Automatically update your CloudFlare DNS record to the IP, Dynamic DNS for Cloudflare

cf-ddns.sh

#!/usr/bin/env bash
set -o errexit
set -o nounset
set -o pipefail

# Automatically update your CloudFlare DNS record to the IP, Dynamic DNS
# Can retrieve cloudflare Domain id and list zone's, because, lazy

# Place at:
# /usr/local/bin/cf-ddns.sh
# run `chomod +x cf-ddns.sh`
# run `crontab -e` and add next line:
# 0 * * * * /usr/local/bin/cf-ddns.sh >/dev/null 2>&1
# run /usr/local/bin/cf-ddns.sh in terminal to check all settings are valid

# Usage:
# cf-ddns.sh -k cloudflare-api-key \
#            -u user@example.com \
#            -h host.example.com \     # fqdn of the record you want to update
#            -z example.com \          # will show you all zones if forgot, but you need this

# Optional flags:
#            -i cloudflare-record-id \ # script will show this
#            -a true|false \           # auto get zone list and record id
#            -f false|true \           # force dns update, disregard local stored ip

# default config

# API key, see https://www.cloudflare.com/a/account/my-account,
# incorrect api-key results in E_UNAUTH error
CFKEY=

# Zone name, will list all possible if missing, eg: example.com
CFZONE=

# Domain id, will retrieve itself by default
CFID=

# Username, eg: user@example.com
CFUSER=

# Hostname to update, eg: homeserver.example.com
CFHOST=

# Cloudflare TTL for record, between 120 and 86400 seconds
CFTTL=3600
# Get domain ID from Cloudflare using awk/sed and python json.tool
GETID=true
# Ignore local file, update ip anyway
FORCE=false
# Site to retrieve WAN ip, other examples are: bot.whatismyipaddress.com, https://api.ipify.org/ ...
WANIPSITE="http://icanhazip.com"

# get parameter
while getopts a:k:i:u:h:z:f: opts; do
  case ${opts} in
    a) GETID=${OPTARG} ;;
    k) CFKEY=${OPTARG} ;;
    i) CFID=${OPTARG} ;;
    u) CFUSER=${OPTARG} ;;
    h) CFHOST=${OPTARG} ;;
    z) CFZONE=${OPTARG} ;;
    f) FORCE=${OPTARG} ;;
  esac
done

# If required settings are missing just exit
if [ "$CFKEY" = "" ]; then
  echo "Missing api-key, get at: https://www.cloudflare.com/a/account/my-account"
  echo "and save in ${0} or using the -k flag"
  exit 2
fi
if [ "$CFUSER" = "" ]; then
  echo "Missing username, probably your email-address"
  echo "and save in ${0} or using the -u flag"
  exit 2
fi
if [ "$CFHOST" = "" ]; then 
  echo "Missing hostname, what host do you want to update?"
  echo "save in ${0} or using the -h flag"
  exit 2
fi

# If the hostname is not a FQDN
if [ "$CFHOST" != "$CFZONE" ] && ! [ -z "${CFHOST##*$CFZONE}" ]; then
  CFHOST="$CFHOST.$CFZONE"
  echo " => Hostname is not a FQDN, assuming $CFHOST"
fi

# If CFZONE is missing, retrieve them all from CF
if [ "$CFZONE" = "" ]; then
  echo "Missing zone"
  if ! [ "$GETID" == true ]; then exit 2; fi
  echo "listing all zones: (if api-key is valid)"
  JSON=$(curl -s https://www.cloudflare.com/api_json.html \
       -d a=zone_load_multi \
       -d tkn=$CFKEY \
       -d email=$CFUSER | sed -e 's/":"/:/g')

  if [ -n "$(echo $JSON|grep -Po '"err_code:\K[^"]*')" ]; then
    echo "Error:" $(echo -e $JSON|grep -Po '"msg:\K[^"]*')
    exit 2
  fi

  for m in $(echo $JSON|grep -Po '"zone_name:\K[^"]*'); do
    echo "* $m"
  done

  echo "Please specify the matching zone in ${0} or specify using the -z flag"
  exit 2
fi

# Get current and old WAN ip
WAN_IP=`curl -s ${WANIPSITE}`
if [ -f $HOME/.wan_ip-cf.txt ]; then
  OLD_WAN_IP=`cat $HOME/.wan_ip-cf.txt`
else
  echo "No file, need IP"
  OLD_WAN_IP=""
fi

# If WAN IP is unchanged an not -f flag, exit here
if [ "$WAN_IP" = "$OLD_WAN_IP" ] && [ "$FORCE" = false ]; then
  echo "WAN IP Unchanged, to update anyway use flag -f true"
  exit 0
fi

# If CFID is missing retrieve and use it
if [ "$CFID" = "" ]; then
  echo "Missing DNS record ID"
  if ! [ "$GETID" == true ]; then exit 2; fi
  echo "fetching from Cloudflare..."

  JSON=$(curl -s https://www.cloudflare.com/api_json.html \
       -d a=rec_load_all \
       -d tkn=$CFKEY \
       -d email=$CFUSER \
       -d z=$CFZONE | sed -e 's/":"/:/g')

  if [ -n "$(echo $JSON|grep -Po '"err_code:\K[^"]*')" ]; then
    echo "Error:" $(echo -e $JSON|grep -Po '"msg:\K[^"]*')
    exit 2
  fi

  IDS=($(echo $JSON|grep -Po '"rec_id:\K[^"]*'))
  NAMES=($(echo $JSON|grep -Po '"name:\K[^"]*'))
  TYPES=($(echo $JSON|grep -Po '"type:\K[^"]*'))
  RECORDS="ID RECORD TYPE";

  for key in $(seq 0 $((${#IDS[@]}-1)) ); do
    if [ "${NAMES[$key]}" == "$CFHOST" ] && [ "${TYPES[$key]}" == "A" ]; then
      CFID=${IDS[$key]}
    fi
    RECORDS="${RECORDS}\n${IDS[$key]} ${NAMES[$key]} ${TYPES[$key]}"
  done
fi

# If WAN is changed, update cloudflare
echo "Updating DNS to $WAN_IP"
RESPONSE=$(
curl -s https://www.cloudflare.com/api_json.html \
  -d a=rec_edit \
  -d tkn=$CFKEY \
  -d email=$CFUSER \
  -d z=$CFZONE \
  -d id=$CFID \
  -d ttl=$CFTTL \
  -d type=A \
  -d name=$CFHOST \
  -d "content=$WAN_IP"
) 
if [ "$RESPONSE" != "${RESPONSE%success*}" ]; then
  echo "Updated succesfuly!"
  echo $WAN_IP > $HOME/.wan_ip-cf.txt
  exit
else
  echo 'Something went wrong :('
  echo "Response: $RESPONSE"
  exit 1
fi