json-leases-to-unbound 0.0.1

Monitor JSON lease files and sync them to Unbound DNS server

json-leases-to-unbound

A Python service that monitors JSON lease files and automatically synchronizes them to an Unbound DNS server in real-time. This tool bridges the gap between DHCP/SLAAC lease management systems and local DNS resolution.

Features

• 🔄 Real-time Monitoring - Watches lease directories for changes using filesystem events
• 🌐 IPv4 & IPv6 Support - Handles both A and AAAA DNS records with automatic PTR record generation
• 🎯 Smart Lease Management - Automatically adds, updates, and removes DNS entries based on lease state
• 🔌 Flexible Unbound Integration - Supports local and remote Unbound servers with custom config files
• 📝 Comprehensive Logging - Configurable log levels for debugging and monitoring
• ✅ Well Tested - 91% code coverage with 33 passing tests
  • Coverage badge above powered by Codecov (uploaded from GitHub Actions)

How It Works

1. Monitors a directory containing JSON lease files (typically from SLAAC or DHCP services)
2. Extracts hostname and IP address information from lease files
3. Generates DNS records (AAAA/A and PTR) for each active lease
4. Synchronizes with Unbound DNS server using unbound-control
5. Updates DNS records when leases change or expire

DNS Record Generation

For each lease, the service creates:

• AAAA record (or A for IPv4): Maps hostname to IP address
  • Example: test-host.lan IN AAAA 2001:db8::1
• PTR record: Maps IP address back to hostname
  • Example: 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa PTR test-host.lan

Installation

From Source

git clone https://github.com/junior/json-leases-to-unbound.git
cd json-leases-to-unbound
pip install -e .

Using pip (when published)

pip install json-leases-to-unbound

Usage

Command Line

json-leases-to-unbound [OPTIONS]

Options

Option	Default	Description
--log-level	INFO	Logging level: DEBUG, INFO, WARNING, ERROR, CRITICAL
--source	/run/slaac-resolver/	Source directory containing JSON lease files
--domain	lan	Default domain suffix for hostnames
--unbound-server	None	Remote Unbound server (IP:port)
--config-file	None	Path to Unbound config file

Examples

Monitor default directory with INFO logging:

json-leases-to-unbound

Monitor custom directory with debug logging:

json-leases-to-unbound --source /var/lib/dhcp/leases --log-level DEBUG

Use custom domain:

json-leases-to-unbound --domain home.local

Connect to remote Unbound server:

json-leases-to-unbound --unbound-server 192.168.1.1:8953

Use custom Unbound config:

json-leases-to-unbound --config-file /etc/unbound/unbound.conf

As a Python Module

from json_leases_to_unbound import main

main(
    log_level='INFO',
    source='/run/slaac-resolver/',
    domain='lan',
    unbound_server=None,
    config_file=None
)

JSON Lease File Format

The service expects JSON files with the following structure:

[
  {
    "Address": [8193, 3512, 0, 0, 0, 0, 0, 1],
    "AddressType": "IPv6",
    "Hostname": "test-host",
    "Expire": "2025-12-31T23:59:59Z"
  },
  {
    "Address": [192, 168, 1, 100],
    "AddressType": "IPv4",
    "Hostname": "another-host",
    "Expire": "2025-12-31T23:59:59Z"
  }
]

Field Descriptions

• Address: Array of integers representing the IP address
  • IPv6: 8 elements (e.g., [8193, 3512, 0, 0, 0, 0, 0, 1] → 2001:db8::1)
  • IPv4: 4 elements (e.g., [192, 168, 1, 100] → 192.168.1.100)
• AddressType: String indicating address type ("IPv4" or "IPv6")
• Hostname: String hostname for DNS entry
• Expire: ISO 8601 timestamp for lease expiration

Requirements

System Requirements

• Python 3.8 or higher
• unbound-control binary (part of Unbound DNS server)
• Appropriate permissions to execute unbound-control

Python Dependencies

• watchdog>=2.1.9,<3.0 - Filesystem monitoring

Development/Testing Dependencies

• pytest>=7.0.0
• pytest-mock>=3.10.0
• pytest-cov>=4.0.0

Development

Setting Up Development Environment

# Clone the repository
git clone https://github.com/junior/json-leases-to-unbound.git
cd json-leases-to-unbound

# Create virtual environment
python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate

# Install in editable mode with test dependencies
pip install -e ".[test]"

Running Tests

# Run all tests
pytest

# Run with coverage report
pytest --cov=json_leases_to_unbound --cov-report=html

# Run specific test file
pytest tests/test_core.py

# Run with verbose output
pytest -v

See TESTING.md for detailed testing documentation.

