chore: Merge in work done on old builder (#5)

From https://github.com/zeit/now-builders/pull/863

Author: mike-engel

package.json

@@ -11,8 +11,9 @@
   },
   "scripts": {
     "build": "tsc",
-    "test": "tsc && jest",
+    "now-postinstall": "node dist/install-rust.js",
     "prepublishOnly": "tsc",
+    "test": "tsc && jest",
     "typecheck": "tsc --noEmit"
   },
   "files": [

src/index.ts

@@ -14,7 +14,6 @@ import {
 	DownloadedFiles,
 	Lambda
 } from "@now/build-utils"; // eslint-disable-line import/no-extraneous-dependencies
-import installRust from "./install-rust";
 
 interface PackageManifest {
 	targets: { kind: string; name: string }[];
@@ -275,10 +274,6 @@ export async function build(opts: BuildOptions) {
 	const downloadedFiles = await download(files, workPath, meta);
 	const entryPath = downloadedFiles[entrypoint].fsPath;
 
-	if (!meta.isDev) {
-		await installRust(config.rust);
-	}
-
 	const { PATH, HOME } = process.env;
 	const rustEnv: Record<string, string> = {
 		...process.env,

src/install-rust.ts

@@ -34,7 +34,12 @@ async function installOpenSSL() {
 	}
 }
 
-export default async (version?: string) => {
+export const installRustAndFriends = async (version?: string) => {
 	await downloadRustToolchain(version);
 	await installOpenSSL();
 };
+
+installRustAndFriends().catch(err => {
+	console.error(err);
+	process.exit(1);
+});