create a subdomain using a CF template

cf_cname_subdomain.json

{
  "AWSTemplateFormatVersion" : "2010-09-09",

  "Description" : "AWS CloudFormation Template Route53_CNAME. This uses the patameters to create a subdomain CNAME",

  "Parameters" : {
    "HostedZone" : {
      "Type" : "String",
      "Description" : "The DNS name of an existing Amazon Route 53 hosted zone",
      "AllowedPattern" : "(?!-)[a-zA-Z0-9-.]{1,63}(?<!-)",
      "ConstraintDescription" : "must be a valid DNS zone name."
    },
    "SubdomainParam": {
      "Type": "String",
      "Description": "Enter the subdomain name for the stack you want mapped to the CNAME"
    },
    "LoadBalancerParam": {
      "Type": "String",
      "Description": "Enter the loadbalancer name for the stack you want mapped to the CNAME"
    }
  },

  "Resources" : {
    "SubdomainDNSRecord" : {
      "Type" : "AWS::Route53::RecordSet",
      "Properties" : {
        "HostedZoneName" : { "Fn::Join" : [ "", [{"Ref" : "HostedZone"}, "." ]]},
        "Comment" : "CNAME redirect to subdomain.",
        "Name" : { "Fn::Join" : [ "", [{"Ref" : "SubdomainParam"}, ".",  {"Ref" : "HostedZone"}, "."]]},
        "Type" : "CNAME",
        "TTL" : "900",
        "ResourceRecords" : [{
          "Ref": "LoadBalancerParam"
        }]
      }
    }
  },
  "Outputs" : {
    "CNAME" : {
      "Description" : "Fully qualified domain name",
      "Value" : { "Ref" : "SubdomainDNSRecord" }
    }
  }
}

create_r53_cname.sh

#!/usr/bin/env bash

aws cloudformation create-stack --profile default --stack-name stage-blog-cname  \
    --template-body file:///Users/claytongraham/data/github/dronze/dronze-cicd/cf/r53_cname.json \
    --parameters ParameterKey=HostedZone,ParameterValue=dronze.com \
        ParameterKey=SubdomainParam,ParameterValue=stage.blog \
        ParameterKey=LoadBalancerParam,ParameterValue=dronze-elb-PROD-1699664721.us-west-2.elb.amazonaws.com

create_r53_policy.json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": "cloudformation:*",
            "Effect": "Allow",
            "Resource": "arn:aws:cloudformation:us-west-2:715212546939:stack/*"
        },
        {
            "Action": "route53:*",
            "Effect": "Allow",
            "Resource": "arn:aws:route53:::hostedzone/Z3VRQF6A9GQX5I"
        },
        {
            "Action": "codepipeline:*",
            "Effect": "Allow",
            "Resource": "*"
        }
    ]
}

Basic pattern to create a CNAME via CF