380 lines
17 KiB
Markdown
380 lines
17 KiB
Markdown
# meta-core
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Standalone Go service that owns Redis, the leader-info file, the HTTP+SSE
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metadata surface, and a WebDAV file server for the MetaMesh dev/prod stack.
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## Overview
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meta-core runs as its own container (`metacore-app`). Other MetaMesh services
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(meta-sort, meta-fuse, meta-stremio, meta-dup, meta-share) discover it by
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reading `/meta-core/locks/kv-leader.info` and then call its HTTP API. Redis
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is not exposed outside the container — all metadata I/O is mediated by the
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HTTP API.
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### Key capabilities
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| Feature | Description |
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|---------|-------------|
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| **Leader gate** | Bash `flock` loop in `docker/leader-election.sh` only `exec`s supervisord on the winner. The Go binary therefore only ever runs as leader. |
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| **Redis owner** | Supervisord starts Redis with AOF + RDB persistence inside the container; meta-core connects to it on localhost. |
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| **HTTP API** | Typed REST surface (gorilla/mux) for metadata, KV browsing, snapshots, schema inference, mounts, watchers, services, and file access by CID. |
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| **SSE event streams** | `/api/events/files` and `/api/events/meta` mirror the underlying Redis Streams so external services never speak Redis. |
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| **WebDAV server** | `/webdav/*` exposes the `/files` volume (read+write) for cross-service file access. nginx in front of meta-core handles caching. |
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| **Service discovery** | File-based registry under `/meta-core/services/*.json` with heartbeat + dead-service cleanup. |
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| **File watcher / scanner** | Recursive scan + MidHash256 computation; emits events on `file:events`. |
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| **Mount management** | rclone-only mount manager (SMB rendered into `:smb:`, plus pre-defined remotes). Read-only by construction. |
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| **UUID-rooted storage** | Roots are UUIDv7 (Crockford Base32, ULID layout); CIDs are reverse-index aliases. Schema-version sentinel refuses to boot against stale data. |
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### Design characteristics
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- **Single-leader** — flock on a shared volume; no external consensus.
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- **HTTP-only externally** — Redis is bound to the container, never published.
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- **Schema-gated boot** — `EnsureSchemaVersion` aborts startup when the
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on-disk Redis layout predates the current build (alpha clean-wipe policy;
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see `docs/uuid-rooted-metadata.md`).
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- **Static binary** — CGO disabled, single Go binary plus a thin Alpine
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image with `redis-server`, `rclone`, nginx, and supervisord.
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## Architecture
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```
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┌──────────────────────────────────────────────────────────────────────────┐
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│ metacore-app (standalone container) │
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│ │
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│ supervisord │
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│ ├─ leader-election.sh (flock /meta-core/locks/kv-leader.lock, │
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│ │ writes kv-leader.info, exec supervisord) │
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│ ├─ redis-server (AOF + RDB on /meta-core/db/redis) │
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│ ├─ nginx (TLS termination, proxy_cache for /webdav) │
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│ ├─ rclone rcd (mount daemon, RC API) │
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│ ├─ mount-watcher.sh (rclone mount lifecycle) │
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│ └─ meta-core (Go) ─► HTTP API + SSE + WebDAV on :9000 │
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└──────────────────────────────────────────────────────────────────────────┘
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│
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┌──────────────────────┴──────────────────────┐
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│ /meta-core (shared volume) │
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│ locks/kv-leader.{lock,info} │
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│ db/redis/ │
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│ services/*.json │
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│ mounts/{mounts.json, errors/} │
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│ watchers.json │
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│ cache/ (nginx proxy_cache) │
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└─────────────────────────────────────────────┘
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▲
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┌──────────────────────────────┼────────────────────────────────┐
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│ │ │
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┌─────────────┐ ┌─────────────┐ ┌─────────────┐
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│ meta-sort │ │ meta-fuse │ │ meta-stremio│
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│ │ │ │ │ │
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│ reads │ HTTP+SSE │ reads │ HTTP+SSE │ reads │
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│ leader.info├──────────────►│ leader.info├───────────────►│ leader.info│
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└─────────────┘ └─────────────┘ └─────────────┘
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```
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## Quick start
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### Build
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```bash
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make build # build static binary to bin/meta-core
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make docker # build container image as meta-core:1.0.0 + :latest + :local
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make test # run Go unit tests
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```
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`make docker` tags the image as `:1.0.0`, `:latest`, **and** `:local`. The
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`:local` tag is the one every sub-stack docker-compose.yml references
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(meta-share 10-peer federation, meta-gateway dev stacks); without it the
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sub-stacks can't see a freshly-built image by name.
