nemo-mqtt-bridge 2.1.1

MQTT integration plugin for NEMO tool usage events

NEMO_mqtt_bridge

Knowing a tool's status (interlock enabled or disabled) is critical in most labs using NEMO, but many setups only indicate this via NEMO itself or a simple LED. This project enables NEMO to send MQTT messages to displays on each tool, providing detailed, real-time status information such as current user, start time, and previous user.

The hardware, firmware, and broker code associated with this project can be found at: https://github.com/alexanderenrique/NEMO-Tool-Display

This is a Django plugin that publishes NEMO tool usage events to MQTT (tool enable/disable, tool saves). Uses PostgreSQL LISTEN/NOTIFY and a separate bridge process to keep broker connections out of Django.

Architecture

┌─────────────────┐    ┌──────────────────┐    ┌─────────────────────┐    ┌─────────────┐
│   Django NEMO   │───▶│   PostgreSQL     │───▶│ PostgreSQL–MQTT      │───▶│ MQTT Broker │
│  (signals)      │    │  (event queue)   │    │ Bridge (standalone)  │    │             │
└─────────────────┘    └──────────────────┘    └─────────────────────┘    └─────────────┘

• Django: Signal handlers (Tool save, UsageEvent) insert into MQTTEventQueue and use pg_notify to wake the bridge.
• Bridge: Separate process runs python -m NEMO_mqtt_bridge.postgres_mqtt_bridge; it LISTENs for notifications, fetches events, and publishes to the MQTT broker with QoS 1.
• Topics: nemo/tools/{id}/enabled, nemo/tools/{id}/disabled

Configuration is stored in Django (e.g. /customization/mqtt/) and loaded by the bridge on each connection.

Installation

Prerequisites: Python 3.8+, Django 3.2+, NEMO-CE 4.0+, MQTT broker (e.g. Mosquitto), PostgreSQL 12+ (NEMO's database; 15, 16, 17, 18 tested). The plugin uses the same PostgreSQL database as NEMO; no Redis required.

Simplified deployment: The plugin package is NEMO_mqtt_bridge. Add 'NEMO_mqtt_bridge' to INSTALLED_APPS, then run python manage.py setup_nemo_integration (use --write-urls to add the URL include to NEMO/urls.py) and python manage.py migrate NEMO_mqtt_bridge.

From PyPI (recommended)

pip install nemo-mqtt-bridge
cd /path/to/your/nemo-ce
# Add 'NEMO_mqtt_bridge' to INSTALLED_APPS in your settings (see Manual below).
python manage.py setup_nemo_integration
python manage.py migrate NEMO_mqtt_bridge

Local / testing: The command above only prints integration steps (no file changes). Add NEMO_mqtt_bridge to INSTALLED_APPS and any logging config yourself. Use --write-urls to add the MQTT URL include to NEMO/urls.py.

Production with GitLab/Ansible: If your config is in version control and deployed by GitLab or Ansible, run with --gitlab so no files are changed on the server; the command will print the snippets to add to your repo:

python manage.py setup_nemo_integration --gitlab
# Add the printed snippets to your repo (INSTALLED_APPS and URLs; configure logging as needed for your environment), commit, and deploy. Then on the server:
python manage.py migrate NEMO_mqtt_bridge

Manual

1. pip install nemo-mqtt-bridge
2. Add 'NEMO_mqtt_bridge' to INSTALLED_APPS in your settings.
3. (Optional) If you use Django's LOGGING setting, add a NEMO_mqtt_bridge logger with your preferred level and handlers (e.g. DEBUG in dev/test, INFO or WARNING in production). What and how you log is installation-dependent.
4. Add path("mqtt/", include("NEMO_mqtt_bridge.urls")) to NEMO/urls.py (or run python manage.py setup_nemo_integration --write-urls). Skip this step for Docker/pip installs—NEMO auto-includes plugin URLs (see Plugin URLs).
5. Run python manage.py migrate NEMO_mqtt_bridge.

After install

1. Configure: Open /customization/mqtt/ in NEMO, set broker host/port (and auth if needed), enable the config.
2. Start NEMO (e.g. python manage.py runserver). With the default AUTO mode, the plugin uses the PostgreSQL–MQTT bridge and an embedded MQTT broker (mqttools, pure Python) for development. No separate broker binary required.

Production: Use EXTERNAL mode so the plugin does not start or kill brokers. Set NEMO_MQTT_BRIDGE_AUTO_START=0 (env) or NEMO_MQTT_BRIDGE_AUTO_START = False in Django settings. Then start the MQTT broker yourself, and run the bridge separately (e.g. python -m NEMO_mqtt_bridge.postgres_mqtt_bridge or as a systemd service).

Docker: You can run in AUTO mode with the embedded broker (no extra container) by default. The plugin uses mqttools (pure Python) as an in-process MQTT broker—no mosquitto binary needed. To use an external broker instead, set NEMO_MQTT_BRIDGE_AUTO_START=0 and point NEMO's MQTT config to your broker (e.g. broker_host=mqtt if using a service named mqtt in docker-compose).

Plugin URLs

The plugin exposes two URLs:

URL	Purpose
/mqtt_monitor/	Web dashboard: event stream from the queue (last 100 events), auto-refreshes every 3 seconds
/mqtt_monitor/api/	JSON API: returns recent events and bridge status for the monitor page

Where to find them depends on how NEMO loads the plugin:

• Docker / pip-installed NEMO: NEMO auto-includes URLs from apps whose names start with NEMO. The plugin is mounted at the root, so use /mqtt_monitor/ and /mqtt_monitor/api/. No manual URL config needed.
• Source install with --write-urls: If you add path("mqtt/", include("NEMO_mqtt_bridge.urls")) to NEMO/urls.py, the URLs are under /mqtt/: /mqtt/mqtt_monitor/ and /mqtt/mqtt_monitor/api/.

Both paths require login. If you get a 404, check which URL scheme your NEMO uses (auto-include vs manual).

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• Monitoring: Event stream at /mqtt_monitor/ (Docker) or /mqtt/mqtt_monitor/ (manual URL include); CLI tools in NEMO_mqtt_bridge.monitoring (see src/NEMO_mqtt_bridge/monitoring/README.md).
• HMAC: Optional payload signing
• License: MIT. Issues · Discussions