Fixes API route compat with Node 14 (#2936)

* Fixes API route compat with Node 14

* Changeset

4 files changed, 49 insertions, 7 deletions

diff --git a/.changeset/odd-swans-walk.md b/.changeset/odd-swans-walk.md
new file mode 100644
index 000000000..0c406d7e0
--- /dev/null
+++ b/.changeset/odd-swans-walk.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes non-GET API routes in dev with Node 14
diff --git a/packages/astro/src/vite-plugin-astro-server/index.ts b/packages/astro/src/vite-plugin-astro-server/index.ts
index 4a5b1a5fc..3294b4948 100644
--- a/packages/astro/src/vite-plugin-astro-server/index.ts
+++ b/packages/astro/src/vite-plugin-astro-server/index.ts
@@ -15,6 +15,7 @@ import serverErrorTemplate from '../template/5xx.js';
 import { RouteCache } from '../core/render/route-cache.js';
 import { fixViteErrorMessage } from '../core/errors.js';
 import { createRequest } from '../core/request.js';
+import { Readable } from 'stream';
 
 interface AstroPluginOptions {
 	config: AstroConfig;
@@ -44,12 +45,17 @@ async function writeWebResponse(res: http.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);
+		if(body instanceof Readable) {
+			body.pipe(res);
+			return;
+		} else {
+			const reader = body.getReader();
+			while (true) {
+				const { done, value } = await reader.read();
+				if (done) break;
+				if (value) {
+					res.write(value);
+				}
 			}
 		}
 	}
@@ -134,7 +140,7 @@ async function handleRequest(
 		await new Promise((resolve) => {
 			req.setEncoding('utf-8');
 			req.on('data', (bts) => bytes.push(bts));
-			req.on('close', resolve);
+			req.on('end', resolve);
 		});
 		body = new TextEncoder().encode(bytes.join('')).buffer;
 	}
diff --git a/packages/astro/test/fixtures/ssr-api-route/src/pages/food.json.js b/packages/astro/test/fixtures/ssr-api-route/src/pages/food.json.js
index 0003f2ad4..fecf83051 100644
--- a/packages/astro/test/fixtures/ssr-api-route/src/pages/food.json.js
+++ b/packages/astro/test/fixtures/ssr-api-route/src/pages/food.json.js
@@ -8,3 +8,13 @@ export function get() {
 		])
 	};
 }
+
+export async function post(params, request) {
+	const body = await request.text();
+	return new Response(body === `some data` ? `ok` : `not ok`, {
+		status: 200,
+		headers: {
+			'Content-Type': 'application/x-www-form-urlencoded'
+		}
+	});
+}
diff --git a/packages/astro/test/ssr-api-route.test.js b/packages/astro/test/ssr-api-route.test.js
index 2131c2b6f..cf053a8db 100644
--- a/packages/astro/test/ssr-api-route.test.js
+++ b/packages/astro/test/ssr-api-route.test.js
@@ -36,4 +36,25 @@ describe('API routes in SSR', () => {
 		const body = await response.json();
 		expect(body.length).to.equal(3);
 	});
+
+	describe('Dev', () => {
+		let devServer;
+		before(async () => {
+			devServer = await fixture.startDevServer();
+		});
+
+		after(async () => {
+			await devServer.stop();
+		});
+
+		it('Can POST to API routes', async () => {
+			const response = await fixture.fetch('/food.json', {
+				method: 'POST',
+				body: `some data`
+			})
+			expect(response.status).to.equal(200);
+			const text = await response.text();
+			expect(text).to.equal(`ok`);
+		});
+	});
 });