# toybox

Vats whose code is installed at runtime: each vat is a Durable Object whose app runs as a [facet](https://developers.cloudflare.com/dynamic-workers/usage/durable-object-facets/) on code loaded through workerd's Worker Loader. Think `vatAdmin.createVat(bundle)`, with a supervisor per vat.

- [supervisor.js](supervisor.js): `Vat` stores code by SHA-256 and runs the app on it; `Public` and `Admin` are the two entrypoints.
- [config.capnp](config.capnp): the sockets have no addresses; whoever starts workerd hands them in, so holding a socket is the authority it grants.

| socket | reaches | what its holder can do |
|---|---|---|
| `http` | `Public` | `GET /<vat>/…`: talk to a vat's app |
| `admin` | `Admin` | `PUT /<vat>` with an ES module body: install it and (re)start the app; its storage carries over |

An app must export `class App extends DurableObject` (see [apps/](apps/)). It gets an empty `env` and no `fetch`.

## Run it

```sh
pnpm install
pnpm test     # a real workerd: install, upgrade, isolation, no fetch, crash and restart
pnpm start    # systemd-socket-activate on 127.0.0.1:8787 and ./admin.sock; state in ./state
```

Then, in another terminal:

```sh
curl -X PUT --unix-socket admin.sock --data-binary @apps/counter-v1.js http://toybox/alice
curl localhost:8787/alice                # v1 count 1
curl -X PUT --unix-socket admin.sock --data-binary @apps/counter-v2.js http://toybox/alice
curl localhost:8787/alice                # v2 count 2
```

## Under systemd

[systemd/](systemd/) has a socket and service pair, assuming this directory is installed at `/opt/toybox`. The service gets no network of its own (`PrivateNetwork=yes`): only the two sockets it is handed.

`PrivateNetwork=` needs the system manager; as a `systemd-run --user` unit, systemd logs "lack privileges for network namespace, proceeding without".