Paul Payne
c67c06d8e6
- add static 'role' (authority|follower) to NodeConfig/CastleConfig, wired from castle.yaml through the registry to the mesh wire; civil pinned authority - castle-presence: TTL KV bucket each node renews (churn signal); delete-on-stop - castle-config: authority-gated get/put + change-watch SSE (follower reconcile hook hangs off it) - bound the NATS drain on stop() so shutdown can't hang - tests: role config/registry round-trip, wire round-trip, role write-gating Single-node verified; follower reconcile pending the second node.
238 lines
14 KiB
Markdown
238 lines
14 KiB
Markdown
# Fleet Mesh Plan — OpenBao + NATS
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**Status:** in progress on branch `feat/fleet-mesh-nats-openbao`.
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Phases 0–2 complete + single-node verified (live). Phases 3–4 pending (need 2nd node).
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## Context
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Castle's mesh today is a deliberately minimal, read-only gossip: each node
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publishes a secret-stripped `NodeRegistry` to Mosquitto MQTT (retained) + an
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online/offline LWT, and peers aggregate it into `MeshStateManager`. It is
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LAN-only, unauthenticated, carries no secrets, and does nothing with what it
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discovers beyond display.
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The goal is a **purpose-driven heterogeneous fleet** (media server, security
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appliance, TV, comms handler, AI gateway) where nodes come and go as *expected*:
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shared LAN-wide config + selected secrets, discoverability + presence, and
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binding **by purpose** (a consumer needs `media-index`, not a hostname) with
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**circuit-breakers** so churn degrades gracefully instead of hanging.
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Two adopted, genuinely-open components (see licensing analysis in chat history):
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- **NATS** (CNCF, Apache-2.0) — replaces Mosquitto as the mesh substrate and does
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three jobs in one: pub/sub, **JetStream KV** (shared config + registry), and
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**TTL keys as presence** (a provider's key vanishes on death → the breaker
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trip signal, no separate health plumbing).
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- **OpenBao** (Linux Foundation / OpenSSF, MPL-2.0, Vault fork) — the secret
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authority behind castle's existing `${secret:...}` mechanism.
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Design stance: **static single-writer `role` authority, no consensus** —
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availability comes from followers running cached local state, not failover.
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NATS single-node matches that topology. Consensus stays explicitly out of scope.
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## Architecture — planes → components → code seams
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| Plane | Component | Primary code seam (verified) |
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|-------|-----------|------------------------------|
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| Transport + KV + presence | NATS (`castle-nats`) | `castle-api/.../mqtt_client.py` (whole file), `main.py` lifespan 62-77, `config.py` Settings |
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| Shared config + registry + presence | NATS JetStream KV | `mesh.py` `MeshStateManager`; new KV buckets |
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| Secret authority | OpenBao (`castle-openbao`) | `core/.../config.py:307` `_read_secret` (single chokepoint), `castle-api/.../secrets.py` CRUD |
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| Binding-by-purpose + breaker | Caddy gateway | `generators/caddyfile.py` `compute_routes` (`remote` kind + ignored `remote_registries` are pre-stubbed), `deploy.py:509-540` `_target_url`/`_requires_env` (local-only today) |
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| Authority role | `NodeConfig.role` | `castle_core/registry.py` / `manifest.py` |
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## Phased plan
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Each phase is independently useful; the risky secret-transport work is last.
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### Phase 0 — Stand up the two services (no behavior change)
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- **`castle-nats`**: a `SystemdDeployment` + `RunContainer` (`nats:2` with
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JetStream `-js`), data volume `/data/castle/castle-nats`, `reach: internal`
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(`nats.<domain>`). Follow the container YAML shape in `docs/tcp-exposure.md`
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(postgres example). Replace the Mosquitto provisioning in `install.sh`
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(`setup_mqtt`, `seed_mosquitto_config`, image/port consts) with NATS — or
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better, promote it to a bootstrap deployment YAML (today the broker is only a
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shell-provisioned container, not a declared deployment).