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> **Source-change → recreate.** `make docker` rebuilds and re-tags the
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> image, but **already-running containers stay on the old image SHA** —
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> `docker compose up -d` won't recreate them unless the compose file
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> itself changed. After a meta-core source change, force-recreate the
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> downstream containers so they pick up the new binary:
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>
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> ```bash
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> make docker
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> docker compose -f packages/meta-gateway/dev/docker-compose.yml \
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> up -d --force-recreate metagateway-generic-core
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> docker compose -f packages/meta-gateway/dev/docker-compose.torznab.yml \
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> up -d --force-recreate metagateway-torznab-core
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> docker compose -f packages/meta-share/dev/docker-compose.yml \
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> --profile share-10node up -d --force-recreate metashare-core metashare-core-test
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> ```
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>
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> The symptom of a missed recreate is missing API fields on `/urls`
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> (e.g. `webdavUrlInternal` absent → meta-gateway's
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> `store_poster_for_record` silently fails and torznab posters never
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> land). Audit recipe:
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>
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> ```bash
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> docker inspect meta-core:local --format '{{.Id}}' # fresh SHA
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> docker ps --filter ancestor=meta-core:local --format '{{.Names}}'
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> # any container whose Image SHA doesn't match the fresh SHA needs --force-recreate.
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> ```
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### Dev container
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In the MetaMesh dev stack, the container is brought up by `dev/docker-compose.yml`:
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```bash
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cd dev && ./scripts/start.sh
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```
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The user-facing URL is `https://metacore-dev.localhost:8083`; the direct-backend
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HTTP port (no auth, bypasses Caddy) is `http://localhost:18083`.
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## Configuration
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Environment variables consumed by `internal/config/config.go`:
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| Variable | Default | Description |
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|---|---|---|
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| `META_CORE_PATH` | `/meta-core` | Shared volume root (locks, db, services, mounts, cache). |
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| `FILES_PATH` | `/files` | Files volume root. |
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| `SERVICE_NAME` | `meta-core` | Identity in the service registry. |
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| `SERVICE_VERSION` | `1.0.0` | Reported via `/status` and registry. |
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| `API_PORT` | `8180` | External port baked into the leader-info `baseUrl`. |
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| `BASE_URL` | _empty_ | Overrides the constructed `baseUrl` if set (used for HTTPS perimeter). |
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| `REDIS_PORT` | `6379` | Local Redis port. |
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| `META_CORE_HTTP_PORT` | `9000` | Go HTTP+SSE+WebDAV port. |
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| `META_CORE_HTTP_HOST` | `0.0.0.0` | HTTP bind. |
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| `HEALTH_CHECK_INTERVAL_MS` | `5000` | Internal health-loop cadence. |
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| `HEARTBEAT_INTERVAL_MS` | `30000` | Service registry heartbeat. |
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| `STALE_THRESHOLD_MS` | `60000` | Age past which a registry entry is marked stale. |
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| `CLEANUP_INTERVAL_MS` | `600000` | Dead-service cleaner cadence. |
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| `DEAD_SERVICE_THRESHOLD_MS` | `600000` | Age past which a stale entry is deleted. |
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| `WATCH_INTERVAL_MS` | `1000` | Watcher poll cadence. |
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| `DEBOUNCE_MS` | `30000` | File-event debounce window. |
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| `ENABLE_FILE_WATCHER` | `true` | Disable to suppress the in-process watcher entirely. |
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Note: there is no `META_CORE_REDIS_PORT`, no `META_CORE_SERVICE_NAME`, and
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no `META_CORE_LEADER_TIMEOUT`. The Redis URL is discovered locally; service
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identity uses `SERVICE_NAME`; leader timeout is governed by the bash flock
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retry interval (`ELECTION_RETRY_SECS`, default `5`).
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## API reference
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All endpoints below are served by `internal/api/server.go`. Examples assume
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the in-container Go port `:9000`; from the host use
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`https://metacore-dev.localhost:8083` (Caddy) or `http://localhost:18083`
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(debug-direct).
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### Health, leader, URLs
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```bash
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GET /health # storage + role
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GET /status # version, uptime, etc.
