feat(aws-serverless): Add lambda extension to npm package

This PR adds the Lambda Extension as a build output to the npm package. It was
previously only available through our Lambda layer but is useful for users that
do not use the layer but would still like to use our extension.

To use the extension with container image lambdas, copy the extension files to
your Docker image and set the `tunnel` option in your application. This requires
the installation of `@sentry/aws-serverless`, regardless of which other Sentry
SDK is used in your application.

```dockerfile
    RUN mkdir -p /opt/sentry-extension
    COPY node_modules/@sentry/aws-serverless/build/lambda-extension/sentry-extension
  /opt/extensions/sentry-extension
    COPY node_modules/@sentry/aws-serverless/build/lambda-extension/index.mjs
  /opt/sentry-extension/index.mjs
    RUN chmod +x /opt/extensions/sentry-extension /opt/sentry-extension/index.mjs
```

```js
  Sentry.init({
    dsn: '__DSN__',
    tunnel: 'http://localhost:9000/envelope',
  });
```

Closes: #20114

Author: andreiborza

packages/aws-serverless/README.md

@@ -73,6 +73,50 @@ export const handler = (event, context, callback) => {
 };
 ```
 
+## Container Image-based Lambda Functions
+
+When using container image-based Lambda functions (e.g., with [Lambda Web Adapter](https://github.com/awslabs/aws-lambda-web-adapter) for frameworks like SvelteKit, Next.js, or Remix), Lambda layers cannot be attached. Instead, you can install the Sentry Lambda extension directly into your Docker image. The extension tunnels Sentry events through a local proxy, improving event delivery reliability during Lambda freezes.
+
+### Setup
+
+1. Install `@sentry/aws-serverless` as a dependency — even if you use a different Sentry SDK in your application (e.g., `@sentry/sveltekit`), this package contains the extension files needed for the Docker image.
+
+2. Copy the extension files from the npm package into your Docker image:
+
+```dockerfile
+FROM public.ecr.aws/lambda/nodejs:22
+
+# Copy the Sentry Lambda extension
+RUN mkdir -p /opt/sentry-extension
+COPY node_modules/@sentry/aws-serverless/build/lambda-extension/sentry-extension /opt/extensions/sentry-extension
+COPY node_modules/@sentry/aws-serverless/build/lambda-extension/index.mjs /opt/sentry-extension/index.mjs
+RUN chmod +x /opt/extensions/sentry-extension /opt/sentry-extension/index.mjs
+
+# ... rest of your Dockerfile
+```
+
+3. Point your Sentry SDK at the extension using the `tunnel` option. The extension always listens on `http://localhost:9000/envelope` — this URL is fixed and must be used exactly as shown:
+
+```js
+import * as Sentry from '@sentry/aws-serverless';
+
+Sentry.init({
+  dsn: '__DSN__',
+  tunnel: 'http://localhost:9000/envelope',
+});
+```
+
+This works with any Sentry SDK:
+
+```js
+import * as Sentry from '@sentry/sveltekit';
+
+Sentry.init({
+  dsn: '__DSN__',
+  tunnel: 'http://localhost:9000/envelope',
+});
+```
+
 ## Integrate Sentry using the Sentry Lambda layer
 
 Another much simpler way to integrate Sentry to your AWS Lambda function is to add the official layer.

packages/aws-serverless/package.json

@@ -12,7 +12,8 @@
   "files": [
     "/build/npm",
     "/build/import-hook.mjs",
-    "/build/loader-hook.mjs"
+    "/build/loader-hook.mjs",
+    "/build/lambda-extension"
   ],
   "main": "build/npm/cjs/index.js",
   "module": "build/npm/esm/index.js",
@@ -79,8 +80,9 @@
     "@vercel/nft": "^1.3.0"
   },
   "scripts": {
-    "build": "run-p build:transpile build:types && run-s build:layer",
-    "build:layer": "rimraf build/aws && rollup -c rollup.lambda-extension.config.mjs && yarn ts-node scripts/buildLambdaLayer.ts",
+    "build": "run-p build:transpile build:types build:extension && run-s build:layer",
+    "build:extension": "rollup -c rollup.lambda-extension.config.mjs && yarn ts-node scripts/buildLambdaExtension.ts",
+    "build:layer": "rimraf build/aws && yarn ts-node scripts/buildLambdaLayer.ts",
     "build:dev": "run-p build:transpile build:types",
     "build:transpile": "rollup -c rollup.npm.config.mjs",
     "build:types": "run-s build:types:core build:types:downlevel",
@@ -118,13 +120,26 @@
           "{projectRoot}/build/npm/cjs"
         ]
       },
+      "build:extension": {
+        "inputs": [
+          "production",
+          "^production"
+        ],
+        "dependsOn": [
+          "^build:transpile"
+        ],
+        "outputs": [
+          "{projectRoot}/build/lambda-extension"
+        ]
+      },
       "build:layer": {
         "inputs": [
           "production",
           "^production"
         ],
         "dependsOn": [
-          "build:transpile"
+          "build:transpile",
+          "build:extension"
         ],
         "outputs": [
           "{projectRoot}/build/aws"

packages/aws-serverless/rollup.lambda-extension.config.mjs

@@ -7,7 +7,7 @@ export default [
     outputFileBase: 'index.mjs',
     packageSpecificConfig: {
       output: {
-        dir: 'build/aws/dist-serverless/sentry-extension',
+        dir: 'build/lambda-extension',
         sourcemap: false,
       },
     },

packages/aws-serverless/scripts/buildLambdaExtension.ts

@@ -0,0 +1,18 @@
+import * as fs from 'fs';
+
+// Copy the bash wrapper script into the rollup output directory
+// so the npm package ships both the compiled extension and the wrapper.
+const targetDir = './build/lambda-extension';
+const source = './src/lambda-extension/sentry-extension';
+const target = `${targetDir}/sentry-extension`;
+
+if (!fs.existsSync(targetDir)) {
+  fs.mkdirSync(targetDir, { recursive: true });
+}
+
+fs.copyFileSync(source, target);
+
+// The wrapper must be executable because AWS Lambda discovers extensions by
+// scanning /opt/extensions/ for executable files. If the file isn't executable,
+// Lambda won't register it as an extension.
+fs.chmodSync(target, 0o755);

packages/aws-serverless/scripts/buildLambdaLayer.ts

@@ -54,10 +54,17 @@ async function buildLambdaLayer(): Promise<void> {
 
   replaceSDKSource();
 
+  // Copy the Lambda extension from the shared build output into the layer structure.
+  // build/lambda-extension/ contains both index.mjs and the sentry-extension wrapper.
+  // Lambda requires the wrapper to be in /opt/extensions/ for auto-discovery,
+  // so it gets copied there separately.
+  fs.cpSync('./build/lambda-extension', './build/aws/dist-serverless/sentry-extension', { recursive: true });
   fsForceMkdirSync('./build/aws/dist-serverless/extensions');
-  fs.copyFileSync('./src/lambda-extension/sentry-extension', './build/aws/dist-serverless/extensions/sentry-extension');
+  fs.copyFileSync(
+    './build/aws/dist-serverless/sentry-extension/sentry-extension',
+    './build/aws/dist-serverless/extensions/sentry-extension',
+  );
   fs.chmodSync('./build/aws/dist-serverless/extensions/sentry-extension', 0o755);
-  fs.chmodSync('./build/aws/dist-serverless/sentry-extension/index.mjs', 0o755);
 
   const zipFilename = `sentry-node-serverless-${version}.zip`;
   // Only include these directories in the zip file