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- **`castle-openbao`**: `RunContainer` (`openbao/openbao`), data volume, a file
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storage backend, `reach: internal`, **auto-unseal** (local transit/key) so the
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node boots unattended (Decision 2).
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### Phase 1 — NATS as the mesh transport (swap Mosquitto, behavior-preserving)
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- New `nats_client.py` (async-native `nats-py`) replacing `mqtt_client.py`.
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Registry → a **JetStream KV bucket `castle-registry`** keyed by hostname
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(KV last-value replaces MQTT retained). Presence → a **`castle-presence`**
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bucket with a per-node **TTL key** the node renews (replaces LWT + the 300s
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`STALE_TTL` poll; note `prune_stale` is currently uncalled).
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- Wire in `main.py` lifespan; rename `mqtt_*` → `nats_*` in `config.py` (keep
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`CASTLE_API_` prefix). `MeshStateManager` logic is reused; the KV **watch**
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callback drives `update_node`/`set_offline` — and because `nats-py` is
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asyncio-native, the `run_coroutine_threadsafe` cross-thread hop for
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`broadcast("mesh", …)` **goes away**.
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- **Preserve the secret-stripping invariant** from `_registry_to_json` (env /
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run_cmd / castle_root never on the wire).
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- Rename MQTT-named fields: `models.py` `MeshStatus` (217-226) + frontend
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`types/index.ts` (326-330), `MeshPanel.tsx`. Drop `paho-mqtt`; add `nats-py`.
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Keep zeroconf peer-advert for LAN discovery **and** support explicit NATS seed
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URLs for cross-network (Decision 1); drop the dangling unused `_mqtt._tcp`
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browse. Rewrite `test_mqtt.py` → `test_nats.py`.
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- Fixes a latent gap: today the registry is published **on-connect only** (no
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periodic/on-change republish). KV writes on `castle apply` fix this naturally.
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### Phase 2 — Shared config + presence via JetStream KV
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- Buckets: `castle-config` (shared LAN config, **authority-written only**),
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`castle-registry` (per-node), `castle-presence` (TTL liveness).
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- Add static **`role: authority | follower`** to `NodeConfig` (castle.yaml).
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Pin **`civil` = authority** (Decision 3); only the authority may write
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`castle-config`. Authority-down ⇒ shared state read-only, nodes serve cached.
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- Followers **watch** `castle-config` and reconcile via `castle apply`. Presence
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key renewal is the churn signal for Phase 3.
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### Phase 3 — Cross-node `requires` resolution + gateway binding + breaker (keystone)
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- Extend `_target_url`/`_requires_env` (`deploy.py:509-540`) to **fall through to
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the mesh registry** when a `ref` isn't satisfied locally (today it's
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local-only). The ref is already host-independent — this removes the
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"must be local" restriction, not adds a concept.
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- Produce the pre-stubbed **`remote` `GatewayRoute`**; thread `remote_registries`
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into `compute_routes` (currently accepted-but-ignored) and into the Caddyfile
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write at `deploy.py:157` (currently passed nothing). Binding = a **stable local
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subdomain route** the gateway re-targets to the remote node's URL — the program
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sees one unchanging URL.
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- **Circuit-breaker:** gate the remote route on the `castle-presence` key
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(regenerate + `_reload_gateway` when a provider appears/vanishes), backed by
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Caddy passive health (`fail_duration` / `lb_try_duration`) on the
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`reverse_proxy` line in `_host_matcher_block`. Consumer degraded-mode =
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fallback target or clean 503. (Also carry `health_url` into the registry —
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it's currently dropped on `manager: none` refs.)
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### Phase 4 — OpenBao as the secret backend (last; needs the security foundation)
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- Introduce a **`SecretBackend` seam** at the single read chokepoint
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`_read_secret` (`config.py:307`) + the `castle-api/.../secrets.py` writer:
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`FileSecretBackend` (default, unchanged) and `OpenBaoBackend`. `${secret:NAME}`
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syntax is untouched; backend selected in castle.yaml or by env.
