wtclaude
e2a58f3455
The rust-link sidecar: it owns the loopback listener the Oxide bridge plugin dials into, and serves the website a WebSocket feed plus store-backed reads. Protocol 1 is deliberately three frames — server.hello, ping/pong, and one correlated server.status — because phase 1's job is to get every seam working at once with almost nothing in them. What is load-bearing rather than incidental: * The plugin is the TCP client and this process owns the listener, so a Rust server opens no extra port. Loopback is the trust boundary on that link and there is no token on it; the website-facing surface is the opposite, with auth always on and a token generated and persisted on first start. * Inbound lines are capped at 1 MiB from the start rather than after the first large frame arrives. An over-long line is discarded and the connection stays up: one malformed frame is not a reason to drop a link live events flow over. * Store-backed reads answer while the game is off, which is what lets a website render a server list during a wipe. /status is the one route that fails when the game is down, and /server answers 204 rather than a null when the game has never connected -- those are different answers and a client that cannot tell them apart renders a server that does not exist. * The two RPC failures get distinct codes. 503 means the game is down; 504 means it is up and did not answer. Different fixes. * rpc::REPLY_TIMEOUT is a ceiling every later command budget sits under: core classifies a budget overrun as retryable unconditionally, so an action whose budgetMs does not exceed it can never report retry:false. One defect found while building, which no unit test would have caught: a four-connection SQLite pool over :memory: hands out four separate empty databases, because an in-memory database is per connection. It presents as 'no such table' from a random subset of queries. The pool is now capped at one connection for an in-memory path, which is the only coherent reading of :memory: and is what makes it usable at all. Exercised end to end against a live Rust server: a server.hello travelled game -> sidecar -> module -> the public website API, and killing this process left the game untouched. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016wDDVXWMDz82WqE1i969r4
93 lines
4.7 KiB
Markdown
93 lines
4.7 KiB
Markdown
# rust-link-sidecar
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Configuration reference and endpoint list. For what this component *is*, see the
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[repo README](../README.md).
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## Configuration
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`sidecar.toml`, resolved in this order: `--config <PATH>`, else `$RUSTLINK_CONFIG`, else
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`./sidecar.toml`. Environment variables override the file; the file overrides the defaults.
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| Key | Env | Default | What it is |
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|---|---|---|---|
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| `[game].bind` | `RUSTLINK_GAME_BIND` | `127.0.0.1:7799` | Where the Oxide plugin dials in |
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| `[game].server_id` | `RUSTLINK_SERVER_ID` | *(empty)* | Optional cross-check against the plugin's own `serverId` |
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| `[web].bind` | `RUSTLINK_WEB_BIND` | `127.0.0.1:8090` | Where the website reaches this sidecar |
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| `[web].auth_token` | `RUSTLINK_WEB_TOKEN` | *(generated)* | The shared secret the website presents |
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| `[store].path` | `RUSTLINK_DB_PATH` | `rust-link.db` | SQLite file |
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Two things about those defaults are load-bearing:
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- **`[game].bind` is loopback, and there is no token on that link.** The plugin and the sidecar
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share a host; `127.0.0.1` *is* the authentication. Binding it to a routable address puts an
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unauthenticated command channel on the network.
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- **A relative `[store].path` resolves against the directory holding `sidecar.toml`**, not the
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working directory. A service manager's working directory must not decide where the database
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lands — on Windows that can be `%SystemRoot%\System32`, or a silently redirected VirtualStore
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copy.
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`[game].server_id` is a **cross-check, not a second source of truth**. The plugin announces its own
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`serverId` and that is the authority; when both are set and they disagree, the sidecar logs the
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disagreement loudly and keeps the plugin's. Two game servers pointed at one sidecar by a copied
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config is the mistake this catches, and it is silent in every other design.
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### Reading the token back
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```bash
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rust-link-sidecar --print-config
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```
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Resolves the configuration exactly as a normal start would — writing the file and generating the
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token if they are missing — and prints it as JSON on stdout, **including the token in clear text**.
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That is the supported way for an installer to obtain it; the alternative is scraping a log.
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## Endpoints
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Everything except `/health` requires the token, as `Authorization: Bearer <t>`, `X-Api-Key: <t>`,
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or `?token=<t>` (the last so browser WebSocket clients, which cannot set handshake headers, can
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still authenticate). Every response carries `X-RustLink-Version`.
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| Route | Backed by | Notes |
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|---|---|---|
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| `GET /health` | — | Unauthenticated, so monitoring can reach it |
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| `GET /server` | store | The last `server.hello`. **`204` when the game has never connected** |
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| `GET /events?kind=&limit=` | store | Newest first; `limit` clamped to 1–1000 |
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| `GET /status` | plugin (RPC) | A live round trip. `503` with no plugin, `504` on no reply |
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| `GET /ws` | broadcast | The live feed. Sends `ws.hello` on connect |
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The split is the point: the store-backed reads answer while the game is off, which is what lets the
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website render a server list during a wipe or a restart. `/status` is the one route that fails when
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the game is down, because "what is it doing right now" has no stale answer worth giving.
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`/server` answers `204`, not `200` with a null, when the game has never connected. "We have never
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heard from this server" and "this server reports nothing" are different answers, and a client that
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cannot tell them apart renders a server that does not exist.
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## Protocol 1
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Newline-delimited JSON over TCP, both directions. Outbound frames (plugin → sidecar) carry `kind`;
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inbound frames (sidecar → plugin) carry `cmd`. Lines are capped at 1 MiB; an over-long line is
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discarded and the connection stays up.
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| Frame | Direction | Purpose |
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|---|---|---|
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| `server.hello` | plugin → sidecar | Sent on **every connect**, not once at server start — this process restarts independently of the game. Carries `serverId` and `bootId` |
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| `ping` / `pong` | sidecar → plugin → sidecar | The heartbeat, every 30s. A `pong` is never persisted; it only moves `last_event` |
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| `server.status` | sidecar → plugin → sidecar | The one request/reply verb, correlated by `reqId` |
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`bootId` is how a game restart is told apart from a sidecar reconnect — the distinction the event
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system's `reconcile` hangs off later.
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**The RPC reply timeout (`rpc::REPLY_TIMEOUT`, 10s) is a ceiling every later command budget sits
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under.** Core classifies a budget overrun as retryable unconditionally, because it cannot ask the
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game while the action is still awaiting a socket. An action whose `budgetMs` exceeds this can never
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report `retry: false`.
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## Checks
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```bash
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cargo fmt --all -- --check
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cargo clippy --all-targets -- -D warnings
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cargo test
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```
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