lambda.invoke call through Node AWS SDK is timing out at 5 minutes while Lambda is completing under 4 minutes - node.js

Question

I have a Lambda function that is set to timeout at 5 minutes, and occasionally when I invoke the function using the node SDK, I am getting a timeout error after 5 minutes.
However, when I have checked the CloudWatch logs after getting the client-side error, and am seeing the function successfully complete after ~3:30 minutes of execution time.
I have also noticed that the client side will log the timeout 2 minutes before the CloudWatch logs read that the function completed (ie, client side error timestamps at 4:08 and the CloudWatch successful end timestamps at 4:10), but I am assuming that is a lag between log writes, not run time. Thought I would mention it just in case that is something worth thinking more about.
From what I can tell, when the function runs under two minutes, it is consistently getting a positive response.
Code looks like this:
let aws_config = new AWS.Config({
region: 'us-east-1',
credentials: credentials,
httpOptions: {
proxy: process.env.HTTP_PROXY,
timeout: 300000
}
})
var lambda = new AWS.Lambda(aws_config);
lambda.invoke(params, (err, data: Result) => {
...
}
Error looks like this:
{ TimeoutError: Connection timed out after 300000ms
at ClientRequest.<anonymous> (.../node_modules/aws-sdk/lib/http/node.js:83:34)
at Object.onceWrapper (events.js:273:13)
at ClientRequest.emit (events.js:182:13)
at ClientRequest.EventEmitter.emit (domain.js:442:20)
at Socket.emitRequestTimeout (_http_client.js:661:40)
at Object.onceWrapper (events.js:273:13)
at Socket.emit (events.js:182:13)
at Socket.EventEmitter.emit (domain.js:442:20)
at Socket._onTimeout (net.js:449:8)
at ontimeout (timers.js:425:11)
message: 'Connection timed out after 300000ms',
code: 'TimeoutError',
time: 2018-10-05T20:08:35.719Z,
region: 'us-east-1',
hostname: 'lambda.us-east-1.amazonaws.com',
retryable: true } 'TimeoutError: Connection timed out after 300000ms\n at ClientRequest.<anonymous> (.../node_modules/aws-sdk/lib/http/node.js:83:34)\n at Object.onceWrapper (events.js:273:13)\n at ClientRequest.emit (events.js:182:13)\n at ClientRequest.EventEmitter.emit (domain.js:442:20)\n at Socket.emitRequestTimeout (_http_client.js:661:40)\n at Object.onceWrapper (events.js:273:13)\n at Socket.emit (events.js:182:13)\n at Socket.EventEmitter.emit (domain.js:442:20)\n at Socket._onTimeout (net.js:449:8)\n at ontimeout (timers.js:425:11)'

Answer 1

Have you looked into
context.callbackWaitsForEmptyEventLoop = false;
Here'e a related SO posting:
Why does AWS Lambda function always time out?