A bash script to bulk change all IP addresses of A record in all domains in one cloudflare account

cloudflare-DNS-bulk-update.sh

#!/bin/bash

old_ip="111.111.111.111"
new_ip="222.222.222.222"
email="my@cloudflare.com"
api_token="0123456789abcdefghijklmnopqrstuvwxyz1234"

zone_id_list=( $(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/?per_page=500" -H "X-Auth-Email: $email " -H "Authorization:Bearer $api_token " -H "Content-Type: application/json"| jq -r '.result[].id') )

for zone_id in "${zone_id_list[@]}"
do
        echo "zone_id is "$zone_id
        record_a_list=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/${zone_id}/dns_records?per_page=500&type=A&content=$old_ip " -H "X-Auth-Email: $email " -H "Authorization:Bearer $api_token " -H "Content-Type: application/json")

        record_a_ip=$(echo $record_a_list |  jq -r '{"result"}[] | .[0] | .content')

        echo "cloudflare dns ip is:" $record_a_ip

        if [  -n $record_a_ip   -a  $record_a_ip == $old_ip ]
        then
                 echo "change the A record"
                 record_list=$(echo $record_a_list |  jq -r '.result[].id')
                 for id in ${record_list}
                 do

                        echo "dns_records id is " $id
                        curl -s -X PATCH "https://api.cloudflare.com/client/v4/zones/${zone_id}/dns_records/${id}" -H "X-Auth-Email: $email " -H "Authorization:Bearer $api_token " -H "Content-Type: application/json" --data "{\"content\":\"$new_ip\"}"
                 done
        fi

done

record_a_ip=$(echo $record_a_list |  jq -r '{"result"}[] | .[0] | .content')

This will return only 1 record per zone. But there may be more than one record with $old_ip per zone. You can loop over the result like this:

while read NAME IP; do
	echo "Found $NAME ($IP)"

	# update records here
	# ......
done < <(jq -r '.result[] | [ .name, .content ] | @tsv' <<< "$record_a_list")