A bash script to update a Cloudflare DNS A record with the external IP of the source machine

cloudflare-ddns-update.sh

#!/bin/bash

# A bash script to update a Cloudflare DNS A record with the external IP of the source machine
# Used to provide DDNS service for my home
# Needs the DNS record pre-creating on Cloudflare

# Proxy - uncomment and provide details if using a proxy
#export https_proxy=http://<proxyuser>:<proxypassword>@<proxyip>:<proxyport>

# Cloudflare zone is the zone which holds the record
zone=example.com
# DNS record is the A record which will be updated
dnsrecord=www.example.com

## Cloudflare authentication details
## Get Auth Key from Profile > API Tokens > Global API key
cloudflare_auth_email=me@cloudflare.com
cloudflare_auth_key=1234567890abcdef1234567890abcdef

#Variables for Logging messages (location and timestamp format)
#Ensure you have permissions to write to the Logfile
LOGFILE="/var/log/syslog"
TIMESTAMP=`date "+%Y-%m-%d %H:%M:%S"`

# Get the current external IP address
ip=$(curl -s -X GET https://checkip.amazonaws.com)

echo "$TIMESTAMP CLOUDFLARE-SCRIPT : Current IP is $ip" | tee -a $LOGFILE

if host $dnsrecord 1.1.1.1 | grep "has address" | grep "$ip"; then
  echo "$TIMESTAMP CLOUDFLARE-SCRIPT : $dnsrecord is currently set to $ip; no changes needed" | tee -a $LOGFILE
  exit
fi

# if here, the dns record needs updating

# get the zone id for the requested zone
zoneid=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=$zone&status=active" \
  -H "X-Auth-Email: $cloudflare_auth_email" \
  -H "X-Auth-Key: $cloudflare_auth_key" \
  -H "Content-Type: application/json" | jq -r '{"result"}[] | .[0] | .id')

echo "$TIMESTAMP CLOUDFLARE-SCRIPT : Zone ID for $zone is $zoneid" | tee -a $LOGFILE

# get the dns record id
dnsrecordid=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zoneid/dns_records?type=A&name=$dnsrecord" \
  -H "X-Auth-Email: $cloudflare_auth_email" \
  -H "X-Auth-Key: $cloudflare_auth_key" \
  -H "Content-Type: application/json" | jq -r '{"result"}[] | .[0] | .id')

echo "$TIMESTAMP CLOUDFLARE-SCRIPT : DNS Record ID for $dnsrecord is $dnsrecordid" | tee -a $LOGFILE

# update the record
curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zoneid/dns_records/$dnsrecordid" \
  -H "X-Auth-Email: $cloudflare_auth_email" \
  -H "X-Auth-Key: $cloudflare_auth_key" \
  -H "Content-Type: application/json" \
  --data "{\"type\":\"A\",\"name\":\"$dnsrecord\",\"content\":\"$ip\",\"ttl\":1,\"proxied\":false}" | jq