Different Behavior Deploying AWS Lambda Standalone vs within an Application Stack - node.js

Question

Hi everybody and thanks for taking time to look at my issue/question.
I am getting different results when deploying my AWS Lambda stand-alone versus within an Application Stack.
I'm trying to connect to AWS Elasticache Redis from within my Lambda. I have .Net Core 3.1 Lambdas (using StackExchange.Redis) which can connect. But I also need to be able to connect from my Node.js Lambdas.
For the Node.js Lambdas, I'm using "node-redis" and "async-redis". I have two Lambdas which are essentially identical except that one is deployed in an Application Stack and the other is deployed as a stand-alone Lambda. Both Lambdas reference the same Lambda Layer (i.e. same "node_modules"), have the same VPC settings, the same Execution Role, and essentially the same code. So they've pushed it up to another group.
The stand-alone Lambda connects to Redis without issue. The Application Stack Lambda does not and exits processing before completing but without raising any error.
At first I thought I might just need to configure my Application Stack but I cannot find any information indicating we even can configure Application Stacks. So I'm at a loss.
The stand-alone Lambda:
exports.handler = async (event) => {
const asyncRedis = require("async-redis");
const redisOptions =
{
host: "XXXXXXXXX.XXXXX.XXXX.use2.cache.amazonaws.com",
port: 6379
}
console.log('A');
const client = asyncRedis.createClient(redisOptions);
console.log(client);
console.log('B');
const value = await client.get("Key");
console.log('C');
console.log(value);
console.log('D');
console.log(client);
};
The output of this function is essentially:
A
{RedisClient} --> the "client" object --> Shows connected = false
B
C
{ Correct Data From Redis }
D
{RedisClient} --> the "client" object --> Shows connected = true
The Application Stack Lambda:
async function testRedis2(event, context) {
console.log('In TestRedis2');
const asyncRedis = require("async-redis");
const redisOptions =
{
host: "XXXXXXXXX.XXXXX.XXXX.use2.cache.amazonaws.com",
port: 6379
}
console.log('A');
const client = asyncRedis.createClient(redisOptions);
console.log(client);
console.log('B');
var value = await client.get("Key");
console.log('C');
console.log(value);
console.log('D');
console.log(client);
}
module.exports = {
testRedis2
};
The output of this function is essentially:
In TestRedis2
A
{RedisClient} --> the "client" object --> Shows connected = false
B
I don't understand why these don't perform identically. And I don't get why I don't see further entries in the output.
Has anyone else experienced issues connecting to VPC resources from within an Application Stack?
Thanks

Answer 1

I stumbled across the answer through extensive trial and error. It may be obvious to Node/js developers but, just in case another Javascript/Node newbie has the same issue, I'll post the answer here.
The import/require and creation of the client must be at the top of the module. Not in the function itself.
So, the following does work in my application stack:
const asyncRedis = require("async-redis");
const redisOptions = {
host: "XXXXXXXXX.XXXXX.XXXX.use2.cache.amazonaws.com",
port: 6379
};
const client = asyncRedis.createClient(redisOptions);
async function redisGet(key: string){
// console.log('In redisGet');
return await client.get(key);
}