fix(spawner): rewrite to use createVat, strip down to bare minimum API

This removes all zoe-like functionality from the spawner, leaving a bare
install() and spawn() API. This is now effectively a wrapper around
createVat(), except that it accepts source code which exports a default
function, rather than an export named `buildRootObject`, and it does not
return the control facet (`adminNode`) to the caller.

Our two cosmic-swingset applications (chain and ag-solo) are updated to
create the spawner correctly. Dapps can continue to use the existing API
without changes.

closes #1343

packages/cosmic-swingset/lib/ag-solo/vats/bootstrap.js

@@ -76,7 +76,7 @@ export function buildRootObject(vatPowers, vatParameters) {
       E(vats.board).getBoard(),
       E(vats.timer).createTimerService(timerDevice),
       /** @type {ERef<ZoeService>} */ (E(vats.zoe).buildZoe(vatAdminSvc)),
-      E(vats.host).makeHost(),
+      E(vats.spawner).buildSpawner(vatAdminSvc),
       E(vats.priceAuthority).makePriceAuthority(),
     ]);
 
@@ -602,10 +602,10 @@ export function buildRootObject(vatPowers, vatParameters) {
   // objects that live in the client's solo vat. Some services should only
   // be in the DApp environment (or only in end-user), but we're not yet
   // making a distinction, so the user also gets them.
-  async function createLocalBundle(vats, devices) {
+  async function createLocalBundle(vats, devices, vatAdminSvc) {
     // This will eventually be a vat spawning service. Only needed by dev
     // environments.
-    const spawner = E(vats.host).makeHost();
+    const spawner = E(vats.spawner).buildSpawner(vatAdminSvc);
 
     // Needed for DApps, maybe for user clients.
     const uploads = E(vats.uploads).getUploads();
@@ -725,7 +725,11 @@ export function buildRootObject(vatPowers, vatParameters) {
             GCI,
             PROVISIONER_INDEX,
           );
-          const localBundle = await createLocalBundle(vats, devices);
+          const localBundle = await createLocalBundle(
+            vats,
+            devices,
+            vatAdminSvc,
+          );
           await E(vats.http).setPresences(localBundle);
           const bundle = await E(demoProvider).getDemoBundle();
           await E(vats.http).setPresences(localBundle, bundle, {

packages/cosmic-swingset/lib/ag-solo/vats/chain-config.json

@@ -9,8 +9,8 @@
     "board": {
       "sourceSpec": "vat-board.js"
     },
-    "host": {
-      "sourceSpec": "vat-host.js"
+    "spawner": {
+      "sourceSpec": "vat-spawner.js"
     },
     "ibc": {
       "sourceSpec": "vat-ibc.js"

packages/cosmic-swingset/lib/ag-solo/vats/solo-config.json

@@ -1,8 +1,8 @@
 {
   "bootstrap": "bootstrap",
   "vats": {
-    "host": {
-      "sourceSpec": "vat-host.js"
+    "spawner": {
+      "sourceSpec": "vat-spawner.js"
     },
     "http": {
       "sourceSpec": "vat-http.js"

packages/cosmic-swingset/lib/ag-solo/vats/vat-spawner.js

@@ -0,0 +1,13 @@
+// Copyright (C) 2018 Agoric, under Apache License 2.0
+import { Far } from '@agoric/marshal';
+import { makeSpawner } from '@agoric/spawner';
+
+function buildRootObject() {
+  return Far('root', {
+    buildSpawner(vatAdminSvc) {
+      return makeSpawner(vatAdminSvc);
+    },
+  });
+}
+harden(buildRootObject);
+export { buildRootObject };

