Access 2 AWS API Gateways with single CNAME - amazon-web-services

Question

I have a hosted zone as customdomain.com and 2 regional API Gateways hosted on AWS.
I want to configure common CNAME as myapp.customdomain.com to call APIGW_REGION_ONE_EXECUTEAPI_URI and APIGW_REGION_TWO_EXECUTEAPI_URI based on latency.
How can I do this? I am confused between custom domain name on API Gateway vs Route 53 CNAME record. Any help or guidance is highly appreciated.

Answer 1

The custom domain name on API Gateway allows it to respond to names other than the AWS provided one (it works via SNI) and to also provide a certificate that has at least one SAN that will match your provided name so you will need to define that as well as any DNS records so that people can then resolve the API Gateway.
As for latency based records you will need to create multiple Route53 records and define the latency policy in each of them. The aws_route53_record docs show how you can create weighted records for shifting 10% of all traffic to a different target:
resource "aws_route53_record" "www-dev" {
zone_id = "${aws_route53_zone.primary.zone_id}"
name = "www"
type = "CNAME"
ttl = "5"
weighted_routing_policy {
weight = 10
}
set_identifier = "dev"
records = ["dev.example.com"]
}
resource "aws_route53_record" "www-live" {
zone_id = "${aws_route53_zone.primary.zone_id}"
name = "www"
type = "CNAME"
ttl = "5"
weighted_routing_policy {
weight = 90
}
set_identifier = "live"
records = ["live.example.com"]
}
In your case you are going to want something like this:
data "aws_region" "region_one" {}
data "aws_route53_zone" "selected" {
name = "example.com."
}
resource "aws_api_gateway_domain_name" "example" {
domain_name = "api.example.com"
certificate_name = "example-api"
certificate_body = "${file("${path.module}/example.com/example.crt")}"
certificate_chain = "${file("${path.module}/example.com/ca.crt")}"
certificate_private_key = "${file("${path.module}/example.com/example.key")}"
}
resource "aws_route53_record" "region_one" {
zone_id = "${data.aws_route53_zone.selected.zone_id}"
name = "${aws_api_gateway_domain_name.region_one.domain_name}"
type = "A"
latency_routing_policy {
region = "${data.aws_region.region_one.name}"
}
set_identifier = "${data.aws_region.region_one.name}"
alias {
name = "${aws_api_gateway_domain_name.region_one.regional_domain_name}"
zone_id = "${aws_api_gateway_domain_name.region_one.regional_zone_id}"
evaluate_target_health = true
}
}
And place that where you create each API Gateway or use multiple providers with different region configuration to apply both at the same time.