heartbeat/README.md

Heartbeat Daemon (hbd) ✅

A lightweight daemon that listens for UDP heartbeat messages and acts on them: keeps host state, optionally updates DNS records via nsupdate, forwards messages to WebSocket clients, and sends notifications (email, Pushover, Mattermost, Signal). It is a refactor of a previously monolithic script into a modular Python package (hbd).

---

📌 Features

• Receive and parse heartbeat datagrams (text or zlib-compressed) ✅
• Maintain host state and detect up/down transitions ✅
• Queue DNS updates via nsupdate and run them in a background thread ✅
• WebSocket API for live updates (hosts & messages) ✅
• Notification pipeline (email, Pushover, Mattermost, Signal) ✅
• Modular codebase suitable for unit testing and CI ✅

---

⚙️ Quickstart

Prerequisites:

• Python 3.10+ (project uses language features from recent Python)
• nsupdate (for DNS updates) if using dynamic DNS

Install dependencies (recommended into a venv):

python3 -m venv .venv
source .venv/bin/activate
python -m pip install --upgrade pip
python -m pip install -r requirements.txt
# for development/testing tools
python -m pip install -r requirements-dev.txt

Run the daemon (example):

# run with default config lookup (~/.hb.yaml)
PYTHONPATH=. hbd -c .hb.yaml -f -v

You can also run it directly via the package entrypoint after installation:

python -m hbd.cli -c /path/to/config.yaml

🐞 Debugging in VS Code

This repository includes a ready-to-use .vscode/launch.json with configurations to run or attach the VS Code debugger to hbd.

• Ensure the Python extension is installed and select the project .venv as the interpreter (bottom-left of VS Code).
• Use F5 and pick one of these configurations from the Run view:
  • Python: Run hbd (module) — runs hbd.cli as a module and sets PYTHONPATH to the workspace root (recommended).
  • Python: Run hbd with debugpy (listen) — launches debugpy and hbd together; useful when you want the process to listen for a debugger.
  • Python: Attach (localhost:5678) — attach the debugger to a running process started with debugpy.

To start hbd manually and wait for the debugger to attach, run:

PYTHONPATH=. python -m debugpy --listen 5678 --wait-for-client -m hbd.cli -c .hb.yaml -f -v

Set breakpoints in modules such as hbd/udp.py, hbd/dns.py, or hbd/server.py, and use the Attach configuration to connect. Use justMyCode: false if you need to step into third-party code.

---

🛠 Configuration

hbd reads YAML configuration (optional). If PyYAML is not installed, built-in defaults are used. Example configuration keys (see hbd/config.py):

• hb_port: UDP port to listen for heartbeats (default: 50003)
• hbd_port: internal control port (default: 50004)
• hbd_host: bind address for HTTP/WSS
• pickfile: path for persisted state
• logfile: path to log file
• logfmt: text or msg
• pushsrv: push service (pushover|mattermost|all)
• interval / grace: heartbeat timing configuration
• dyndomains: list of dyndomains to update via nsupdate
• nsupdate_bin: path to nsupdate binary

Example .hb.yaml (minimal):

hbd_host: 0.0.0.0
hbd_port: 50004
dyndomains:
  - example.com
nsupdate_bin: /usr/bin/nsupdate
pushsrv: pushover

Tip: config.DEFAULTS in hbd/config.py contains the canonical defaults and accepted configuration keys.

---

🔧 Architecture & Modules

• hbd.proto — serialization/deserialization of heartbeat messages (supports compressed payloads)
• hbd.udp — UDP parsing and handle_datagram implementation (main state machine)
• hbd.dns — create_nsupdate_payload, nsupdate, and a background DNS thread (start_dns_thread)
• hbd.notify — email and push notification helpers
• hbd.ws — WebSocket server and thread-safe broadcast helpers
• hbd.http — HTTP handler factory for the status UI/API
• hbd.utils — small utility helpers (shortname, dur, initlog)
• hbd.cli — CLI entrypoint and argument parsing
• hbd.server — async orchestration to run UDP/HTTP/WSS components

This modular layout makes the code easier to test and maintain.

---

🧪 Testing & Dev

Tests are implemented using unittest and additional tests rely on pytest if you prefer. To run tests locally without installing anything beyond the dev requirements:

# with project root on PYTHONPATH
PYTHONPATH=. python -m unittest discover -v
# or with pytest if installed
pytest -q

Developer tooling included:

• pyproject.toml — project metadata and dependencies
• requirements-dev.txt — dev/test dependencies
• tox.ini — convenience wrappers for running tests, lint, and mypy

To run linters and type checks locally:

# after installing dev deps
tox -e lint
tox -e mypy

---

🚀 Running in production

• Use your system service manager (systemd, launchd, etc.) to run hbd in the background.
• Ensure nsupdate and necessary credentials are available for dynamic DNS updates.
• Configure TLS for WSS if you enable secure websockets.

Note: The project contains a small example for obtaining DNS-verified certs (certbot with RFC2136) — see earlier commit history or ask me to re-add the example to this README if you want it documented here.

---

🤝 Contributing

Contributions welcome! Please:

1. Open an issue to discuss larger changes.
2. Create a topic branch and a clear PR.
3. Add tests for new features and run linters.
4. Keep changes focused and documented.

---

📜 License

This repository is licensed under the MIT license. See LICENSE for details.

---

If you'd like, I can also:

• add a GitHub Actions workflow that runs tests and lint on push/PR 🔁
• add a CONTRIBUTING.md template for PRs and code style 💬

Which one should I do next? ✨