Refactor Lambda Layer bundling (#173)

*Issue #, if available:*

*Description of changes:*
#171 introduced a bug where the Lambda server span was no longer
produced in trace map for ESM-based handlers. This PR fixes the bug and
now bundles the lambda layer directly instead of the autoinstrumentation
package. The size of the bundled layer is now ~920KB, a nearly 94%
reduction in size from the original 14.5MB.

The following files were copied from upstream to support Lambda layer
bundling with minor changes: `webpack.config.js`,
`tsconfig.webpack.json`, `tsconfig.esm.json`, and`install-externals.sh`.

Trace Map for CJS handler:

![image](https://github.com/user-attachments/assets/fe319402-db2b-41c9-b28d-14c6953ac2ba)

Trace Map for ESM handler:

![image](https://github.com/user-attachments/assets/d70f91f0-2c49-40b0-b3e4-4270ba39648f)

Trace Map for ESM handler prior to fix (with bug):

![image](https://github.com/user-attachments/assets/fa0e5726-e485-4029-9b01-9e68cf6d7a5e)


By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Author: ezhang6811

aws-distro-opentelemetry-node-autoinstrumentation/package.json

@@ -22,9 +22,7 @@
   "repository": "aws-observability/aws-otel-js-instrumentation",
   "scripts": {
     "clean": "rimraf build/*",
-    "compile:tsc": "tsc -p .",
-    "compile:webpack": "webpack",
-    "compile": "npm run compile:webpack",
+    "compile": "tsc -p .",
     "lint": "eslint . --ext .ts",
     "lint:fix": "eslint . --ext .ts --fix",
     "create-version": "node -p \"'export const LIB_VERSION = ' + JSON.stringify(require('./package.json').version) + ';'\" > src/version.ts",
@@ -95,11 +93,8 @@
     "proxyquire": "^2.1.3",
     "rimraf": "5.0.5",
     "sinon": "15.2.0",
-    "ts-loader": "^9.5.2",
     "ts-mocha": "10.0.0",
-    "typescript": "4.4.4",
-    "webpack": "^5.98.0",
-    "webpack-cli": "^6.0.1"
+    "typescript": "4.4.4"
   },
   "dependencies": {
     "@opentelemetry/api": "1.9.0",
@@ -115,7 +110,6 @@
     "@opentelemetry/instrumentation-aws-sdk": "0.49.0",
     "@opentelemetry/otlp-transformer": "0.57.1",
     "@opentelemetry/propagator-aws-xray": "1.26.2",
-    "@opentelemetry/propagator-aws-xray-lambda": "^0.54.0",
     "@opentelemetry/resource-detector-aws": "1.12.0",
     "@opentelemetry/resources": "1.30.1",
     "@opentelemetry/sdk-metrics": "1.30.1",
@@ -127,7 +121,6 @@
     "build/src/**/*.js",
     "build/src/**/*.js.map",
     "build/src/**/*.d.ts",
-    "build/src/**/*.d.ts.map",
     "build/src/**/*.json"
   ]
 }

aws-distro-opentelemetry-node-autoinstrumentation/tsconfig.webpack.json

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+set -euf -o pipefail
+
+# Space separated list of external NPM packages
+
+# import-in-the-middle's hook.mjs is used as a module loader for ESM-based handlers and must be available at runtime,
+# so we have to install it a standalone package separate from the bundled layer.
+EXTERNAL_PACKAGES=( "import-in-the-middle" )
+
+for EXTERNAL_PACKAGE in "${EXTERNAL_PACKAGES[@]}"
+do
+  echo "Installing external package $EXTERNAL_PACKAGE ..."
+
+  PACKAGE_VERSION=$(npm query "#$EXTERNAL_PACKAGE" \
+    | grep version \
+    | head -1 \
+    | awk -F: '{ print $2 }' \
+    | sed 's/[",]//g')
+
+  echo "Resolved version of the external package $EXTERNAL_PACKAGE: $PACKAGE_VERSION"
+
+  npm install "$EXTERNAL_PACKAGE@$PACKAGE_VERSION" --prefix ./build/workspace/nodejs --production --ignore-scripts
+
+  echo "Installed external package $EXTERNAL_PACKAGE"
+done

