Adapters v0 (#2855)

* Adapter v0

* Finalizing adapters

* Update the lockfile

* Add the default adapter after config setup is called

* Create the default adapter in config:done

* Fix lint error

* Remove unused callConfigSetup

* remove unused export

* Use a test adapter to test SSR

* Adds a changeset

* Updated based on feedback

* Updated the lockfile

* Only throw if set to a different adapter

* Clean up outdated comments

* Move the adapter to an  config option

* Make adapter optional

* Update the docs/changeset to reflect config API change

* Clarify regular Node usage

5 files changed, 163 insertions, 0 deletions

diff --git a/packages/integrations/node/package.json b/packages/integrations/node/package.json
new file mode 100644
index 000000000..1208dbd4a
--- /dev/null
+++ b/packages/integrations/node/package.json
@@ -0,0 +1,32 @@
+{
+  "name": "@astrojs/node",
+  "description": "Deploy your site to a Node.js server",
+  "version": "0.0.1",
+  "type": "module",
+  "types": "./dist/index.d.ts",
+  "author": "withastro",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/withastro/astro.git",
+    "directory": "packages/integrations/node"
+  },
+  "bugs": "https://github.com/withastro/astro/issues",
+  "homepage": "https://astro.build",
+  "exports": {
+    ".": "./dist/index.js",
+    "./server.js": "./dist/server.js",
+    "./package.json": "./package.json"
+  },
+  "scripts": {
+    "build": "astro-scripts build \"src/**/*.ts\" && tsc",
+    "dev": "astro-scripts dev \"src/**/*.ts\""
+  },
+  "dependencies": {
+    "@astrojs/webapi": "^0.11.0"
+  },
+  "devDependencies": {
+    "astro": "workspace:*",
+    "astro-scripts": "workspace:*"
+  }
+}
diff --git a/packages/integrations/node/readme.md b/packages/integrations/node/readme.md
new file mode 100644
index 000000000..011485278
--- /dev/null
+++ b/packages/integrations/node/readme.md
@@ -0,0 +1,53 @@
+# @astrojs/node
+
+An experimental static-side rendering adapter for use with Node.js servers.
+
+In your astro.config.mjs use:
+
+```js
+import nodejs from '@astrojs/node';
+
+export default {
+  adapter: nodejs()
+}
+```
+
+After performing a build there will be a `dist/server/entry.mjs` module that works like a middleware function. You can use with any framework that supports the Node `request` and `response` objects. For example, with Express you can do:
+
+```js
+import express from 'express';
+import { handler as ssrHandler } from './dist/server/entry.mjs';
+
+const app = express();
+app.use(ssrHandler);
+
+app.listen(8080);
+```
+
+# Using `http`
+
+This adapter does not require you use Express and can work with even the `http` and `https` modules. The adapter does following the Expression convention of calling a function when either
+
+- A route is not found for the request.
+- There was an error rendering.
+
+You can use these to implement your own 404 behavior like so:
+
+```js
+import http from 'http';
+import { handler as ssrHandler } from './dist/server/entry.mjs';
+
+http.createServer(function(req, res) {
+  ssrHandler(req, res, err => {
+    if(err) {
+      res.writeHead(500);
+      res.end(err.toString());
+    } else {
+      // Serve your static assets here maybe?
+      // 404?
+      res.writeHead(404);
+      res.end();
+    }
+  });
+}).listen(8080);
+```
diff --git a/packages/integrations/node/src/index.ts b/packages/integrations/node/src/index.ts
new file mode 100644
index 000000000..903d5b1cc
--- /dev/null
+++ b/packages/integrations/node/src/index.ts
@@ -0,0 +1,20 @@
+import type { AstroAdapter, AstroIntegration } from 'astro';
+
+export function getAdapter(): AstroAdapter {
+	return {
+		name: '@astrojs/node',
+		serverEntrypoint: '@astrojs/node/server.js',
+		exports: ['handler'],
+	};
+}
+
+export default function createIntegration(): AstroIntegration {
+	return {
+		name: '@astrojs/node',
+		hooks: {
+			'astro:config:done': ({ setAdapter }) => {
+				setAdapter(getAdapter());
+			}
+		}
+	};
+}
diff --git a/packages/integrations/node/src/server.ts b/packages/integrations/node/src/server.ts
new file mode 100644
index 000000000..791dc58b2
--- /dev/null
+++ b/packages/integrations/node/src/server.ts
@@ -0,0 +1,48 @@
+import type { SSRManifest } from 'astro';
+import type { IncomingMessage, ServerResponse } from 'http';
+import { NodeApp } from 'astro/app/node';
+import { polyfill } from '@astrojs/webapi';
+
+polyfill(globalThis, {
+	exclude: 'window document'
+});
+
+export function createExports(manifest: SSRManifest) {
+	const app = new NodeApp(manifest, new URL(import.meta.url));
+	return {
+		async handler(req: IncomingMessage, res: ServerResponse, next?: (err?: unknown) => void) {
+			const route = app.match(req);
+
+			if(route) {
+				try {
+					const response = await app.render(req);
+					await writeWebResponse(res, response);
+				} catch(err: unknown) {
+					if(next) {
+						next(err);
+					} else {
+						throw err;
+					}
+				}
+			} else if(next) {
+				return next();
+			}
+		}
+	}
+}
+
+async function writeWebResponse(res: ServerResponse, webResponse: Response) {
+	const { status, headers, body } = webResponse;
+	res.writeHead(status, Object.fromEntries(headers.entries()));
+	if (body) {
+		const reader = body.getReader();
+		while (true) {
+			const { done, value } = await reader.read();
+			if (done) break;
+			if (value) {
+				res.write(value);
+			}
+		}
+	}
+	res.end();
+}
diff --git a/packages/integrations/node/tsconfig.json b/packages/integrations/node/tsconfig.json
new file mode 100644
index 000000000..44baf375c
--- /dev/null
+++ b/packages/integrations/node/tsconfig.json
@@ -0,0 +1,10 @@
+{
+  "extends": "../../../tsconfig.base.json",
+  "include": ["src"],
+  "compilerOptions": {
+    "allowJs": true,
+    "module": "ES2020",
+    "outDir": "./dist",
+    "target": "ES2020"
+  }
+}