BASH Script to keep Route53 updated with your current external IP address

.gitignore

*.ip
*.log

update-route53.sh

#!/bin/bash

usage=$(cat <<"EOF"
Usage:
    ./update-route53.sh [--help] --record=<record_set_name>
                        [--ttl=<ttl_seconds>] [--type=<record_type>]
                        --zone=<zone_id>

Update an AWS Route 53 record with your external IP address.

OPTIONS
    --help
        Show this output

    --record=<record_set_name>
        The name of the record set to update (e.g., hello.example.com).

    --ttl=<ttl_seconds>
        The TTL (in seconds) to set on the DNS record. Defaults to 300.

    --type=<record_type>
        The type of the record set to be updated (e.g., A, AAAA). Defaults to A.

    --zone=<zone_id>
        The zone id of the domain to be updated (e.g., ABCD12EFGH3IJ).

    --profile=<profile_name>
        The name of the `awscli` profile to use, if any (e.g., testing).
        (See: https://github.com/aws/aws-cli#getting-started)
EOF
)

SHOW_HELP=0
ZONEID=""
RECORDSET=""
PROFILE=""
PROFILEFLAG=""
TYPE="A"
TTL=300
COMMENT="Auto updating @ `date`"

while [ $# -gt 0 ]; do
    case "$1" in
        --help)
            SHOW_HELP=1
            ;;
        --record=*)
            RECORDSET="${1#*=}"
            ;;
        --ttl=*)
            TTL="${1#*=}"
            ;;
        --type=*)
            TYPE="${1#*=}"
            ;;
        --zone=*)
            ZONEID="${1#*=}"
            ;;
        --profile=*)
            PROFILE="${1#*=}"
            ;;
        *)
            SHOW_HELP=1
    esac
    shift
done

if [  -z "$RECORDSET" -o -z "$ZONEID" ]; then
    SHOW_HELP=1
fi

if [ $SHOW_HELP -eq 1 ]; then
    echo "$usage"
    exit 0
fi

if [ -n "$PROFILE" ]; then
    PROFILEFLAG="--profile $PROFILE"
fi

# Get the external IP address from OpenDNS (more reliable than other providers)
IP=`dig +short myip.opendns.com @resolver1.opendns.com`

# Get the current ip address on AWS
# Requires jq to parse JSON output
AWSIP="$(
   aws $PROFILEFLAG route53 list-resource-record-sets \
      --hosted-zone-id "$ZONEID" --start-record-name "$RECORDSET" \
      --start-record-type "$TYPE" --max-items 1 \
      --output json | jq -r \ '.ResourceRecordSets[].ResourceRecords[].Value'
)"


function valid_ip()
{
    local  ip=$1
    local  stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
            && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
        stat=$?
    fi
    return $stat
}

# Get current dir
# (from http://stackoverflow.com/a/246128/920350)
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
LOGFILE="$DIR/update-route53.log"
IPFILE="$DIR/update-route53__${ZONEID}__${RECORDSET}__.ip"

if ! valid_ip $IP; then
    echo "Invalid IP address: $IP" >> "$LOGFILE"
    exit 1
fi

# Check if the IP has changed
if [ ! -f "$IPFILE" ]
    then
    touch "$IPFILE"
fi
#compare local IP to dns of recordset
if [ "$IP" ==  "$AWSIP" ]; then
    # code if found
    # echo "IP is still $IP. Exiting" >> "$LOGFILE"
    exit 0
else
    echo "IP has changed to $IP" >> "$LOGFILE"
    # Fill a temp file with valid JSON
    TMPFILE=$(mktemp /tmp/temporary-file.XXXXXXXX)
    cat > ${TMPFILE} << EOF
    {
      "Comment":"$COMMENT",
      "Changes":[
        {
          "Action":"UPSERT",
          "ResourceRecordSet":{
            "ResourceRecords":[
              {
                "Value":"$IP"
              }
            ],
            "Name":"$RECORDSET",
            "Type":"$TYPE",
            "TTL":$TTL
          }
        }
      ]
    }
EOF

    # Update the Hosted Zone record
    aws $PROFILEFLAG route53 change-resource-record-sets \
        --hosted-zone-id $ZONEID \
        --change-batch file://"$TMPFILE" \
        --query '[ChangeInfo.Comment, ChangeInfo.Id, ChangeInfo.Status, ChangeInfo.SubmittedAt]' \
        --output text >> "$LOGFILE"
    echo "" >> "$LOGFILE"

    # Clean up
    rm $TMPFILE
fi

# All Done - cache the IP address for next time
echo "$IP" > "$IPFILE"

Since you're pulling the IP address directly from Route53 (which is great btw), you could probably remove the IPFILE

Thanks for cleaning this script up! Really nice to have everything go through as parameters

Very useful. Thanks a lot for sharing!

Nice script! I've made a change on getting IP from ResourceRecordSet using query and output to text:
aws $PROFILEFLAG route53 list-resource-record-sets \ --hosted-zone-id "$ZONEID" \ --query "ResourceRecordSets[?Name=='$RECORDSET.'].ResourceRecords[0].Value" \ --output text --no-cli-pager | tr -d '\r' )"

And another change on converting the IP string into array using readarray:
readarray -td. ip <<< "$ip." ; unset 'ip[-1]'