A .then doesn't run after the promise gets resolved on AWS Lambda

Question

Code:

var promiseResolve, promiseReject;    

function iterateRules(rules, params, i = 0) {

    CWevents.putRule(rules[i], function(err, data) {    // This is an async function with a callback
        if (err) console.log(err); promiseReject(err)

        responses++
        params['Lambda_invoke']['SourceArns'].push(data.RuleArn)

        if(responses == rules.length){ promiseResolve("Success"); console.log("Resolved")} 
        // After two responses are confirmed, this if does run and I get the "Resolved"
    })
    i++
    if(i < rules.length){
        setTimeout( function(){
            iterateRules(params['CW_rules']['Rules'], params, i)
        }, 50)
    }
}

new Promise((resolve, reject) => {
    resolve() 
// This part is added solely for the code to make sense, it's taken out of a 
// bigger script and lots of unnecessary data is removed 
})
.then((Item) => {
            return new Promise((resolve, reject) => {
                promiseReject = reject;
                promiseResolve = resolve;
                iterateRules(params['CW_rules']['Rules'], params)
            })
}) .then((res) => {
        console.log("This ran")
   })

The iterateRules function is supposed to run an asynchronous function multiple times, and resolve the Promise it's called in when the last response is acquired. The if(responses == rules.length) does run as expected and logs the "Resolved" in the console. Everything is successful, no errors.

Beneath is the context of this code, the iterateRules function is executed, but the .then that comes after, isn't. If I put a resolve() inside the promise directly, it does execute. What might be wrong with this script? I tried running a simple version of it that looks like this separately:

var res, rej;

function dude(){
    res()
}

new Promise((resolve, reject) => {
    res = resolve;
    dude()
}).then((dude) => {
    console.log("resolved")
})

And it does in fact work, so I'm very confused. What might cause the problem?

Answer 1

I would make iterateRules() return a promise (since it is asynchronous). I would also promisify the CWevents.putRule() function so you can accomplish some code like the below:

function iterateRules(rules, params) {
    return Promise.all(rules.map(rule => {
        return CWevents.putRule(rule)
    })).then((data) => {
        params['Lambda_invoke']['SourceArns'].push(data.RuleArn)
    })
}

Then your handler for iterateRules would become:

iterateRules(rules,params).then(()=>{
    // Do something...
})