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GET /leader # current leader info (hostname, PID, timestamps)
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GET /urls # baseUrl, apiUrl, webdavUrl, webdavUrlInternal (redisUrl is intentionally empty)
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GET /services # registered services + heartbeats
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GET /api/services # alias for /services
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GET /services/{name} # one service
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GET /services/cleanup/stats
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```
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### Metadata — primary surface
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These are the routes other services use. `{hash}` may be a UUID root or
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any registered CID alias; CID aliases resolve to the underlying UUID
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before reads/writes (`internal/storage/cid_resolution.go`).
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```bash
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GET /meta # list of root IDs
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GET /meta/{hash} # full document (flat keys → nested JSON)
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PUT /meta/{hash} # replace document
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PATCH /meta/{hash} # merge into document
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DELETE /meta/{hash} # delete root + all CID aliases
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GET /meta/{hash}/{key...} # single property (key may contain "/")
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PUT /meta/{hash}/{key...} # set single property
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DELETE /meta/{hash}/{key...} # delete single property
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POST /meta/{hash}/_add/{key...} # add value to set-valued property
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```
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CID-addressed access (public; auth-bypassed in the Caddy perimeter):
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```bash
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GET /api/meta/{cid} # resolve CID → metadata document
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GET /api/file/{cid}/info # CID resolution metadata
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GET /file/{cid} # serve file bytes (range-aware)
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POST /file/cid # compute CID for an uploaded file
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HEAD /data/{hash} # existence + size
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GET /data/{hash}/path # absolute path on /files
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```
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(There is no `/data/{hash}/stream`; bulk reads go through `/webdav/*` or
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the `/file/{cid}` reverse-lookup path.)
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### Editor / KV browser surface
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```bash
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GET /api/metadata/hash-ids
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GET /api/metadata/list
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POST /api/metadata/search
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POST /api/metadata/batch
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POST /api/metadata/clear
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GET /api/metadata/{hashId}
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PUT /api/metadata/{hashId}
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DELETE /api/metadata/{hashId}
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GET /api/metadata/{hashId}/property
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PUT /api/metadata/{hashId}/property
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GET /api/kv/info
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GET /api/kv/keys
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GET /api/kv/tree
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GET /api/kv/search
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GET /api/kv/find
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GET /api/kv/value
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PUT /api/kv/value
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DELETE /api/kv/value
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GET /api/kv/key/{key...}
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GET /api/schema
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POST /api/schema/rescan
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GET /api/snapshot/export
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POST /api/snapshot/import
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POST /api/snapshot/wipe
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```
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### SSE event streams
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The HTTP-mirror of the Redis Streams. External services never read Redis
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directly — they subscribe here with `Last-Event-ID` for resume. See
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[`docs/api-mediated-access.md`](docs/api-mediated-access.md) for the wire
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contract (one event per stream entry, opaque IDs, heartbeats, gap
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signalling).
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```bash
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GET /api/events/files # file:events stream (watcher events)
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GET /api/events/meta # meta:events stream (metadata mutations)
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```
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### Mounts
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```bash
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GET /api/mounts
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POST /api/mounts
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GET /api/mounts/{id}
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PUT /api/mounts/{id} # also PATCH
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DELETE /api/mounts/{id}
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POST /api/mounts/{id}/mount
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POST /api/mounts/{id}/unmount
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POST /api/mounts/{id}/safe-unmount
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POST /api/mounts/{id}/scan
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GET /api/mounts/rclone/remotes
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```
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### Watchers
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```bash
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GET /api/watchers
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POST /api/watchers
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GET /api/watchers/{id}
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PUT /api/watchers/{id}
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DELETE /api/watchers/{id}
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POST /api/watchers/{id}/scan
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POST /api/watchers/{id}/reset
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POST /api/watchers/scan-all
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POST /api/watchers/reset-all
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```
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The legacy `/api/scan/trigger` and `/api/scan/status` still respond but
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return a deprecation pointer at the `/api/watchers/*` routes
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(`internal/watcher/handlers.go:32-33`).
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### Admin / WebDAV
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```bash
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POST /api/admin/migrate-dual-roots # reunify stranded midhash-rooted entries
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POST /api/admin/sweep-literature-echoes[?apply=true]
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# strip query echoes off literature cards: anilistid on site cards,
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# workcid/chapterNumber/volumeNumber/chapterStart/chapterEnd on any card.