packages/spawner/README.md

@@ -1,4 +1,56 @@
 # Spawner
 
-The original contractHost, which will be turned into a general purpose
-vat spawner now that we have Zoe for most smart contracts.
+The "spawner" was the original method for instantiating contract code within
+the chain's swingset. This on-chain usage has been entirely superceded by
+Zoe, and the chain swingset no longer includes a spawner.
+
+However, it was also pressed into service in the ag-solo swingset for
+executing deploy scripts that need to leave code running after the script
+finishes, such as an HTTP API handler. This use case is still active, but
+none of the callers need the zoe-like features (comparable contract identity,
+source retrieval, issuers, invitations, or seats). These callers now do
+something like:
+
+```js
+  const bundle = await bundleSource(pathResolve(__dirname, './src/wallet.js'));
+  const walletInstall = E(spawner).install(bundle);
+  const walletVat = await E(walletInstall).spawn(args);
+```
+
+So the spawner is now a stripped-down dynamic-vat creation frontend with the
+minimal code necessary to satisfy those callers.
+
+The spawner expects to be running in a vat. It used to evaluate the submitted
+code in its own vat, under "within-vat" metering to protect itself from
+runaway guest code. It has been rewritten to evaluate the guest in a new
+dynamic vat instead.
+
+To support a spawner, your swingset must provide it with the `vatAdmin` facet
+(to create new vats), and a copy of the `vat-spawned.js` bundle (to install
+in the new vat). Your `vat-spawner.js` should look like:
+
+```js
+import { Far } from '@agoric/marshal';
+import { makeSpawner } from '@agoric/spawner';
+function buildRootObject() {
+  return Far('root', {
+    buildSpawner(vatAdminSvc) {
+      return makeSpawner(vatAdminSvc);
+    }
+  });
+}
+harden(buildRootObject);
+export { buildRootObject };
+```
+
+And your bootstrap function needs something like this:
+
+```js
+return Far('root', {
+  async bootstrap(vats, devices) {
+    const vatAdminSvc = await E(vats.vatAdmin).createVatAdminService(
+      devices.vatAdmin,
+    );
+    const spawner = await E(vats.spawner).buildSpawner(vatAdminSvc);
+    // ...
+```

packages/spawner/package.json

@@ -10,7 +10,8 @@
     "node": ">=11.0"
   },
   "scripts": {
-    "build": "exit 0",
+    "build": "yarn build-bundle-spawn",
+    "build-bundle-spawn": "node -r esm scripts/build-bundle-spawn.js",
     "test": "ava",
     "test:nyc": "nyc ava",
     "test:xs": "exit 0",
@@ -32,17 +33,12 @@
   "homepage": "https://github.com/Agoric/agoric-sdk#readme",
   "dependencies": {
     "@agoric/assert": "^0.2.8",
-    "@agoric/ertp": "^0.10.7",
     "@agoric/eventual-send": "^0.13.10",
     "@agoric/import-bundle": "^0.2.10",
-    "@agoric/marshal": "^0.4.7",
-    "@agoric/nat": "^4.0.0",
-    "@agoric/promise-kit": "^0.2.9",
-    "@agoric/same-structure": "^0.1.9",
-    "@agoric/store": "^0.4.10",
-    "@agoric/transform-metering": "^1.4.8"
+    "@agoric/marshal": "^0.4.7"
   },
   "devDependencies": {
+    "@agoric/bundle-source": "^1.3.3",
     "@agoric/install-metering-and-ses": "^0.2.9",
     "@agoric/install-ses": "^0.5.9",
     "@agoric/swingset-vat": "^0.16.3",

packages/spawner/scripts/build-bundle-spawn.js

@@ -0,0 +1,33 @@
+/* global __dirname */
+
+// eslint-disable-next-line import/no-extraneous-dependencies
+import 'ses';
+import fs from 'fs';
+import process from 'process';
+import bundleSource from '@agoric/bundle-source';
+
+async function writeSourceBundle(contractFilename, outputPath) {
+  await bundleSource(contractFilename).then(bundle => {
+    // TODO: fix
+    // @ts-ignore mkdirSync believes it only accepts 2 arguments.
+    fs.mkdirSync(`${__dirname}/../bundles`, { recursive: true }, err => {
+      if (err) throw err;
+    });
+    fs.writeFileSync(outputPath, `export default ${JSON.stringify(bundle)};`);
+  });
+}
+
+async function main() {
+  const contractFilename = `${__dirname}/../src/vat-spawned.js`;
+  const outputPath = `${__dirname}/../bundles/bundle-spawn.js`;
+  await writeSourceBundle(contractFilename, outputPath);
+}
+
+main().then(
+  _ => process.exit(0),
+  err => {
+    console.log('error creating spawn bundle:');
+    console.log(err);
+    process.exit(1);
+  },
+);