MCDDNS

Mike Conigliaro's industrial-strength Dynamic Domain Name System client

Features

• Extensible plugin-oriented architecture with a simple API
  • Address providers are responsible for obtaining an address
  • DNS providers are responsible for managing a DNS record
• Resilient against network and endpoint failures
  • Built-in result validation for address providers
  • Use multiple address providers (keep trying until one succeeds)
  • Optional retry with Fibonacci backoff
  • Cron mode (prevents email flood if your Internet connections goes down)
• Detailed logging
• Dry-run mode (shows what will happen without changing anything)

Built-In Providers

Address Providers

• aws.CheckIP: Obtains a public IPv4 address via Amazon Web Services
• dyn.CheckIP: Obtains a public IPv4 address via Dyn
• google.CheckIP: Obtains a public IPv4 address via Google Domains
• ipify.IPv4: Obtains a public IPv4 address via ipify
• ipify.IPv6: Obtains an IPv6 address via ipify

DNS Providers

• aws.Route53: Manages records in Amazon Route53

Installation

pip install mcddns

Running the Application

mcddns <dns_provider> <fqdn> [options]

Use --help to see available options.

Development

Getting Started

poetry install
poetry shell
...

Running Tests

pytest

Writing Providers

A provider is any class that inherits from AddressProvider or DNSProvider. In production mode, Python modules/packages prefixed with mcddns_ will automatically be imported from the following locations:

1. $XDG_CONFIG_HOME/mcddns/provider
2. /etc/mcddns/provider
3. sys.path

Example: If you create a file at $XDG_CONFIG_HOME/mcddns/provider/mcddns_foo.py with a class named Bar that inherits from one of the Provider subclasses, your module can be referenced (e.g. in command-line options) as foo.Bar.

Provider Methods

Each provider type has a set of methods that will be called in a particular order. Note that some of these methods are expected to return a specific value in order to progress to the next step.

All Providers

1. options_pre(parser): Runs before option parsing. Use this method to add your own provider-specific command line arguments (See: argparse).
2. options_post(parser, options): Runs after option parsing. Use this method to do things with your provider-specific command line arguments.

Address Providers

1. fetch(options): Fetches and returns an IP address, hostname, etc.
2. validate(options, address): Returns True if the address is valid and False otherwise

DNS Providers

1. check(options, address): Returns True if a DNS update is required and False otherwise
2. update(options, address): Returns True if a DNS update was successful and False otherwise

Examples

I'll write more documentation if people are interested, but for now, see the examples at mcddns/provider and tests/provider.

Releases

1. Bump version in pyproject.toml
2. Update CHANGELOG.md
3. Run make release

To Do

• Add tests for built-in providers