lambda-layer/packages/layer/install-externals.sh

@@ -17,11 +17,13 @@
   },
   "scripts": {
     "clean": "rimraf build/*",
+    "install-externals": "./install-externals.sh",
     "lint": "eslint . --ext .ts",
     "lint:fix": "eslint . --ext .ts --fix",
-    "prepare": "npm run compile",
-    "compile": "tsc -p .",
-    "postcompile": "copyfiles -F 'node_modules/**' build/workspace/nodejs && copyfiles -f 'scripts/*' build/workspace && copyfiles -f 'build/src/*' build/workspace && cd build/workspace && bestzip ../layer.zip *"
+    "prepare": "npm run compile && npm run install-externals && npm run package",
+    "compile": "webpack",
+    "package": "cd build/workspace && bestzip ../layer.zip *",
+    "postcompile": "copyfiles -f 'scripts/*' build/workspace && copyfiles -f 'build/src/*' build/workspace"
   },
   "keywords": [
     "awsdistroopentelemetry",
@@ -34,5 +36,10 @@
   ],
   "dependencies": {
     "@aws/aws-distro-opentelemetry-node-autoinstrumentation": "file:../../../aws-distro-opentelemetry-node-autoinstrumentation/aws-aws-distro-opentelemetry-node-autoinstrumentation-0.5.0-dev0.tgz"
+  },
+  "devDependencies": {
+    "ts-loader": "^9.5.2",
+    "webpack": "^5.98.0",
+    "webpack-cli": "^6.0.1"
   }
 }

lambda-layer/packages/layer/package.json

@@ -29,7 +29,7 @@ _is_esm_handler() {
 }
 
 if _is_esm_handler || [[ ${HANDLER_IS_ESM} == true ]]; then
-  export NODE_OPTIONS="${NODE_OPTIONS} --import @aws/aws-distro-opentelemetry-node-autoinstrumentation/register --experimental-loader=@opentelemetry/instrumentation/hook.mjs"
+  export NODE_OPTIONS="${NODE_OPTIONS} --import /opt/wrapper.js --experimental-loader=import-in-the-middle/hook.mjs"
   export HANDLER_IS_ESM=true
 else
   export NODE_OPTIONS="${NODE_OPTIONS} --require /opt/wrapper.js"

lambda-layer/packages/layer/scripts/otel-instrument

@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.esm",
+  "compilerOptions": {
+    "rootDir": ".",
+    "outDir": "build",
+  },
+  "include": [
+    "src/**/*.ts",
+    "test/**/*.ts"
+  ]
+}

lambda-layer/packages/layer/tsconfig.webpack.json

@@ -1,13 +1,17 @@
 const path = require('path');
 
 module.exports = {
-  entry: './src/register.ts',
+  entry: './src/wrapper.ts',
   target: 'node',
   mode: 'production',
   externalsPresets: { node: true },
+  externals: [
+    'import-in-the-middle',
+    '@aws-sdk',
+  ],
   output: {
     path: path.resolve('./build/src'),
-    filename: 'register.js',
+    filename: 'wrapper.js',
     library: {
         type: 'commonjs2',
     }

aws-distro-opentelemetry-node-autoinstrumentation/webpack.config.js renamed to lambda-layer/packages/layer/webpack.config.js

@@ -0,0 +1,27 @@
+{
+    "compilerOptions": {
+      "moduleResolution": "node",
+      "module": "es2020",
+      "target": "es2020",
+      "allowUnreachableCode": false,
+      "allowUnusedLabels": false,
+      "declaration": true,
+      "declarationMap": true,
+      "esModuleInterop": true,
+      "forceConsistentCasingInFileNames": true,
+      "noEmitOnError": true,
+      "noFallthroughCasesInSwitch": true,
+      "noImplicitReturns": true,
+      "noUnusedLocals": true,
+      "pretty": true,
+      "sourceMap": true,
+      "strict": true,
+      "strictNullChecks": true,
+      "incremental": true,
+      "newLine": "LF"
+    },
+    "exclude": [
+      "node_modules"
+    ]
+  }
+