Cloudflare DNS record update via bash (for DDNS like behaviour)

cloudflare_ddns.sh

#!/usr/bin/env bash

DDNS_DIR='/tmp/cf_ddns'
PREVIOUS_IP_FILE="$DDNS_DIR/dynamic_ip.txt"
CF_REQUEST_RESPONSE_FILE="$DDNS_DIR/cf_response.json"

mkdir -p "$DDNS_DIR"
[ ! -f "$PREVIOUS_IP_FILE" ] && touch "$PREVIOUS_IP_FILE"

# NEW_IP="$(dig +short myip.opendns.com @resolver1.opendns.com)"
NEW_IP="$(curl -s checkip.amazonaws.com)"
PREVIOUS_IP="$(cat $PREVIOUS_IP_FILE)"

CF_EMAIL="[email protected]"                      # Email address for CF account
CF_ZONE_ID="the-zone-id-for-your-domain"            # The Zone ID for your domain/zone
CF_API_KEY="your-cloudflare-global-api-key"         # Your CF Global API key - careful with this
CF_DNS_RECORD_ID="the-record-id-for-your-entry"     # Check CF api to get this
CF_DNS_RECORD_TYPE="the-record-type-for-your-entry" # A / CNAME etc.
CF_DNS_RECORD_NAME="somedomain.here"                # The domain/zone name

if [ "$NEW_IP" = "$PREVIOUS_IP" ]; then
  echo "IP address NOT changed : $NEW_IP"
else
  echo "IP address has changed : $NEW_IP"
  echo "Updating DNS record..."
  curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$CF_ZONE_ID/dns_records/$CF_DNS_RECORD_ID" \
    -H "X-Auth-Email: $CF_EMAIL" \
    -H "X-Auth-Key: $CF_API_KEY" \
    -H "Content-Type: application/json" \
    --data "{\"type\":\"$CF_DNS_RECORD_TYPE\",\"name\":\"$CF_DNS_RECORD_NAME\",\"content\":\"$NEW_IP\"}" \
    > "$CF_REQUEST_RESPONSE_FILE"
  if grep --quiet '"success":true' "$CF_REQUEST_RESPONSE_FILE"; then
    echo "Sucessfully updated DNS record..."
    echo "$NEW_IP" > "$PREVIOUS_IP_FILE"
  else
    echo "Could not update DNS record..."
    cat "$CF_REQUEST_RESPONSE_FILE"
    exit 1
  fi
fi