Frank
e7f0d93c86
The docs-fact census wave re-read the live hosts and re-keyed every page it could: runtime/payload identities, ports, sizes, ledger figures, unit state, and the retirement banners that drifted as the fleet moved. The wave was interrupted mid-run, so this commit carries only what passed the integrity gates: every touched page parses (front matter or H1+status convention intact, balanced fences, no truncated tables, trailing newline), the docs_completeness and link-integrity seams are green, and bats is 384/384. Numbers that this session proved on live hosts are keyed to the measured value, not the page's earlier claim.
75 lines
5.8 KiB
Markdown
75 lines
5.8 KiB
Markdown
---
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type: reference
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description: "Alloy is Grafana's log and telemetry shipper."
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tags:
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- infrastructure
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timestamp: 2026-09-11
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---
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# Alloy
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Alloy is Grafana's log and telemetry shipper. It replaces Promtail (end of life as of 2026-03-02, https://grafana.com/docs/loki/latest/send-data/promtail/). It is wired to forward container and journal logs to Loki, and every unit in the path is healthy — but as of 2026-10-18 it is delivering **zero** log lines. See "Delivery state" below.
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**Host:** Dankclaw (one instance per host) — **Port:** 12345 (loopback) — **Docs:** https://grafana.com/docs/alloy/latest
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## Facts
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| Item | Value |
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|------|-------|
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| Image | `franksdank/alloy:latest` (local build: upstream + a static busybox for the healthcheck) |
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| Published | `127.0.0.1:12345` → 12345 (its own UI/health port) |
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| Unit | `dankclaw/observability/quadlet/alloy.container` → `alloy.service` |
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| Config | `shared/alloy/config.alloy`, installed to `/opt/alloy/config/config.alloy` on every deploy (`scripts/deploy-remote.sh:281-284`) |
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| Inputs | host journald socket, podman container logs, `/var/log` |
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| Output | `http://loki:3100/loki/api/v1/push` (`shared/alloy/config.alloy:13-17`) |
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| Successor to | Promtail (EOL 2026-03-02, https://grafana.com/docs/loki/latest/send-data/promtail/) |
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| Boot persistence | `Restart=always`/`RestartSec=10` + `WantedBy=default.target` (`dankclaw/observability/quadlet/alloy.container:58-63`); installed at `~/.config/containers/systemd/alloy.container`, reporting `generated` + `active` (`systemctl --user is-enabled|is-active alloy` 2026-10-18) |
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| Delivery | **Configured and healthy, currently delivering zero data** — see "Delivery state" |
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## Why Alloy and not Promtail
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Promtail reached end-of-life on 2026-03-02 and Grafana Labs directs new installs to Alloy. This stack uses Alloy from day one: no Promtail config or unit has ever existed in this repository (`git log -S promtail` over the whole history returns no commit that added one; the compose-era service of the same name was already Alloy — `dankclaw/observability/quadlet/alloy.container:6-7`).
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## Configuration
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`shared/alloy/config.alloy` is the source of truth:
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- Reads journald logs from the host's `/run/systemd/journal/socket`, labelled `job="systemd-journal"` (`shared/alloy/config.alloy:20-26`).
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- Reads container logs from two globs: `/var/lib/containers/storage/overlay-containers/*/userdata/ctr.log` (`job="podman"`) and `/var/log/containers/*.log` (`job="containers"`) (`config.alloy:29-35`).
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- Forwards everything to `http://loki:3100/loki/api/v1/push` by container name on `dankclaw_default` (`config.alloy:13-17`).
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## Volumes
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| Container path | Host path |
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|----------------|-----------|
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| `/etc/alloy` | `/opt/alloy/config` |
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| `/run/systemd/journal/socket` | host journald socket (read-only) |
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| `/var/log` | host logs (read-only) |
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| `/var/lib/containers` | podman storage (read-only) |
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## The UI port is published on purpose
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Alloy's UI listens on the container's own `127.0.0.1:12345` by default, and Alloy 1.x refuses to configure the `ui` service from a config block ("service ui does not support being configured", `shared/alloy/config.alloy:8-10`). Under compose that meant **no reachable health endpoint at all**: the homepage status card for alloy read `down` continuously and a deploy had nothing to wait on. The unit therefore passes `--server.http.listen-addr=0.0.0.0:12345` (`dankclaw/observability/quadlet/alloy.container:46`) and publishes `127.0.0.1:12345` (`alloy.container:47`, confirmed by `ss -ltnp` 2026-10-18) — same posture as the other three: reachable from the host and from Caddy's network, and from nothing off-host. Alloy has no authentication, which is exactly why it is not published wider. The homepage card probes that same loopback port (`shared/homepage/services.json:233`).
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## Delivery state (2026-10-18): healthy, shipping nothing
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The unit is `active`, the container reports `healthy`, the log says `Alloy is ready`, and the pipeline carries no data at all. Measured on 2026-10-18:
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- `curl -s http://127.0.0.1:12345/metrics` → `loki_source_journal_target_lines_total{component_id="loki.source.journal.journal"} 0` and `loki_source_file_files_active_total{component_id="loki.source.file.containers"} 0`. The journal source logs no error; the counter simply never moves. The journal files it would have to read through the `/var/log` bind are `root:systemd-journal 0640` with an ACL (`ls -l /var/log/journal/64a287d7…/` 2026-10-18).
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- Both file globs were refused at start (`journalctl --user -u alloy`, 2026-10-18T08:25:27Z), verbatim: `failed to create source, skipping … component_id=loki.source.file.containers error="failed to tail file, stat failed: stat /var/lib/containers/storage/overlay-containers/*/userdata/ctr.log: permission denied"` and the same message for `/var/log/containers/*.log: no such file or directory`.
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- Downstream that means Loki holds zero streams — `GET /loki/api/v1/labels` returns `{"status":"success"}` with no `data` — see [[Loki]].
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No fix is claimed here: the unit, the config and the push endpoint are all correct as written, and the gap is source-side access (and a Kubernetes-style glob that does not exist on this host). Anyone closing it should re-check the two counters above, not the health status — health is exactly what hides this failure mode.
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## Gotchas
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- The journald socket mount is required for journal scraping.
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- Container log paths differ between docker (`/var/lib/docker/containers`) and podman (`/var/lib/containers/storage/...`); point the config at the right one per host.
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- One Alloy per host; do not run a single instance that tries to reach both hosts' logs.
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- The unit `Wants=`/`After=` `loki.service`: without a reachable Loki the write client fails and the pipeline backs up.
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## See Also
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- [[Loki]] — the log backend
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- [[Observability]] — the full stack, including what is still unconfigured
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