# Node-RED update logging for Grafana

This guide adds structured update-event logging to your existing Node-RED + Telegraf + Prometheus + Grafana stack without introducing Loki.

## Goal

Track and surface (in Grafana) the latest update attempts from Node-RED, including:

- when an update attempt started,
- target container/project,
- success/failure,
- optional failure reason,
- elapsed duration.

## 1) Add a reusable logger function in Node-RED

Create a **Function** node named `Build update log event` and use:

```javascript
const nowIso = new Date().toISOString();
const startedAt = msg.update_started_at || Date.now();
const durationMs = Math.max(0, Date.now() - startedAt);

const payload = msg.payload || {};
const labels = payload.labels || {};

const status = (msg.update_status || payload.status || "unknown").toString().toLowerCase();
const success = status === "success" ? 1 : 0;
const failed = status === "failed" ? 1 : 0;

msg.payload = {
  ts: nowIso,
  flow: "docker-updates",
  event: msg.update_event || "attempt",
  container: msg.container || labels.container || "unknown",
  project: labels.com_docker_compose_project || msg.project || "unknown",
  host: msg.host || "unknown",
  status,
  success,
  failed,
  duration_ms: durationMs,
  code: Number.isFinite(Number(payload.code)) ? Number(payload.code) : 0,
  error: (msg.update_error || payload.error || "").toString().slice(0, 300)
};

// one JSON line per event for file output
msg.payload = JSON.stringify(msg.payload);
return msg;
```

### Wiring recommendation

Use the same logger function in these branches:

- before a pull/update command (`update_status=started`, `update_event=attempt`),
- success path (`update_status=success`, `update_event=completed`),
- failure path (`update_status=failed`, `update_event=completed`, and include `msg.update_error`).

Then route each branch into a **File** node configured as:

- Filename: `/data/update-events.ndjson`
- Action: append to file
- Add newline: enabled

## 2) Make update state explicit in existing update flow

In your current update flow (already present in `flows.json`), add/change **Change** nodes around your shell/docker nodes:

- At update start:
  - `msg.update_started_at = $millis()`
  - `msg.update_status = "started"`
  - `msg.update_event = "attempt"`
- At success:
  - `msg.update_status = "success"`
  - `msg.update_event = "completed"`
- At failure:
  - `msg.update_status = "failed"`
  - `msg.update_event = "completed"`
  - `msg.update_error = msg.payload.stderr` (or equivalent error field)

## 3) Let Telegraf ingest Node-RED event logs

Append this to `monitoring/telegraf/telegraf.conf`:

```toml
[[inputs.tail]]
  files = ["/var/log/node-red/update-events.ndjson"]
  from_beginning = false
  name_override = "node_red_update_event"
  data_format = "json_v2"

  [[inputs.tail.json_v2]]
    measurement_name = "node_red_update_event"

    [[inputs.tail.json_v2.tag]]
      path = "flow"
    [[inputs.tail.json_v2.tag]]
      path = "event"
    [[inputs.tail.json_v2.tag]]
      path = "container"
    [[inputs.tail.json_v2.tag]]
      path = "project"
    [[inputs.tail.json_v2.tag]]
      path = "host"
    [[inputs.tail.json_v2.tag]]
      path = "status"

    [[inputs.tail.json_v2.field]]
      path = "success"
      type = "int"
    [[inputs.tail.json_v2.field]]
      path = "failed"
      type = "int"
    [[inputs.tail.json_v2.field]]
      path = "duration_ms"
      type = "int"
    [[inputs.tail.json_v2.field]]
      path = "code"
      type = "int"
```

And mount the Node-RED data directory into Telegraf (read-only) in `monitoring/prometheus/docker-compose.yml` under `telegraf.volumes`:

```yaml
      - ${PROJECT_ROOT}/monitoring/node-red/data:/var/log/node-red:ro
```

## 4) Prometheus scrape (already in place)

No Prometheus scrape change is required as long as it already scrapes Telegraf (`telegraf:9273`).

## 5) Grafana queries to start with

Use your Prometheus data source and try:

- Latest success/failure by container:
  - `last_over_time(node_red_update_event_success[24h])`
  - `last_over_time(node_red_update_event_failed[24h])`
- Failed updates in the last 24h:
  - `sum by (container, project) (increase(node_red_update_event_failed[24h]))`
- Average update duration in last 24h:
  - `avg by (container, project) (avg_over_time(node_red_update_event_duration_ms[24h]))`

Recommended panels:

- **Table**: container, project, status (last value), duration_ms (last value)
- **Time series**: failed count over time
- **Stat**: total failed updates in last 24h

## 6) Validation checklist

1. Trigger a known update path (including one failure if possible).
2. Check Node-RED log file:
   - `tail -n 20 monitoring/node-red/data/update-events.ndjson`
3. Check Telegraf metrics endpoint for `node_red_update_event_` metrics.
4. Confirm Grafana panel values match the latest Node-RED run.

## Optional next step

If you want searchable raw log text and richer log UX, add Loki + Promtail later. Keep this structured metrics path for high-signal alerting even after adding logs.