# brewpi Pi deployment notes

`config.json` is gitignored (`.gitignore:6`) - it's generated per-deployment
from `config-real.json.tpl`/`config-sim.json.tpl`, not tracked in git, so
notes about its actual on-Pi content have to live here instead.

## Heater/Stirrer `port` should use `/dev/serial/by-id/...`, not `/dev/ttyUSB0`/`/dev/ttyACM0`

Found 2026-07-03: unplugging the Hendi mid-brew (to test the connect/
disconnect feature, and the crash-recovery fix that followed) caused both
USB-serial adapters to renumber on replug - `/dev/ttyUSB0` became
`/dev/ttyUSB1`, `/dev/ttyACM0` became `/dev/ttyACM1`. `config.json` still
pointed at the old raw device paths, so a plain reconnect kept failing
(wrong port, not a code bug) until `config.json` was updated to the stable
`/dev/serial/by-id/...` symlinks udev already provides on this Pi:

```
Heater.port:  /dev/serial/by-id/usb-JDI_Hendi-Control_AM3VLPVE-if00-port0
Stirrer.port: /dev/serial/by-id/usb-Pololu_Corporation_Pololu_Simple_High-Power_Motor_Controller_18v15_53FF-6F06-7277-5049-3950-0767-if00
```

Since raw `/dev/ttyUSB*`/`/dev/ttyACM*` numbering isn't stable across
replugs (and a real unplug is exactly the scenario the connect/disconnect
feature exists to handle gracefully), `config.json` should keep using the
by-id paths above rather than reverting to `/dev/ttyUSB0`/`/dev/ttyACM0`.

## Cleanup: `config.json.bak-20260703212821`

A timestamped backup (`config.json.bak-20260703212821`) was left next to
`config.json` on the Pi before the by-id edit above, in case it needed to
be reverted. It wasn't needed - safe to delete once this note has been
read: `rm /home/jens/brewpi/config.json.bak-20260703212821`.