fix(dev): drain connections before force-closing the dev server

Author: danielroe

packages/nuxt-cli/src/dev/listen.ts

@@ -69,6 +69,9 @@ const ANY_HOSTS = new Set(['', '0.0.0.0', '::'])
 const LOOPBACK_HOSTS = new Set(['localhost', '127.0.0.1', '::1'])
 const DEFAULT_PORTS = { http: 80, https: 443 } as const
 
+/** How long in-flight requests have to finish before their sockets are killed. */
+const CONNECTION_DRAIN_TIMEOUT_MS = 1000
+
 /**
  * Render a URL for display: the port is omitted when it is the protocol
  * default, and percent-encoding is decoded so a non-ASCII `baseURL` is
@@ -270,8 +273,23 @@ export async function listen(handler: RequestListener, options: ListenOptions =
     close: async () => {
       await tunnel?.close()
       return new Promise<void>((resolve, reject) => {
-        server.close(error => (error ? reject(error) : resolve()))
-        server.closeAllConnections?.()
+        let forceClose: NodeJS.Timeout | undefined
+        server.close((error) => {
+          if (forceClose) {
+            clearTimeout(forceClose)
+          }
+          if (error) {
+            reject(error)
+          }
+          else {
+            resolve()
+          }
+        })
+        // Sockets waiting on keep-alive are closed at once, so shutdown is only
+        // delayed while a request is actually being served.
+        server.closeIdleConnections?.()
+        forceClose = setTimeout(() => server.closeAllConnections?.(), CONNECTION_DRAIN_TIMEOUT_MS)
+        forceClose.unref()
       })
     },
   }

packages/nuxt-cli/test/unit/listen.spec.ts

@@ -202,6 +202,35 @@ describe('listen', () => {
   })
 })
 
+describe('listener.close', () => {
+  it('should let an in-flight request finish', async () => {
+    let respond: (() => void) | undefined
+    const listener = await listen((_req, res) => {
+      respond = () => res.end('done')
+    }, { port: 0, hostname: '127.0.0.1', showURL: false })
+
+    const response = fetch(listener.url)
+    await vi.waitFor(() => expect(respond).toBeDefined())
+
+    const closed = listener.close()
+    respond!()
+
+    await expect((await response).text()).resolves.toBe('done')
+    await closed
+  })
+
+  it('should not wait for idle keep-alive connections', async () => {
+    const listener = await listen((_req, res) => res.end('ok'), { port: 0, hostname: '127.0.0.1', showURL: false })
+
+    await fetch(listener.url).then(response => response.text())
+
+    const start = Date.now()
+    await listener.close()
+
+    expect(Date.now() - start).toBeLessThan(500)
+  })
+})
+
 describe('copyURL', () => {
   afterEach(() => {
     restoreEnvironment()