Bash script to update Cloudflare DNS records to the current ip

update_ip.sh

#!/bin/bash

api_token="" #Cloudflare API Token
zone_identifier="" #Zone ID

record_name="" #the dns records name (e.g. example.com)

ttl=1 #Time to live, in seconds (60-86400 or 1 for automatic)
proxied=true #whether the record should proxied by Cloudflare (true|false)

ip4=$(dig @resolver1.opendns.com A myip.opendns.com +short -4)      #get current ipv4
ip6=$(dig @resolver1.opendns.com AAAA myip.opendns.com +short -6)   #get current ipv6

log_file="/var/log/update_ip.log"
log() {
    if [ "$1" ]; then
        echo -e "[$(date)] - $1" >> $log_file
    fi
}

update_ip4() {
    #check if ip is valid ipv4 address
    ipv4_regex='^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$'
    if [[ $ip4 =~ $ipv4_regex ]]; then
        A_data=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?name=$record_name&type=A" -H "Authorization: Bearer $api_token" -H "Content-Type: application/json")
        #get the ip of the dns record
        A_ip=$(echo $A_data | grep -Po '(?<="content":")[^"]*')
        #update if A record different
        if [[ $ip4 != $A_ip ]]; then
            A_identifier=$(echo $A_data | grep -Po '(?<="id":")[^"]*')
            update=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$A_identifier" -H "Authorization: Bearer $api_token" -H "Content-Type: application/json" --data "{\"id\":\"$zone_identifier\",\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ip4\",\"ttl\":$ttl,\"proxied\":$proxied}")
            if [[ $update == *"\"success\":false"* ]]; then
                message="Update failed:\n$update"
                log "$message"
                echo -e "$message"
                exit 1
            else
                message="IPv4 changed to: $ip4"
                log "$message"
                echo "$message"
            fi
        else
            if [ -t 1 ]; then
                echo $ip4
            fi
        fi
    else
        message="Can not get current ipv4 address"
        log "$message"
        echo "$message"
    fi
}
update_ip6() {
    #check if ip is valid ipv4 address
    ipv6_regex='^([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}$'
    if [[ $ip6 =~ $ipv6_regex ]]; then
        AAAA_data=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?name=$record_name&type=AAAA" -H "Authorization: Bearer $api_token" -H "Content-Type: application/json")
        #get the ip of the dns record
        AAAA_ip=$(echo $AAAA_data | grep -Po '(?<="content":")[^"]*')
        #update if AAAA record different
        if [[ $ip6 != $AAAA_ip ]]; then
            AAAA_identifier=$(echo $AAAA_data | grep -Po '(?<="id":")[^"]*')
            update6=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$AAAA_identifier" -H "Authorization: Bearer $api_token" -H "Content-Type: application/json" --data "{\"id\":\"$zone_identifier\",\"type\":\"AAAA\",\"name\":\"$record_name\",\"content\":\"$ip6\",\"ttl\":$ttl,\"proxied\":$proxied}")
            if [[ $update6 == *"\"success\":false"* ]]; then
                message="Update failed:\n$update6"
                log "$message"
                echo -e "$message"
                exit 1
            else
                message="IPv6 changed to: $ip6"
                log "$message"
                echo "$message"
            fi
        else
            if [ -t 1 ]; then
                echo $ip6
            fi
        fi
    else
        message="Can not get current ipv6 address"
        log "$message"
        echo "$message"
    fi
}

case $1 in
    4)  update_ip4  ;;
    6)  update_ip6  ;;
    *)
        update_ip4
        update_ip6
        ;;
esac