> ## Documentation Index > Fetch the complete documentation index at: https://docs.eucaengine.com/llms.txt > Use this file to discover all available pages before exploring further. # Hosting & deployment > Stand up a server an agent or model can drive: pick the hosting class (headless / needs-GPU / needs-device), set the port, and understand the unauthenticated-local auth posture. Euca is **self-hosted and developer-facing**: you run one server, and a client — your code, the [CLI](/concepts/the-cli), or a model under [evaluation](/evaluation/overview) — drives it over a single HTTP API. To stand up a server an agent can drive, you pick a **hosting class** for what it needs (a bare headless host, a GPU host, or a host with an OS device), boot it on a known port bound to localhost, and point your client at it. This page is the operational picture; every port and boot fact below is captured from a running server. ## Stand up a server an agent can drive Run the headless host (`euca-studio` with no window): ```bash theme={null} cargo run -p euca-studio -- --headless ``` It serves the agent HTTP API on `3917` and runs the project's full game logic, with no window or GPU. Pass a project id (`-- --headless `) to pick which project to serve; with none, the first discovered project is used. It boots immediately and logs its address; the root endpoint is your health check and reports the engine version and tick: ```bash theme={null} curl -s http://localhost:3917/ # {"engine":"Euca Engine","version":"1.1.0","entity_count":107,"archetype_count":18,"tick":100} ``` The `entity_count` and `tick` reflect the **loaded project** (the headless host boots a full world), so your numbers will differ; the engine version and liveness are what this check confirms. The server binds **`127.0.0.1`** (localhost only) on port **3917** — the CLI and the OpenAPI reference default to it too. POST requests must send `Content-Type: application/json`. `POST /step` is **capped at 10,000 ticks per call**, silently — asking for more advances only 10,000: ```bash theme={null} curl -s -X POST http://localhost:3917/step -H 'Content-Type: application/json' -d '{"ticks":100000}' # {"ticks_advanced":10000,"new_tick":10001,"entity_count":...} ``` ## Pick a hosting class The headless host runs the project's **full game logic** each tick — its rules, combat, and any systems the game schedules, plus stepping and forks. Other subsystems need more from the host than a window-less process can provide: | Class | What it needs | Subsystems | | ------------------------- | ------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------- | | **Headless (default)** | Nothing — runs anywhere the engine builds | The project's gameplay, rules, stepping, forks | | **Needs a host resource** | Register the resource in your game or host build | [Lua scripting](/systems/scripting-lua) (`ScriptEngine`), [templates/prefabs](/systems/templates-and-prefabs), [input bindings](/systems/input) | | **Needs an OS device** | A machine with audio hardware | [Audio](/systems/audio) (`AudioEngine`) | | **Needs a GPU** | A GPU host | [Camera & rendering](/systems/camera-and-rendering) | On a bare headless host those host-dependent features return an honest error rather than failing silently — e.g. `/script/load` → `No ScriptEngine resource in world`, `/audio/play` → `AudioEngine not initialized`. Wire the resource (or run on the right hardware) and the same call works. ## Point clients at a host There is **no `EUCA_URL` environment variable** in the engine — clients take a base URL directly: * **CLI** — `euca --server http://localhost:3917 ` (default is `http://localhost:3917`). * **HTTP** — your client sets the base URL itself; for a hosted deployment, point it at the host's URL. ## Auth posture * **Local / self-hosted: unauthenticated by default.** A localhost server has no global auth gate — token-less calls succeed, so `/step`, `/observe`, and `/fork` just work. This is the intended posture for a trusted dev environment. * **Opt-in Ed25519 auth is shipped, not scaffolding.** Install an `AuthStore` and `POST /auth/login` verifies an Ed25519 signature (nit-compatible) and issues a session token; `GET /auth/status` validates the bearer token; and a per-agent ownership layer (`Owner` component) gates scoped scene routes (401 on an id mismatch). Without an `AuthStore` installed it stays off and calls run unauthenticated — auth here is **opt-in ownership, not a global gate you must pass**. * **Hosted / benchmark access** can additionally layer an API key **at the hosting tier** (e.g. a reverse proxy) — the truth-hiding [evaluation](/evaluation/overview) boundary is the relevant access control for graded runs. ## Platforms & what's not here * **Platforms** — macOS and Linux. The headless host has no GPU dependency and runs anywhere the engine builds. * **No managed/cloud offering yet.** No Docker image, Kubernetes manifest, CI/CD deploy pipeline, multi-tenancy, rate limiting, or built-in monitoring ships in the repo. Containerizing the single binary is straightforward, but no reference deployment ships today — treat hosting as "run the binary behind your own infrastructure." ## Status * **Shipped** — the headless host (`euca-studio --headless`), localhost bind on 3917, the 10,000-tick step cap, and opt-in Ed25519 auth (`/auth/*` login + per-agent ownership), off by default. All headless. * **Not here** — a managed/cloud offering, container/orchestration manifests, and a *required* global authentication gate on the local server (auth is opt-in ownership, not a middleware every call must pass). Every endpoint an agent or model can drive a hosted server with, with request and response schemas.