Frank
5c1006dda6
node-exporter is net=host, so its 192.168.0.143:9100 bind is a host bind, not a published port — the bridge-networked Prometheus container cannot reach its own host's LAN IP there (netavark DNATs published ports only). The node-dankclaw target has been red by construction since the observability cutover while the container reported healthy. Point it at host.containers.internal:9100 (netavark delivers that to the host LAN IP, where node-exporter listens) — the same rule frank-large and frank-small already use. node-dankserver is a different machine and keeps its LAN address. Update the cross-file contract test and the Targets table.
75 lines
4.4 KiB
Markdown
75 lines
4.4 KiB
Markdown
# Prometheus
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Prometheus collects metrics from every service on Dankclaw by scraping their `/metrics` endpoints, and feeds Grafana once a datasource exists. node-exporter supplies host metrics from both machines.
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**Host:** Dankclaw — **Vhost:** `prometheus.franksdank.cloud` (guarded: Anubis →
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Authentik; post-auth the Caddy vhost routes straight to `prometheus:9090`) —
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**Port:** 9090 (loopback) — **Docs:** https://prometheus.io/docs
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## Facts
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| Item | Value |
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|------|-------|
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| Image | `docker.io/prom/prometheus:latest` |
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| Published | `127.0.0.1:9090` → 9090, loopback only (see [[Observability]] → Exposure) |
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| Unit | `dankclaw/observability/quadlet/prometheus.container` → `prometheus.service` |
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| Config | `/opt/prometheus/config/prometheus.yml`, installed from `shared/prometheus/prometheus.yml` on every deploy |
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| Data | `/opt/prometheus/data` (TSDB) |
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| Retention | `--storage.tsdb.retention.time=30d` |
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| Alerting | 5 alert rules + 1 recording rule (`shared/prometheus/rules/llm-fleet.yml`), evaluated **and delivered** since 2026-09-17: the `alerting:` block ships to `alertmanager:9093` → Signal relay → signal-cli (see [[Alertmanager]]) |
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## Targets
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`shared/prometheus/prometheus.yml` is the source of truth; the deploy copies it into the container's `/etc/prometheus/`. In outline:
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| Job | Target | Why |
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|-----|--------|-----|
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| `prometheus` | `localhost:9090` | itself |
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| `node-dankclaw` | `host.containers.internal:9100` | host metrics from [[Node-Exporter]] — a net=host bind, so via the gateway (the LAN address is unreachable from this bridge container) |
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| `node-dankserver` | `192.168.0.235:9100` | host metrics from [[Node-Exporter]] — a different machine, so the LAN address works |
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| `grafana`, `loki` | `grafana:3000`, `loki:3100` | container names on the `dankclaw_default` network; both serve real `/metrics` |
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| `frank-medium` | `192.168.0.235:7770` | the LLM fleet — `vllm:` series; a different machine, so the LAN address works |
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| `frank-large`, `frank-small` | `host.containers.internal:7770`, `:7771` | the LLM fleet — `llamacpp:` series; same-host net=host binds, so via the gateway |
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**Three jobs read down, and they are not outages** (audited 2026-09-16):
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| Job | Target | Why it never reports up |
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|-----|--------|-------------------------|
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| `comfyui` | `comfyui:8188` | scrapes `/`, which is HTML — "unsupported Content-Type" |
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| `services` | `192.168.0.143:8081`, `:3005` | same: up/down intent, implemented as a scrape |
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| `gitea` | `192.168.0.143:3000/metrics` | Gitea's exporter is off until `[metrics] ENABLED = true` |
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A scrape cannot express "is this HTTP service answering?" — that is what a
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probe is for, and the remedy is the **blackbox exporter** in probe mode
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(`/probe?target=…&module=http_2xx`), which also gives the guarded vhosts a real
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uptime signal since Prometheus cannot solve an Anubis challenge itself. Until it
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is deployed, these three stay red for a structural reason: deleting them would
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hide a real service, and fixing them by publishing databases or enabling metrics
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would trade a wrong signal for a real exposure. Targets are `host:port`, never
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URLs.
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## Volumes
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| Container path | Host path |
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|----------------|-----------|
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| `/etc/prometheus` | `/opt/prometheus/config` |
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| `/prometheus` | `/opt/prometheus/data` |
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## Healthcheck
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Prometheus responds on `/-/healthy` with 200; the unit's health command is the same `wget --spider` the deploy waits on.
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## Gotchas
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- **Keep the node-exporter address in step with the unit.** `node-dankclaw` scrapes `192.168.0.143:9100`, which is exactly the LAN address `node-exporter.container` binds (`Network=host`, `--web.listen-address` twice). Change one without the other and host metrics stop with no error anywhere. The `tests/observability_quadlet.bats` seam pins the pairing.
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- The container name `prometheus` is what Caddy's post-auth handler proxies to, and `grafana`/`loki` are addressed by name here. Renaming a container breaks both silently.
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- Keep scrapes modest for a small homelab; too many targets bloat the TSDB.
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- Set a retention policy or the data volume grows without bound (30 days here).
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- The lifecycle endpoint is enabled (`--web.enable-lifecycle`), which is why this API must never be published beyond loopback.
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## See Also
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- [[Grafana]] — the dashboard frontend (datasource and LLM dashboard provisioned as code since 2026-09-16)
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- [[Node-Exporter]] — the host metrics source
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- [[Observability]] — the whole stack, including what is still unconfigured
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