kept going wrong

Needing to workaround all of this led us to create this module.

Usage

See our examples directory

Contributing

We welcome contributions. To contribute please read our CONTRIBUTING document. All contributions are subject to the license and in no way imply compensation for contributions.

Terraform 0.12

Our code base now exists in Terraform 0.13 and we are halting new features in the Terraform 0.12 major version. If you wish to make a PR or merge upstream changes back into 0.12, please submit a PR to the terraform-0.12 branch.

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