Cloudflare API v4 Dynamic DNS Update for both IPv4 and IPv6 in Bash

cf-ddns.sh

#!/bin/bash

LOGTIME=$(date "+%Y-%m-%d %H:%M:%S")

# CHANGE THESE
auth_email="user@example.com"
auth_key="c2547eb745079dac9320b638f5e225cf483cc5cfdda41" # find in cloudflare account settings
record_name="www.example.com"
zone_identifier="023e105f4ecef8ad9ca31a8372d0c353" # get zone ID via API and store it here
record_identifier_ipv4="372e67954025e0ba6aaa6d586b9e0b59" # use List DNS Records api to get record id, link below ↓
record_identifier_ipv6="372e67954025e0ba6aaa6d586b9e0b5a" # https://api.cloudflare.com/#dns-records-for-a-zone-list-dns-records

# Get zone ID
#domain_name=example.com
#zone=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=${domain_name}&status=active&page=1&per_page=20&order=status&direction=desc&match=all" \
#                       -H "X-Auth-Email: ${auth_email}" \
#                       -H "X-Auth-Key: ${auth_key}" \
#                       -H "Content-Type: application/json")
#zone_identifier=${zone:18:32}
#echo $zone_identifier

# List DNS Records                                                                                                      
#records=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/${zone_identifier}/dns_records" \
#                       -H "X-Auth-Email: ${auth_email}" \
#                       -H "X-Auth-Key: ${auth_key}" \
#                       -H "Content-Type: application/json")
#echo $records | jq

# MAYBE CHANGE THESE                                                                                                                                                                                                                                                            
ipv4=$(curl -s https://ipv4.icanhazip.com)
# ipv6=$(curl -s https://ipv6.icanhazip.com)
ipv6=$(/sbin/ip -6 addr | grep inet6 | awk -F '[ \t]+|/' '{print $3}' | grep -v ^::1 | grep -v ^f | head -1)
# /sbin/ip -6 addr show eth0 (to specify eth0)

# SCRIPT START                                                                                                                                                                                                                                                                  
update_ipv4=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_identifier_ipv4" \
                   -H "X-Auth-Email: $auth_email" \
                   -H "X-Auth-Key: $auth_key" \
                   -H "Content-Type: application/json" \
                   --data "{\"id\":\"$zone_identifier\",\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ipv4\"}")

update_ipv6=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_identifier_ipv6" \
                   -H "X-Auth-Email: $auth_email" \
                   -H "X-Auth-Key: $auth_key" \
                   -H "Content-Type: application/json" \
                   --data "{\"id\":\"$zone_identifier\",\"type\":\"AAAA\",\"name\":\"$record_name\",\"content\":\"$ipv6\"}")

if [[ $update_ipv4 == *"\"success\":false"* ]]; then
    message="API UPDATE A RECORD  FAILED. DUMPING RESULTS:\n$update_ipv4"
    echo -e "['$LOGTIME'] $message"
    exit 1
else
    message="A record updated to: $ipv4"
    echo "['$LOGTIME'] $message"
fi

if [[ $update_ipv6 == *"\"success\":false"* ]]; then
    message="API UPDATE AAAA RECORD FAILED. DUMPING RESULTS:\n$update_ipv6"
    echo -e "['$LOGTIME'] $message"
    exit 1
else
    message="AAAA record updated to: $ipv6"
    echo "['$LOGTIME'] $message"
fi

https://gist.github.com/HackingGate/2276b69d52839fef1603132b4de941f0#file-cf-ddns-sh-L40
Make sure to correct $update_ipv4 to $update_ipv6 to see correct error if there is any when IPv6 fails to update.

Thanks for noticing.