Lambda Function with Missing index.js

[Phil1216]

I have a serverless application with APIGateway, lambda, and Dynamodb. It involves both a REST API and a Websocket API with NodeJS lambda handlers. In my Websocket API I use an authorizer for the onConnect route. What I have noticed is that sometimes after I cdk deploy I get the following error in CloudWatch: "Error: Cannot find module 'index'\nRequire stack:\n- /var/runtime/index.mjs"

Sure enough, when I go to my authorizer lambda handler in the console (under the code tab), I see node_modules, package.json, and package-lock.json but no index.js. This issue only occurs with this one lambda function, which is very odd. I have two dozen other lambda functions and none of them have this particular problem.

I found that I can simply cdk deploy again to fix this issue. When I do so, I can see the index.js file in the lambda's code tab as expected. I am developing on Windows and I often get those annoying "Resource is busy or locked" errors, and I have a hunch my problem is related. The "Resource is busy or locked" error causes deploy to crash and I have to deploy again. Maybe that interrupts the process of making the index.js file, I don't know.

How should I go about debugging this? I don't want my application to have a random chance of blowing up when I cdk deploy.

[Phil1216]

I make my authorizer handler in a dedicated websocket stack like so:

const nodeJsFunctionProps: NodejsFunctionProps = {
  bundling: {
    externalModules: [
      "@aws-sdk/",
    ],
    nodeModules: [
      '@aws-lambda-powertools/logger', 
      '@aws-lambda-powertools/tracer',
      'aws-jwt-verify',
      '@aws-lambda-powertools/metrics'
    ],
  },
  depsLockFilePath: join(__dirname, '../resources/', 'package-lock.json'),
  environment: {
    //Environment variables
  },
  handler: "handler",
  runtime: Runtime.NODEJS_18_X,
  tracing: Tracing.ACTIVE,
  timeout: Duration.seconds(20),
}

const authorizerHandler = new NodejsFunction(this, "AuthorizerHandler", {
  entry: path.join(__dirname, `/../resources/handlers/websocket/Authorizer.ts`),
  ...nodeJsFunctionProps
});
WebsocketStack.createLogGroup(this, authorizerHandler, "LogGroup/AuthorizerHandler");

const authorizer = new WebSocketLambdaAuthorizer('Authorizer', authorizerHandler, { identitySource: ['route.request.header.Sec-WebSocket-Protocol'] });
this.webSocketApi = new WebSocketApi(this, 'ServerlessChatWebsocketApi', {
    apiName: 'Websocket API',
    connectRouteOptions: { integration: new WebSocketLambdaIntegration("ConnectIntegration", onConnectHandler), authorizer },
    disconnectRouteOptions: { integration: new WebSocketLambdaIntegration("DisconnectIntegration", onDisconnectHandler) },
    defaultRouteOptions: { integration: new WebSocketLambdaIntegration("DefaultIntegration", joinSessionHandler) },
    routeSelectionExpression: "$request.body.data.type"
});