orin-nano-env-setup/docs/impl/reports/MOSQUITTO.md

type, date

type	date
report	2026-10-12

Mosquitto: the bus on the car Orin

The message bus (project-yukart decision 4), installed on the car unit.

Install

sudo apt-get install mosquitto mosquitto-clients     # 2.0.11-1ubuntu1.2 on Ubuntu 22.04

/etc/mosquitto/conf.d/yukart.conf:

# Yukart bus. Local only: displays reach it through svc-gw, never directly.
listener 1883 127.0.0.1
allow_anonymous true

systemctl enable --now mosquitto. It listens on 127.0.0.1:1883 only, so anonymous access is local access; nothing on the LAN, the tailnet or LTE can reach it.

Behaviour worth knowing

• Retained messages survive a reboot. Ubuntu's mosquitto.conf sets persistence true (/var/lib/mosquitto/), so after a reboot the broker hands out the last values from before it. svc-gw therefore treats a value known only from a retained copy as stale until a live one arrives.
• Units that use the broker order themselves After=mosquitto.service and nothing else, and reconnect by themselves when it restarts.
• Startup tier 1 (project-yukart docs/ORIN-RUNTIME.md).

First use

orin-status (svc-core) publishes the Orin's health on yukart/host/<signal> once a second; svc-gw subscribes and serves it to the tablet. Watching it:

mosquitto_sub -v -t 'yukart/#'

Not checked yet

• Throughput at raw CAN rates (yukart/can/raw, ~1000–3000 frames/s).