# x1208-exporter

One-shot Prometheus textfile exporter for the Geekworm X1208 UPS HAT on Raspberry Pi 5.

Reads:

- GPIO 6 (PLD) — `1` = AC plugged in, `0` = on battery.
- I2C `0x36` (MAX17040 fuel gauge) — battery voltage and state of charge.

Writes `/var/lib/node-exporter/textfiles/x1208.prom` atomically. node-exporter's
textfile collector serves it at scrape time.

## Metrics

| Name                            | Type  | Description                                  |
| ------------------------------- | ----- | -------------------------------------------- |
| `rpi_ups_ac_power`              | gauge | `1` = AC present, `0` = on battery           |
| `rpi_ups_voltage_volts`         | gauge | Battery cell voltage                         |
| `rpi_ups_battery_percent`       | gauge | State of charge (0–100)                      |
| `rpi_ups_last_update_seconds`   | gauge | Unix timestamp of last exporter run         |

## Deploy

```bash
just deploy
```

Builds the arm64 binary, scps to `rpi`, installs systemd units, starts the timer.

## Verify

```bash
just run-once   # forces one read, prints the prom file
just logs       # journalctl tail
```

## How node-exporter picks it up

The `monitoring` compose stack on the Pi must mount the textfile dir and pass
the flag to node-exporter:

```yaml
node-exporter:
  volumes:
    - /var/lib/node-exporter/textfiles:/textfiles:ro
  command:
    - '--collector.textfile.directory=/textfiles'
    # ...existing flags
```