route53_change_cname.rb

credentials_hash = {
  aws_secret_access_key: "KEY",
  aws_access_key_id: "ID"
}

route53 = Fog::DNS::AWS.new(credentials_hash)
resource_record_sets = route53.list_resource_record_sets("ZONE_ID")
data = resource_record_sets.data[:body]["ResourceRecordSets"]
redis_resource_record = data.detect { |record_set| record_set["Name"] == "record_name_with_a_dot_at_the_end." }
former_cname_entry = redis_resource_record["ResourceRecords"].first

route53.change_resource_record_sets("ZONE_ID", [
  { action: "DELETE", :type => "CNAME", name: "record_name_with_a_dot_at_the_end.", ttl: 300, resource_records: [ former_cname_entry ] },
  { action: "CREATE", :type => "CNAME", name: "record_name_with_a_dot_at_the_end.", ttl: 300, resource_records: [ "NEW_CNAME" ] }
])