DNS cutover: point api.fieldsofthe.world to prod, add api.dev.fieldsofthe.world

[asmithml]

Part of #33

Depends on: Deploy production infrastructure, Migrate DynamoDB data

Context

Currently api.fieldsofthe.world points to the dev CloudFront distribution (E1T5CMVYRBZH5U). After prod is deployed and data is migrated, DNS needs to switch so:

• api.fieldsofthe.world points to the new prod CloudFront distribution
• api.dev.fieldsofthe.world points to the existing dev CloudFront distribution

The Route53 hosted zone Z0262614UNLFJ5R8CSIF for api.fieldsofthe.world will be managed by the prod environment after the certificate-manager refactor.

Steps

1. Communicate maintenance window to users. DNS propagation is fast (CloudFront alias records) but the cert/domain swap may cause brief downtime.

2. Remove the custom domain from the dev environment:

   • Update environments/dev/terraform.tfvars: set custom_domain_name = "" temporarily
   • Run terraform apply in environments/dev/
   • This releases the api.fieldsofthe.world domain from the dev API Gateway and CloudFront

3. Apply prod environment (if not already done) which claims api.fieldsofthe.world:

   • Prod creates the Route53 zone and A record pointing to its CloudFront
   • Prod creates ACM certs and API Gateway custom domain for api.fieldsofthe.world

4. Update dev to use the new subdomain:

   • Update environments/dev/terraform.tfvars: set custom_domain_name = "api.dev.fieldsofthe.world"
   • Pass the prod-managed Route53 zone ID to the dev certificate-manager module
   • Run terraform apply in environments/dev/
   • This creates a new ACM cert for api.dev.fieldsofthe.world and adds the DNS record to the shared zone

5. Verify both endpoints:

   • curl https://api.fieldsofthe.world/v1/ returns the prod API
   • curl https://api.dev.fieldsofthe.world/v1/ returns the dev API

Risk

• Brief downtime on api.fieldsofthe.world during the domain swap (between steps 2 and 3)
• If ACM certificate validation takes time, the new cert must be validated before the domain works
• Rollback: re-apply dev with the original custom_domain_name to restore the previous state