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Mohamed Youssef
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# Cloudflare DNS Updater
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A Bash script that automatically updates Cloudflare DNS A records with your current public IP address. This script demonstrates various advanced Bash programming features while providing a practical tool for dynamic DNS management.
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## Features
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- **Automatic IP Detection**: Retrieves current public IP using external services
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- **Multi-Domain Support**: Manages DNS records for multiple domains simultaneously
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- **Smart Updates**: Only updates records when IP changes to avoid unnecessary API calls
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- **Orphaned Record Cleanup**: Automatically removes unmanaged DNS records
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- **Protected Records**: Prevents deletion of critical DNS records
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- **Dry Run Mode**: Test changes without actually modifying DNS records
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- **Comprehensive Logging**: Detailed output showing all operations performed
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## Bash Features Demonstrated
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This script showcases the following Bash programming features:
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### 1. **Shebang and Script Structure**
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```bash
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#!/bin/bash
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```
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Proper script initialization with bash interpreter specification.
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### 2. **Variable Declarations and Constants**
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```bash
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TOKEN=""
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AUTO_DELETE_ORPHANS=true
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DRY_RUN=false
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```
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Use of string constants and boolean flags for configuration.
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### 3. **Associative Arrays**
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```bash
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declare -A d0 d1 # Declare associative arrays for domain configuration
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d0=(
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["domain"]=""
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["zone_id"]=""
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["subdomains"]="@,"
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["protected_records"]=""
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)
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```
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Key-value data structures for complex domain configurations.
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### 4. **Indexed Arrays**
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```bash
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declare -a domains # Declare indexed array to hold domain references
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domains=( d0 d1 )
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```
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Ordered collections for managing multiple domains.
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### 5. **Array References (Namerefs)**
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```bash
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declare -n domain="$item" # Create reference to associative array
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echo "${domain[domain]}" # Access array elements through reference
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```
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Dynamic array referencing for flexible data access.
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### 6. **Functions**
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```bash
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get_current_ip() {
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curl -s https://ifconfig.me/ip
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}
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create_dns_record() {
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local zone_id="$1"
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local data="$2"
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# Function implementation
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}
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```
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Modular code organization with local variables and parameters.
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### 7. **Advanced Conditional Statements**
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```bash
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if [[ "$DRY_RUN" == true ]]; then
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echo "⚠️ DRY RUN MODE ENABLED"
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fi
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if [[ -n "${existing_a_records[$full_name]}" ]]; then
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# Record exists logic
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fi
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```
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String comparison, variable existence checks, and complex conditions.
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### 8. **Loop Constructs**
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```bash
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for item in "${domains[@]}"; do
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# Process each domain
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done
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for subdomain in "${managed_subdomains[@]}"; do
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# Process each subdomain
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done
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```
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Iteration over arrays with proper quoting.
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### 9. **String Manipulation and Parsing**
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```bash
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IFS=',' read -ra protected_records <<< "${domain[protected_records]}"
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IFS=',' read -ra managed_subdomains <<< "${domain[subdomains]}"
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```
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Field splitting and array population from comma-separated strings.
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### 10. **Command and Process Substitution**
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```bash
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current_ip=$(get_current_ip) # Command substitution
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done < <(echo "$response" | jq -c '.result[] | select(.type == "A")') # Process substitution
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```
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Capturing command output and feeding output to loops.
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### 11. **JSON Processing with jq**
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```bash
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if echo "$response" | jq -e '.success == false' > /dev/null 2>&1; then
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echo "Error: Failed to get DNS records"
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fi
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create_data=$(jq -n \
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--arg name "$full_name" \
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--arg ip "$current_ip" \
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'{
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"type": "A",
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"name": $name,
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"content": $ip,
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"ttl": 1,
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"proxied": true
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}')
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```
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Parsing JSON responses and constructing JSON payloads.
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### 12. **Error Handling and Exit Codes**
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```bash
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if [ -z "$current_ip" ]; then
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echo "Error: Could not retrieve current IP"
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exit 1
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fi
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```
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Input validation and controlled script termination.
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### 13. **Arithmetic Operations**
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```bash
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((records_created++))
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((records_updated++))
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((records_skipped++))
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((records_deleted++))
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```
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Counter variables for operation statistics.
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### 14. **API Integration with curl**
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```bash
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curl -s "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records" \
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-X POST \
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-H 'Content-Type: application/json' \
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-H "Authorization: Bearer $TOKEN" \
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-d "$data"
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```
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REST API calls with proper headers and data payloads.
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### 15. **Dynamic Variable Management**
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```bash
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unset existing_a_records # Clean up associative arrays
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unset domain # Clean up nameref
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```
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Memory management and variable cleanup.
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## Usage
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1. **Configure Domains**: Edit the domain arrays at the top of the script
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2. **Set API Token**: Update the `TOKEN` variable with your Cloudflare API token
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3. **Dry Run First**: Test with `DRY_RUN=true` to see what would change
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4. **Run Updates**: Set `DRY_RUN=false` to apply actual changes
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```bash
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# Dry run (safe testing)
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./update_domain.sh
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# Apply changes
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# Edit script: DRY_RUN=false
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./update_domain.sh
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```
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## Configuration
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### Domain Configuration Structure
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Each domain is configured as an associative array with:
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- `domain`: The root domain name
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- `zone_id`: Cloudflare zone identifier
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- `subdomains`: Comma-separated list of subdomains to manage
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- `protected_records`: Records that should never be deleted
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### Script Parameters
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- `TOKEN`: Cloudflare API bearer token
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- `AUTO_DELETE_ORPHANS`: Whether to remove unmanaged records
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- `DRY_RUN`: Test mode without making actual changes
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## Requirements
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- Bash 4.0+
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- curl
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- jq
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- Valid Cloudflare API token with DNS edit permissions
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## Security Notes
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- Store API tokens securely (consider environment variables)
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- Use dry run mode when testing
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- Review protected records configuration carefully
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- Monitor script output for any API errors
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## Output Example
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```
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⚠️ DRY RUN MODE ENABLED - No actual changes will be made
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=========================================
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Current Public IP: 203.0.113.1
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=========================================
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Processing domain: my-dev.pro
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Zone ID: 5c9a19af6aeababb78b294844290a7d2
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Managed subdomains: @ git
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----------------------------------------
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Existing A records:
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- my-dev.pro → 203.0.113.1 (ID: abc123)
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- git.my-dev.pro → 203.0.113.1 (ID: def456)
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----------------------------------------
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Checking: my-dev.pro
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✓ SKIPPED: IP unchanged (203.0.113.1 = 203.0.113.1)
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Checking: git.my-dev.pro
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✓ SKIPPED: IP unchanged (203.0.113.1 = 203.0.113.1)
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=========================================
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SUMMARY for my-dev.pro:
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✓ Created: 0
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✓ Updated: 0
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✓ Skipped (IP unchanged): 2
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✓ Deleted: 0
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=========================================
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⚠️ DRY RUN COMPLETED - No actual changes were made
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Set DRY_RUN=false to apply changes
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```
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