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- Followers auth to OpenBao (token / AppRole); **need-to-know scoping** via
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per-deployment policies. Keep the file backend as fallback; migrate secrets in.
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### Cross-cutting prerequisite (gates Phase 4 + any cross-network)
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- **Transport hardening**: NATS TLS + nkey/user auth (replace Mosquitto's
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`allow_anonymous`); OpenBao TLS listener. No secret and no cross-network link
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moves until this is in. Cross-network overlay (e.g. Nebula) is orthogonal and
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layers under Caddy later.
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## Verification (per phase, end-to-end)
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- **P1:** bring up two nodes; confirm registry + presence propagate over NATS and
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the mesh view (`/mesh/status`, System Map) is identical to the MQTT behavior.
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- **P2:** write a key to `castle-config` on the authority; observe a follower
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watch fire and `castle apply` reconcile.
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- **P3:** define a service on node A that `requires` a ref provided on node B;
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confirm the gateway routes cross-node, then **kill node B** and confirm the
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consumer fails fast (curl returns the degraded 503, not a hang) and **recovers**
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when B returns.
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- **P4:** store a secret in OpenBao; confirm a service renders it via
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`EnvironmentFile=` / `--env-file`; then disable the file fallback and confirm
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it still resolves.
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## Progress
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### Phase 0 — DONE + verified (2026-07-07)
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Both services stood up **alongside** the live MQTT mesh (no cutover yet):
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- `castle-nats` (`nats:2`, JetStream) — deployment
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`~/.castle/deployments/services/castle-nats.yaml`, config
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`/data/castle/castle-nats/config/nats-server.conf`. Verified: container active,
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`/healthz` ok, JetStream enabled (`/jsz` shows store dir + limits), and a real
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**KV round-trip** — created `castle-registry` (put/get) and a TTL
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`castle-presence` bucket (the presence primitive). Test buckets cleaned up.
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- `castle-openbao` (`openbao/openbao:latest`, v2.5.5) — deployment
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`~/.castle/deployments/services/castle-openbao.yaml`, config
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`/data/castle/castle-openbao/config/openbao.hcl`. Verified: initialized (1
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share / threshold 1), unsealed, **KV-v2 secret put/get/delete** round-trip.
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Unseal key + root token stored as castle secrets `OPENBAO_UNSEAL_KEY` /
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`OPENBAO_ROOT_TOKEN`.
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**Consciously deferred (tracked):**
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1. **Auto-unseal on boot.** OpenBao is unsealed now but a container restart
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re-seals it. The manifest `SystemdSpec` has no `exec_start_post` hook, so
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proper boot-unseal wiring lands with Phase 4 (either a small manifest
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addition or a companion oneshot). Manual recovery: unseal with
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`OPENBAO_UNSEAL_KEY`.
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2. **`install.sh` bootstrap parity.** Fresh-install provisioning still seeds
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Mosquitto; adding NATS/OpenBao there (and retiring Mosquitto) is bootstrap-only
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(no runtime impact) and folds in with the Phase 1 cutover.
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### Phase 1 — DONE + single-node verified; live cutover done (2026-07-07)
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MQTT/Mosquitto transport replaced by NATS JetStream KV.
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- New `castle_api/mesh_wire.py` — transport-agnostic registry (de)serialization
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(moved out of `mqtt_client.py`; preserves the secret-stripping invariant).
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- New `castle_api/nats_client.py` — `CastleNATSClient`: connects, PUTs its
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registry to the `castle-registry` KV bucket, seeds from existing keys, watches
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for peer PUT/DELETE, heartbeats a re-PUT (crash liveness via the existing
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stale-TTL), and DELETEs its key on graceful stop (immediate peer-offline).
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Async-native → the paho cross-thread `run_coroutine_threadsafe` hop is gone.
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- `main.py` lifespan, `config.py` (`nats_enabled`/`nats_url`), `models.py`
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`MeshStatus` (`connected`/`nats_url`), `nodes.py` `/mesh/status` all rewired.
