a shell script to update cloudflare's DNS record

update-cloudflare.sh

#!/bin/sh

# This is probably better implemented in a real scripting language like powershell script or javascript but 
# as a shell script to take minimal dependencies

###### Inputs - change these per your use case
# Go get Zone ID and account ID, log into the CF dashboard -> domain -> overview -> left column, bottom part
zone_identifier=000000000000000000000000000000
# The record we want to update
dns_name=example.com
dns_type="A"
# From https://dash.cloudflare.com -> profile -> token
cloudflare_auth_token=000000000000000000000000000000
log_dir=~/cloudflare-dns-update
#######################

########################
# Cloudflare API Documentation : https://api.cloudflare.com/#dns-records-for-a-zone-update-dns-record

########################
# Check jq dependency
jq_command=$(command -v jq)
if [ "$jq_command" = "" ]; then
    echo "The JSON parsing tool \"jq\" not found, proceeding to install it ..."
    # only supporting debian/ubuntu for now, adapt as needed
    sudo apt-get install jq
fi

if [ ! -d "$log_dir" ]; then
    echo "Log folder at $log_dir not found, creating it now ..."
    mkdir -p $log_dir
fi

########################
# Get Zone ID (note `apt install jq` to parse the returned json)
dns_record_identifier_api=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?type=$dns_type&name=$dns_name&match=all" \
    -H "Authorization: Bearer $cloudflare_auth_token" \
    -H "Content-Type: application/json" \
| jq -r ".result[0].id")
echo "DNS Record: type=$dns_type name=$dns_name has CloudFlare Zone ID=$dns_record_identifier_api"

########################
# Check if IP has changed since last update
hourstamp=$(date +"%F-%H")
past_ip=$(cat $log_dir/publicip.log)
publicip=$(curl https://api.ipify.org 2>/dev/null)
echo $publicip > $log_dir/publicip.log
if [ "$past_ip1" = "$publicip" ]; then
    echo "$(date) : IP Address of $dns_name not changed."
    echo "$(date) : IP Address of $dns_name not changed." >> $log_dir/$dns_name.$dns_type.log
    exit 0
fi

########################
# Update record
code=$(curl -s -X PUT https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$dns_record_identifier_api \
    -H "Authorization: Bearer $cloudflare_auth_token" \
    -H "Content-Type: application/json" \
    --data '{"type":'\"$dns_type\"',"name":'\"$dns_name\"',"content":'\"$publicip\"',"ttl":1}')

if [ $(echo $code | jq -r ".success") = "true" ]
then    
    # record public IP after update to server
    echo $publicip > $log_dir/publicip.log
    echo "$(date) : Updated $dns_type record of $dns_name to $publicip"
    echo "$(date) : Updated $dns_type record of $dns_name to $publicip" >> $log_dir/$dns_name.$dns_type.log
else
    echo "$(date) : FAILED to update record of $dns_name to $publicip"
    echo "$(date) : FAILED to update record of $dns_name to $publicip" >> $log_dir/$dns_name.$dns_type.log
    echo $code | jq -r
    exit 1
fi

exit 0