Use Cloudflare's API to set Dynamic DNS records with Crontab

cloudflare_ddns.sh

#!/bin/sh

# Cloudflare API v.4 Variables
CF_APIKEY='Your API Key Here'
CF_ZONEID='The Zone ID here' # Found on your Cloudflare Dashboard
CF_DNSID='The DNS ID here' # Found by listing DNS with Cloudflare API, see below for command
CF_EMAIL='your@email.address'
CF_DNS='address.domain.com'
GET_IP=$(dig +short txt ch whoami.cloudflare @1.0.0.1)

# Make the request
curl -X PUT "https://api.cloudflare.com/client/v4/zones/${CF_ZONEID}/dns_records/${CF_DNSID}" \
     -H "X-Auth-Email: ${CF_EMAIL}" \
     -H "X-Auth-Key: ${CF_APIKEY}" \
     -H "Content-Type: application/json" \
     -d $'{"type":"A",
           "name":"'${CF_DNS}'",
           "content":'$GET_IP',
           "ttl":1,
           "proxied":false }'
     
# Optional, add to Crontab
# This runs every 5 minutes
# Set SCRIPT_LOCATION and LOGS_LOCATION to an absolute path like /home/username
#
# 0/5 * * * * /bin/sh SCRIPT_LOCATION/cloudflare_ddns.sh > LOGS_LOCATION/ddns.log 2>&1

# Optional, find Zone ID
# 
# curl -X GET "https://api.cloudflare.com/client/v4/zones/{CF_ZONEID}/dns_records" \
#      -H "Content-Type:application/json" \
#      -H "X-Auth-Key:${CF_APIKEY}" \
#      -H "X-Auth-Email:${CF_EMAIL}"