Dreamhost API Dynamic DNS cron script

_Dreamhost_Dynamic_DNS.md

1. sign up for a dreamhost API Key with "All DNS" permissions at https://panel.dreamhost.com/index.cgi?tree=home.api
2. copy config.sh to /etc/dreamhost/config.sh and fill out the variables
3. copy ddns.sh to /usr/local/dreamhost/ddns.sh
4. copy dreamhost_cron to /etc/cron.d/dreamhost_cron

config.sh

#!/bin/sh
# file location: /etc/dreamhost/config.sh

KEY="AAA1112223334444"                              # dreamhost api key
DDNS_SUBDOMAIN="subdomain.example.com"              # dynamic dns subdomain
DDNS_INTERFACE="eth0"                               # interface to use IPV4 from
DDNS_LAST_IP_FILE="/var/lib/dreamhost/last_ip.txt"  # file to store most recent IPV4 in

ddns.sh

#!/bin/sh
# file location /usr/local/dreamhost/ddns.sh

source /etc/dreamhost/config.sh

last_ip=""
if [ -f $DDNS_LAST_IP_FILE ]
then
  last_ip=$( cat $DDNS_LAST_IP_FILE | head -n 1 | awk '{ print $1}' )
fi

ip=$( ifconfig $DDNS_INTERFACE | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}' )

if [ "$ip" != "$last_ip" ]
then
  echo "Updating IP Address to $ip" 
  dh_last_ip=$(curl -s -H "Content-Type: application/x-www-form-urlencoded" -X POST -d \
    "key=$KEY&cmd=dns-list_records" \
    https://api.dreamhost.com/ \
    | grep $DDNS_SUBDOMAIN | cut -d: -f2 | awk '{print $5}')
  curl -s -H "Content-Type: application/x-www-form-urlencoded" -X POST -d \
    "key=$KEY&cmd=dns-remove_record&record=$DDNS_SUBDOMAIN&type=A&value=$dh_last_ip" \
    https://api.dreamhost.com/
  curl -s -H "Content-Type: application/x-www-form-urlencoded" -X POST -d \
    "key=$KEY&cmd=dns-add_record&record=$DDNS_SUBDOMAIN&type=A&value=$ip" \
    https://api.dreamhost.com/
  mkdir -p $( dirname $DDNS_LAST_IP_FILE )
  echo "$ip" > $DDNS_LAST_IP_FILE
fi

dreamhost_cron

# file location /etc/cron.d/dreamhost_cron
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

* * * * * root /bin/bash /usr/local/dreamhost/ddns.sh