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

update-route53.sh

#!/bin/bash

# (optional) You might need to set your PATH variable at the top here
# depending on how you run this script
#PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# Hosted Zone ID e.g. BJBK35SKMM9OE
ZONEID="enter zone id here"

# The CNAME you want to update e.g. hello.example.com
RECORDSET="enter cname here"

# More advanced options below
# The Time-To-Live of this recordset
TTL=300
# Change this if you want
COMMENT="Auto updating @ `date`"
# Change to AAAA if using an IPv6 address
TYPE="A"

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

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.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

if grep -Fxq "$IP" "$IPFILE"; 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 route53 change-resource-record-sets \
        --hosted-zone-id $ZONEID \
        --change-batch file://"$TMPFILE" >> "$LOGFILE"
    echo "" >> "$LOGFILE"

    # Clean up
    rm $TMPFILE
fi

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

Thanks for the very helpful script. I tweaked the aws command to give me a consistent format in my log file. It took me a while to get the --query parameter right, so I thought I would share it here in case it helps someone.

aws 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"

This gives you a single line of plain text (no JSON formatting) output from the command in your log file.

Thanks for this! I ended up using curl -4sS "http://checkip.amazonaws.com" for my implementation. Running from Raspberry Pi Zero

I've adapted your gist for use in a Jenkins job - we've got a big instance that doesn't need to run all the time, so Jenkins shuts it down after hours. It then starts it up in the morning and runs this to update the DNS record so our staff has seamless access to it. https://gist.github.com/cterrykenzan/7fefc975851a80327323e1290e6a3c57

Executing this on a Raspberry pi with raspbian I got this error:

24: ./update-route53.sh Syntax error "(" unexpected

@Manuel5cc if you are using bash at the head of your script make sure you are executing the script in a bash shell.

I've merged some work from a few forks (@rosston's, @d90's, and @dominic-p's modification in the comments above); and added support for the awscli --profile flag (ideal for use with IAM users). My fork is here:

https://gist.github.com/ELLIOTTCABLE/071fef84be5adc46c11eee53db77fc23

While on the topic, here's the “managed policy” you should use for an IAM user that's specifically created to operate as your DynDNS client:

• Route 53: ListResourceRecordSets and Route 53: ChangeResourceRecordSets against arn:aws:route53:::hostedzone/ZB83EXAMPLEZONEID for every Zone ID your script will be running against,
• Route 53: GetChange against arn:aws:route53:::change/*

If you implement this as an IAM user, then the access-key/secret-key stored on your dynamic-DNS-updating-machine can't be used to screw with the rest of your account, if compromised.