Project Structure

json-leases-to-unbound/
├── json_leases_to_unbound/
│   ├── __init__.py          # Package initialization
│   ├── __main__.py          # Entry point for python -m
│   ├── cli.py               # Command-line interface
│   └── core.py              # Core functionality
├── tests/
│   ├── __init__.py
│   ├── conftest.py          # Pytest fixtures
│   ├── test_cli.py          # CLI tests
│   ├── test_core.py         # Core functionality tests
│   └── README.md            # Testing documentation
├── pyproject.toml           # Project metadata and build config
├── requirements.txt         # Dependencies
├── README.md                # This file
└── TESTING.md              # Testing guide

How It Works Internally

Monitoring Process

1. Initial Scan: Processes all existing lease files in the source directory
2. Event Loop: Watches for filesystem events (create, modify, delete)
3. Change Detection: Compares new lease data with active leases in memory
4. DNS Updates: Generates and applies appropriate unbound-control commands

Lease State Management

The service maintains an in-memory cache of active leases keyed by filename and hostname. When changes are detected:

• New Lease: Adds DNS records to Unbound
• Modified Lease: Removes old records and adds new ones
• Deleted File: Removes all DNS records associated with that file
• Expired/Missing Lease: Removes DNS records for leases no longer in file

Unbound Control Integration

The service discovers the unbound-control binary automatically in common locations:

• /usr/sbin/unbound-control
• /usr/bin/unbound-control
• /usr/local/sbin/unbound-control
• Any location in PATH

Commands used:

• unbound-control local_datas - Add DNS records
• unbound-control local_datas_remove - Remove DNS records

Use Cases

SLAAC (Stateless Address Autoconfiguration)

Monitor IPv6 SLAAC leases and provide DNS resolution for auto-configured addresses:

json-leases-to-unbound --source /run/slaac-resolver/ --domain lan

DHCPv4/DHCPv6 Integration

Integrate with DHCP servers that export lease information as JSON:

json-leases-to-unbound --source /var/lib/dhcp/leases/ --domain home.local

Multi-Site DNS Management

Connect to remote Unbound servers for centralized DNS management:

json-leases-to-unbound \
  --source /var/lib/leases/ \
  --unbound-server 10.0.0.1:8953 \
  --domain site1.internal

Troubleshooting

Service Not Finding unbound-control

Ensure unbound-control is installed and in PATH:

which unbound-control

If not found, install Unbound:

# Debian/Ubuntu
sudo apt-get install unbound

# Fedora/RHEL
sudo dnf install unbound

# macOS
brew install unbound

Permission Denied Errors

Ensure the user running the service has permissions to:

• Read the source lease directory
• Execute unbound-control
• Access Unbound's control socket (typically /var/run/unbound/unbound.ctl)

You may need to add the user to the appropriate group:

sudo usermod -a -G unbound your-username

Lease Files Not Being Processed

Check log output with DEBUG level:

json-leases-to-unbound --log-level DEBUG --source /your/path

Verify JSON file format matches the expected structure.

DNS Records Not Appearing

Test unbound-control manually:

# Add a test record
echo "test.lan IN A 192.168.1.100" | sudo unbound-control local_datas

# Query the record
dig @localhost test.lan

# Remove the record
echo "test.lan IN A 192.168.1.100" | sudo unbound-control local_datas_remove

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Development Workflow

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes
4. Run tests (pytest)
5. Commit your changes (git commit -m 'Add amazing feature')
6. Push to the branch (git push origin feature/amazing-feature)
7. Open a Pull Request

Code Style

• Follow PEP 8 guidelines
• Add tests for new functionality
• Update documentation as needed
• Maintain or improve code coverage

License

MIT License - see LICENSE file for details

Author

Junior - [e-mail]

Links

• Repository: https://github.com/junior/json-leases-to-unbound
• Issues: https://github.com/junior/json-leases-to-unbound/issues
• Testing Guide: TESTING.md
• Test Documentation: tests/README.md

Acknowledgments

• Built with watchdog for filesystem monitoring
• Integrates with Unbound DNS