AWS-serverless-express never resolving with promises - node.js

Question

can anyone shed light on my issue opened at the aws-serverless-express repo on github? https://github.com/awslabs/aws-serverless-express/issues/276
I am trying to run my previous express.js server using the aws-serverless-express package. When running without any special options I resolve, but the promises in the chain are never respected, meaning I dont execute all things in the event loop.
If I run the serverlessexpress with 'PROMISE' flag, I execute all my promises, but the program never resolves and times out after the maximum time set.
I even started a new project as per the example in that repo, same result.
My main executing file (index.js) when resolving but not respecting my promises
const awsServerlessExpress = require('aws-serverless-express')
const app = require('./app.js')
const server = awsServerlessExpress.createServer(app, null)
exports.handler = (event, context) => {
return awsServerlessExpress.proxy(server, event, context)
}
My main executing file (index.js) when NOT resolving, but respecting my promises
const awsServerlessExpress = require('aws-serverless-express')
const app = require('./app.js')
const server = awsServerlessExpress.createServer(app, null)
exports.handler = (event, context) => {
return awsServerlessExpress.proxy(server, event, context, 'PROMISE')
}
I also tried this:
const awsServerlessExpress = require('aws-serverless-express')
const app = require('./app.js')
const server = awsServerlessExpress.createServer(app, null)
exports.handler = (event, context) => {
return awsServerlessExpress.proxy(server, event, context, 'PROMISE').promise
}
My express server file (app.js)
const express = require('express')
const bodyParser = require('body-parser')
const awsServerlessExpressMiddleware = require('aws-serverless-express/middleware')
const app = express()
const router = express.Router()
router.use(bodyParser.json())
router.use(bodyParser.urlencoded({ extended: true }))
router.use(awsServerlessExpressMiddleware.eventContext())
router.get('/', (req, res) => {
res.render('index', {
apiUrl: req.apiGateway ? `https://${req.apiGateway.event.headers.Host}/${req.apiGateway.event.requestContext.stage}` : 'http://localhost:3000'
})
})
router.get('/users', (req, res) => {
res.json(users)
})
const users = [{
id: 1,
name: 'Joe'
}, {
id: 2,
name: 'Jane'
}]
function myFunc () {
console.log('hey')
}
setTimeout(myFunc, 3000)
app.use('/', router)
module.exports = app

Answer 1

Make sure you are setting context.callbackWaitsForEmptyEventLoop to false
read more about it here https://docs.aws.amazon.com/lambda/latest/dg/nodejs-context.html

Answer 2

The issue was regarding my testing tool:
https://www.npmjs.com/package/run-local-lambda
When I spoke with the AWS Support, they told me to use:
sam local invoke "Test" -e event.json
With a event.json file that includes the following:
{
"httpMethod": "OPTIONS",
"//body": "{\"name\": \"Sam\"}",
"path": "/api/auth",
"resource": "/{proxy+}",
"queryStringParameters": {},
"pathParameters": {
"proxy": "users"
},
"headers": {
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Accept-Encoding": "gzip, deflate, sdch, br",
"Accept-Language": "en-US,en;q=0.8",
"CloudFront-Forwarded-Proto": "https",
"CloudFront-Is-Desktop-Viewer": "true",
"CloudFront-Is-Mobile-Viewer": "false",
"CloudFront-Is-SmartTV-Viewer": "false",
"CloudFront-Is-Tablet-Viewer": "false",
"CloudFront-Viewer-Country": "US",
"Content-Type": "application/json",
"Host": "xxxxxxxxxx.execute-api.us-east-1.amazonaws.com",
"Upgrade-Insecure-Requests": "1",
"User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36",
"Via": "1.1 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.cloudfront.net (CloudFront)",
"X-Amz-Cf-Id": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxx==",
"X-Forwarded-For": "11.111.111.111, 11.111.111.111",
"X-Forwarded-Port": "111",
"X-Forwarded-Proto": "http",
"x-apigateway-event": "hej"
},
"requestContext": {
"accountId": "111111111111",
"resourceId": "xxxxxx",
"stage": "prod",
"requestId": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
"identity": {
"cognitoIdentityPoolId": "",
"accountId": "",
"cognitoIdentityId": "",
"caller": "",
"apiKey": "",
"sourceIp": "11.111.111.111",
"cognitoAuthenticationType": "",
"cognitoAuthenticationProvider": "",
"userArn": "",
"userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36",
"user": ""
},
"resourcePath": "/{proxy+}",
"httpMethod": "GET",
"apiId": "xxxxxxxxxx"
}
}
And a template file to use just for testing that looks like this:
AWSTemplateFormatVersion : '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description:
A test project
Resources:
Test:
Type: AWS::Serverless::Function
Properties:
Runtime: nodejs10.x
Handler: index.handler
Timeout: 10
Environment:
Variables:
NODE_ENV: "test"
DB_NAME: "dbname"
DB_USER: "dbuser"
DB_PASSWORD: "secret"
DB_URL: "dburl"
The code I use looks like this in the handler:
'use strict'
const awsServerlessExpress = require('aws-serverless-express')
const app = require('./main.js')
const server = awsServerlessExpress.createServer(app, null)
exports.handler = (event, context) => {
return awsServerlessExpress.proxy(server, event, context,'PROMISE').promise
}
Then my code executed wonderful with no timeouts ever.