Enable manual graceful shutdown

docs/01-app/02-guides/self-hosting.mdx

@@ -253,16 +253,23 @@ You can set the env variable `NEXT_MANUAL_SIG_HANDLE` to `true` and then registe
 }
 ```
 
-```js filename="pages/_document.js"
+```js filename="app/layout.tsx"
 if (process.env.NEXT_MANUAL_SIG_HANDLE) {
-  process.on('SIGTERM', () => {
-    console.log('Received SIGTERM: cleaning up')
-    process.exit(0)
-  })
-  process.on('SIGINT', () => {
-    console.log('Received SIGINT: cleaning up')
-    process.exit(0)
-  })
+  let sigHandled = false
+  const handleSig = () => {
+    if (sigHandled) return
+    sigHandled = true
+
+    console.log('Received SIGINT/SIGTERM: cleaning up')
+
+    // Run clean up
+
+    // Trigger Next.js graceful shutdown
+    process.env.NEXT_MANUAL_SIG_HANDLE = false
+    process.emit('SIGTERM')
+  }
+  process.on('SIGTERM', handleSig)
+  process.on('SIGINT', handleSig)
 }
 ```
 

packages/next/src/server/lib/start-server.ts

@@ -386,6 +386,9 @@ export async function startServer(
         let cleanupStarted = false
         let closeUpgraded: (() => void) | null = null
         const cleanup = () => {
+          // Allow the graceful termination to be manually configurable
+          if (process.env.NEXT_MANUAL_SIG_HANDLE) return
+
           if (cleanupStarted) {
             // We can get duplicate signals, e.g. when `ctrl+c` is used in an
             // interactive shell (i.e. bash, zsh), the shell will recursively
@@ -422,11 +425,8 @@ export async function startServer(
         }
 
         // Make sure commands gracefully respect termination signals (e.g. from Docker)
-        // Allow the graceful termination to be manually configurable
-        if (!process.env.NEXT_MANUAL_SIG_HANDLE) {
-          process.on('SIGINT', cleanup)
-          process.on('SIGTERM', cleanup)
-        }
+        process.on('SIGINT', cleanup)
+        process.on('SIGTERM', cleanup)
 
         const initResult = await getRequestHandlers({
           dir,