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- Frontend: `types/index.ts` `MeshStatus` + `MeshPanel.tsx` updated to the new
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fields. `mqtt_client.py` + `test_mqtt.py` deleted; `test_mesh_wire.py` added.
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`mdns.py` dead `_mqtt._tcp` broker-browse removed. `paho-mqtt` → `nats-py`.
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- **Live cutover:** `castle-api.yaml` env → `CASTLE_API_NATS_*`, `requires:
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castle-nats`; applied. castle-api healthy on NATS, `/mesh/status` connected,
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registry (9.7 KiB, 48 deployments) published to KV, **no secrets on the wire**.
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- Verification run: ruff clean; 89 api + 196 core tests pass; frontend `tsc`
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clean; runtime KV round-trip confirmed against the live `castle-nats`.
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**Pending second node:** two-node mesh-view parity (peer sees peer, offline on
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departure) — needs the second LAN node running the NATS-enabled castle-api
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pointed at civil's NATS (seed URL) or a clustered `castle-nats`. Revert path if
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needed: restore `CASTLE_API_MQTT_*` env — but note `mqtt_client.py` is deleted,
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so revert = `git checkout main -- castle-api` then re-apply. The old Mosquitto
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`mqtt` service is left running (dormant) as a safety net; retire it once the
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second node is proven on NATS.
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### Phase 2 — DONE + single-node verified + tested (2026-07-07)
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- **`role` field** on `NodeConfig` + `CastleConfig`, wired end-to-end:
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castle.yaml top-level `role:` → config → `_node_config` → registry.yaml →
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mesh wire. **`civil` pinned `role: authority`**; default `follower`.
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- **Presence** (`castle-presence`) — a TTL KV bucket each node renews on the
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heartbeat; expiry = the node is gone. Delete-on-stop for immediate departure.
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- **Shared config** (`castle-config`) — `get_shared_config` / `put_shared_config`
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(authority-gated: followers raise `PermissionError`), plus a watch loop that
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broadcasts a `config_changed` SSE (the follower `castle apply` reconcile hook
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hangs off this — inert on one node).
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- Hardened `stop()` to bound the NATS drain (can't hang systemd shutdown).
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- Verified live: all three buckets present, `civil=online` presence,
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`"role": "authority"` on the wire, authority write + follower-deny exercised
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against the running `castle-nats`.
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- **Tests added:** `core/tests/test_fleet_role.py` (role config load + registry
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round-trip), `castle-api/tests/test_nats_client.py` (role gating, hermetic),
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role round-trip in `test_mesh_wire.py`. Suites: **200 core + 93 api** pass.
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**Pending second node:** the follower-side reconcile (watch `castle-config` →
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`castle apply`) is wired as an SSE hook but only meaningful with a peer.
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## Decisions (resolved)
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1. **Discovery — both.** Keep mDNS for zero-config LAN peer discovery *and*
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support explicit NATS seed URLs so the mesh can span networks. mDNS is the
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convenience path on-LAN; seed URLs are the cross-network path. Client connects
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via seeds when present, falls back to mDNS-discovered peers on-LAN.
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2. **OpenBao unseal — auto for now.** Auto-unseal (local transit/key) so a home
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node boots unattended; designed so we can migrate to manual/stricter unseal
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later (a supported rekey/unseal-migration, not zero-effort but planned for).
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Keep the backend seam clean so the switch is config, not code.
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3. **Authority = `civil`.** `civil` (the acme node, `civil.payne.io`) is pinned
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as `role: authority`; all others are followers. **Confirmed:** when `civil` is
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down, shared config/secrets go **read-only** fleet-wide and every node keeps
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serving its own deployments from cached local state.
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4. **NATS — single server now, cluster-ready.** Run one `castle-nats` today
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(matches the single-writer authority). Clustering is deferred but must be a
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pure config addition (cluster/routes block + a few more nodes) — no re-architecture.
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