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# Dry-run unless apply=true; returns {dryRun, planned, fixed, byKey}
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GET/PUT/DELETE /webdav/... # mounted on /files
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```
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No `/metrics` endpoint is exposed; observability is via container logs and
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the `/health` / `/status` JSON.
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## Leader gate
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Leader election is a bash flock loop in `docker/leader-election.sh`, not a
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Go-level state machine. When `flock` succeeds on `kv-leader.lock`, the
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script writes the leader API URL to `kv-leader.info` and `exec`s
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supervisord. When the process tree dies, the kernel releases the lock and
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any standby instance can take over. There is no follower path inside the
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Go binary — there is no `OnBecomeLeader` / `OnBecomeFollower` callback API.
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`kv-leader.info` is a single plaintext line containing the API base URL:
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```
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http://10.0.1.50:9000
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```
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Other services read this file, then call `GET /urls` for full discovery.
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The dev compose runs a single `metacore-app`; the flock primitive is
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retained as a correctness anchor (one process owns Redis and the
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writable state under `/meta-core`), not as live failover.
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## Metadata storage shape (one-line summary)
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Roots are opaque UUIDv7 strings; every property is a separate Redis
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STRING at `file:<uuid>/<property>`; every known CID for a file is a
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reverse-index entry `cid:<algorithm>:<value> → <uuid>`. Full details in
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[`docs/metadata-storage-structure.md`](docs/metadata-storage-structure.md)
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and design rationale in [`docs/uuid-rooted-metadata.md`](docs/uuid-rooted-metadata.md).
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The authoritative registry of field semantics and value formats lives in
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the repo-root [`METADATA_KEYS.md`](../../METADATA_KEYS.md).
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## Internal packages
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| Package | Purpose |
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|---------|---------|
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| `cmd/meta-core` | Entry point; Redis connect + schema sentinel + service wiring. |
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| `internal/config` | Env-driven configuration, path helpers. |
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| `internal/leader` | `LeaderInfoProvider` (builds the leader info from local hostname/IP/config; no election logic). |
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| `internal/storage` | Redis wrapper (`client.go`), UUIDv7 minting (`uuid.go`), CID reverse index (`cid_resolution.go`), schema sentinel (`schema_version.go`), dual-root migration (`dual_root_migration.go`). |
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| `internal/cid` | CID parsing + algorithm ranking for canonical-CID selection. |
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| `internal/discovery` | Service registry + dead-service cleaner. |
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| `internal/events` | Keyspace-notification → `meta:events` stream publisher (`meta_publisher.go`). |
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| `internal/api` | HTTP server + all handlers + SSE event endpoints. |
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| `internal/schema` | Live per-field schema indexer (consumes `meta:events`). |
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| `internal/snapshot` | Snapshot export / import / wipe. |
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| `internal/watcher` | File system scanner, MidHash256 computation, dispatcher, state registry. |
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| `internal/watchers` | Polling-based watcher configurations (manager + poller + handlers). |
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| `internal/mounts` | rclone mount manager, lifecycle handlers, stats poller. |
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| `internal/webdav` | WebDAV handler (mounted at `/webdav/*`; nginx handles caching upstream). |
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### Startup sequence
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```
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1. Load configuration from environment
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2. Build LeaderInfoProvider (no election — the bash gate already won)
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3. Connect to local Redis (retry up to 30× / 1s)
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4. EnsureSchemaVersion — abort if the existing Redis layout is stale
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5. Start service discovery + dead-service cleaner
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6. Construct API server (initialises watcher, mounts, WebDAV)
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7. Start API server; on first connect, start MetaPublisher + schema Indexer
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and republish existing metadata onto meta:events
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8. Wait for SIGINT/SIGTERM, shutdown in reverse order
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```
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## Dependencies
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| Dependency | Purpose |
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|------------|---------|
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| `github.com/gorilla/mux` | HTTP router |
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| `github.com/redis/go-redis/v9` | Redis client |
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| `github.com/google/uuid` | UUIDv7 minting |
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| `golang.org/x/net` | WebDAV support |
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| Go stdlib | context, net/http, os, sync, syscall |
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Runtime requirements: Go 1.21+ at build time; the container ships Redis,
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rclone, nginx, and supervisord alongside the binary.
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## License
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Part of the MetaMesh project.
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