Creating our Let's Encrypt hook script

auth-hook.sh

aws route53 wait resource-record-sets-changed --id \
    $(aws route53 change-resource-record-sets --hosted-zone-id \
        "$(aws route53 list-hosted-zones-by-name --dns-name $2. \
        --query HostedZones[0].Id --output text)" \
      --query ChangeInfo.Id \
      --output text \
      --change-batch "{ \
        \"Changes\": [{ \
          \"Action\": \"$1\", \
          \"ResourceRecordSet\": { \
            \"Name\": \"_acme-challenge.${CERTBOT_DOMAIN}.\", \
            \"ResourceRecords\": [{\"Value\": \"\\\"${CERTBOT_VALIDATION}\\\"\"}], \
            \"Type\": \"TXT\", \
            \"TTL\": 30 \
          } \
        }] \
      }" \
    )

This script works fine -- in my case, errors came down to user error and not reading carefully enough. I think some of the confusion is that it's written for certbot to invoke, not manually and without arguments (hence the invalid XML operation error), and it requires modification to use your domain (as mentioned in article at Hackernoon, hence the mydomain.com related errors). Additionally, you must have Route 53 set up (as mentioned in the article).