Use cloudflare as a dynamic dns with your own domain name (bash script)

cloudflare_dyndns

#!/bin/bash

## I use this script in a crontab that runs every couple of hours

## Get public IPv4 address with ipify API
PUBLIC_IP=$(curl --request GET --url https://api.ipify.org/)

## Replace auth key with your own cloudflare API key
AUTH_KEY=...
## Replace record name with the name of the (sub)domain you want to assign to the dynamic IP
RECORD_NAME=subdomain.example.com
TTL=120
## Replace with the id of the zone you want to change. Can be found in the cloudflare dashboard
ZONE_ID=...
## Replace with the id of the dns record corresponding to RECORD_NAME. Can be found by sending GET request to https://api.cloudflare.com/client/v4/zones/$ZONE_ID/dns_records
RECORD_ID=...
## PUT request to cloudflare
curl --request PUT \
  --url https://api.cloudflare.com/client/v4/zones/$ZONE_ID/dns_records/$RECORD_ID \
  --header "authorization: Bearer $AUTH_KEY" \
  --header 'content-type: application/json' \
  --data "{
        \"type\": \"A\",
        \"name\": \"$RECORD_NAME\",
        \"content\": \"$PUBLIC_IP\",
        \"ttl\": \"$TTL\"
}"