A bash script to update an A record for a domain in Cloudflare to be the value of the current IP

update-cloudflare-ddns.sh

#!/bin/bash

zone_id=
# needs DNS read and write access
api_key=
# must also be in the given zone
record_name=example.com

ip=$(curl -s -X GET https://checkip.amazonaws.com)
record_id=$(curl -X GET "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records?type=A&name=$record_name" \
     -H "Authorization: Bearer $api_key" \
     -H "Content-Type:application/json" | jq -r '{"result"}[] | .[0] | .id')
curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records/$record_id" \
     -H "Authorization: Bearer $api_key" \
     -H "Content-Type:application/json" \
     --data "{\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ip\",\"ttl\":1,\"proxied\":false}"