This script retrieves the current public IP address and updates the corresponding A records in Cloudflare DNS if they differ, using the Cloudflare API and the jq tool for JSON processing.

cloudflare_ip_update.sh

#!/bin/bash

# Access the environment variables
api_token="CLOUDFLARE_API_TOKEN"
zone_name="FQDN"

# Function to get the current public IP address
get_public_ip() {
    curl -s -X GET https://ifconfig.co
}

# Function to get the zone ID
get_zone_id() {
    local response
    response=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=$zone_name" \
        -H "Authorization: Bearer $api_token" \
        -H "Content-Type: application/json")

    if [[ $(echo "$response" | jq -r '.success') == "false" ]]; then
        echo "Error retrieving zone ID: $(echo "$response" | jq -r '.errors')"
        exit 1
    fi

    echo "$response" | jq -r '.result[0].id'
}

# Function to fetch all A records
get_a_records() {
    local zone_id="$1"
    local response
    response=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records?type=A" \
        -H "Authorization: Bearer $api_token" \
        -H "Content-Type: application/json")

    if [[ $(echo "$response" | jq -r '.success') == "false" ]]; then
        echo "Error fetching A records: $(echo "$response" | jq -r '.errors')"
        exit 1
    fi

    echo "$response" | jq -c '.result[]'
}

# Function to install jq
install_jq() {
    if command -v apt &> /dev/null; then
        echo "Installing jq using apt..."
        sudo apt update && sudo apt install -y jq
    elif command -v dnf &> /dev/null; then
        echo "Installing jq using dnf..."
        sudo dnf install -y jq
    elif command -v yum &> /dev/null; then
        echo "Installing jq using yum..."
        sudo yum install -y jq
    elif command -v apk &> /dev/null; then
        echo "Installing jq using apk..."
        sudo apk add jq
    elif command -v pacman &> /dev/null; then
        echo "Installing jq using pacman..."
        sudo pacman -Sy --noconfirm jq
    elif command -v brew &> /dev/null; then
        echo "Installing jq using Homebrew..."
        brew install jq
    else
        echo "Error: Could not detect package manager!"
        return 1
    fi
}

# Check for jq installation
if ! command -v jq &> /dev/null; then
    echo "jq is not installed. Attempting to install..."
    install_jq
    # Verify installation
    if ! command -v jq &> /dev/null; then
        echo "Failed to install jq. Please install it manually."
        exit 1
    fi
    echo "jq has been successfully installed."
else
    echo "jq is already installed."
fi

# Main script logic
ipv4=$(get_public_ip)

if [ -z "$ipv4" ]; then
    echo "Unable to retrieve public IP address."
    exit 1
fi

echo "Current public IP: $ipv4"

zone_id=$(get_zone_id)
if [ -z "$zone_id" ]; then
    echo "Zone ID is null. Please check the zone name and API token permissions."
    exit 1
fi

# Fetch all A records
records=$(get_a_records "$zone_id")

# Loop through each record and update if necessary
while IFS= read -r record; do
    name=$(echo "$record" | jq -r '.name')
    record_id=$(echo "$record" | jq -r '.id')
    current_ip=$(echo "$record" | jq -r '.content')
    proxied=$(echo "$record" | jq -r '.proxied')
    ttl=$(echo "$record" | jq -r '.ttl // 1')

    if [ "$current_ip" != "$ipv4" ]; then
        echo "Updating $name from $current_ip to $ipv4..."
        update_response=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records/$record_i>            -H "Authorization: Bearer $api_token" \
            -H "Content-Type: application/json" \
            --data "{\"type\":\"A\",\"name\":\"$name\",\"content\":\"$ipv4\",\"ttl\":$ttl,\"proxied\":$proxied}")

        if [[ $(echo "$update_response" | jq -r '.success') == "true" ]]; then
            echo "✓ Successfully updated $name ($current_ip -> $ipv4)"
        else
            echo "✗ Failed to update $name: $(echo "$update_response" | jq -r '.errors')"
        fi
    else
        echo "✓ $name is up to date ($current_ip)"
    fi
done <<< "$records"