Create Route53 A records using IAM profile with route53 access

linux-salt-bootstrap.sh

#!/bin/sh

# bootstrap script that runs on every system boot called via AWS instance user-data
# via 'curl -s http://169.254.169.254/latest/user-data | /bin/sh 2>&1'

# Make sure only root can run our script
if [ "$(id -u)" != "0" ]; then
    echo "This script must be run as root" 1>&2
    exit 1
fi

# route53 IP assignment requires an assigned IAM profile/role to the callign
# EC2 instance that includes the following policy
# {
#     "Version": "2012-10-17",
#     "Statement": [
#         {
#             "Effect": "Allow",
#             "Action": [
#                 "route53:ChangeResourceRecordSets",
#                 "route53:GetHostedZone",
#                 "route53:ListResourceRecordSets"
#             ],
#             "Resource": "arn:aws:route53:::hostedzone/<zone-id>"
#         },
#         {
#             "Effect": "Allow",
#             "Action": [
#                 "route53:GetChange",
#                 "route53:ListHostedZones"
#             ],
#             "Resource": "*"
#         }
#     ]
# }

TTL=600
EC2CMD='aws ec2 describe-tags'
APIURL='http://169.254.169.254/latest/meta-data'
AVAILZONE=$(curl -s ${APIURL}/placement/availability-zone)
REGION=${AVAILZONE%[a-z]}
RESOURCEID=$(curl -s ${APIURL}/instance-id)
MNAME=$(${EC2CMD} --region=${REGION} --filters "Name=resource-id,Values=${RESOURCEID}" "Name=key,Values=Name" --output=text | cut -f5 | tr -d '\n')
DOMAIN='example.com'
HOSTNAME=${MNAME%.${DOMAIN}}
HOSTIP=$(curl -s ${APIURL}/local-ipv4)

hostname ${HOSTNAME}
echo ${HOSTNAME} > /etc/hostname

cat<<EOF > /etc/hosts
# This file is automatically genreated by ec2-hostname script
127.0.0.1 localhost
${HOSTIP} ${HOSTNAME}.${DOMAIN} ${HOSTNAME}

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts
EOF

# Create a new CNAME record on Route 53, replacing the old entry if nessesary
if [ ! -z "${HOSTNAME}" ] && [ ! -z "${HOSTIP}" ]; then
    cli53 rrcreate "${DOMAIN}" "${HOSTNAME}" A "${HOSTIP}" --replace --ttl "${TTL}"
fi

Saweet!