register a local hostname of an ec2 instance at route53 hosted zone (expects an IAM role)

ec2-route53.sh

# bash, coreutils, curl, awk, jq, openssl
zone=ZOZONEZONEZONE
date=$(curl -s -I https://route53.amazonaws.com/date | awk '/^Date: / {sub("Date: ", "", $0); sub("\\r", "", $0); print $0}')
set -- $(curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/dns | jq -r '.SecretAccessKey, .AccessKeyId, .Token')
signature=$(echo -n $date | openssl dgst -binary -sha1 -hmac $1 | base64)
auth_header="X-Amzn-Authorization: AWS3-HTTPS AWSAccessKeyId=$2,Algorithm=HmacSHA1,Signature=$signature"
hostname=$(hostname).doge-networking-enterprises.com
local_hostname=$(curl -s http://169.254.169.254/latest/meta-data/local-hostname)
{ cat <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<ChangeResourceRecordSetsRequest xmlns="https://route53.amazonaws.com/doc/2013-04-01/">
<ChangeBatch>
   <Changes>
      <Change>
         <Action>UPSERT</Action>
         <ResourceRecordSet>
            <Name>$hostname</Name>
            <Type>CNAME</Type>
            <TTL>30</TTL>
            <ResourceRecords>
               <ResourceRecord><Value>$local_hostname</Value></ResourceRecord>
            </ResourceRecords>
         </ResourceRecordSet>
      </Change>
   </Changes>
</ChangeBatch>
</ChangeResourceRecordSetsRequest>
EOF
} | curl -d @/dev/stdin -H "Content-Type: text/xml" -H "x-amz-date: $date" -H "$auth_header" -H "x-amz-security-token: $3" -X POST https://route53.amazonaws.com/2013-04-01/hostedzone/$zone/rrset