Receiving null from lambda

[matttm]

I am just trying to run express on a lambda and I keep getting null returned.

Do I need an API gateway for this to work?

// app.js
const express = require('express');
const v1 = require('./versions/v1/v1.routes');

const app = express();
app.use(express.urlencoded({ extended: true }));
app.use(express.json());

app.use('/api/v1', v1);

app.get('/', async (req, res) => {
    console.log('the code is being hit');
    return res.json({ lambda: true });
});

module.exports = app;

Lambda code

// index.js
const app = require('app');
const serverless = require('serverless-http');

const handler = serverless(app, { provider: 'aws' });
module.exports.handler = async (context, req) => {
    const tmp = await handler(context, req);
    console.log('tmp', tmp);
    context.res = tmp;
}

Test event logs

Test Event Name
time

Response
null

Function Logs
START RequestId: 5a562aa1-bdfb-459c-8794-fcfaf8c775fc Version: $LATEST
2023-02-19T13:08:21.195Z	5a562aa1-bdfb-459c-8794-fcfaf8c775fc	INFO	the code is being hit
2023-02-19T13:08:21.276Z	5a562aa1-bdfb-459c-8794-fcfaf8c775fc	INFO	tmp {
  statusCode: 200,
  headers: {
    'x-powered-by': 'Express',
    'content-type': 'application/json; charset=utf-8',
    'content-length': '15',
    etag: 'W/"f-CoGLJRqFBGAO5E78DxCjgBIQ/g4"'
  },
  isBase64Encoded: false,
  body: '{"lambda":true}'
}
END RequestId: 5a562aa1-bdfb-459c-8794-fcfaf8c775fc
REPORT RequestId: 5a562aa1-bdfb-459c-8794-fcfaf8c775fc	Duration: 170.34 ms	Billed Duration: 171 ms	Memory Size: 128 MB	Max Memory Used: 73 MB	Init Duration: 289.97 ms

Request ID
5a562aa1-bdfb-459c-8794-fcfaf8c775fc

dependencies

  "dependencies": {
    "express": "^4.18.2",
    "serverless-http": "^3.1.1"
  }

[akshay-nm]

I am also receiving null as a response from my aws lambda. The express app is not returning null.

[whenmoon]

Yes, I am also experiencing this. Express app works fine locally, but routes return null when deployed

[emyriounis]

It happened to me, too. When I switch from nodejs16.x to nodejs18.x

[akshay-nm]

guys, this is still an issue i am facing
I checked the logs, my express code is running as i can see logs for the lambda function
but api gateway just returns 200 status code with null, no matter what my lambda does

versions:

		"serverless-http": "^3.2.0",
		"express": "^4.18.2",
		"node": "20.6.1",

is there anything I can do to help?

[akshay-nm]

Fixed this!!

@matttm you need to return the res from your handler.
doing context.res = tmp doesn't cut it.
you need to return tmp
cc @whenmoon

module.exports.handler = async (context, req) => {
    const tmp = await handler(context, req);
    console.log('tmp', tmp);
    // context.res = tmp;
    return tmp 
}