Making a node-fetch POST request with file as payload - node.js

Question

first time poster, excited to have a community to collaborate with here!
So here's my situation. I'm using Node to put together an automation for my company's compliance - taking reports from our MDM server and posting them to our compliance platform (Tugboat Logic). The idea is to have it deployed on a recurring basis via AWS Lambda. The basic logic is this: getToken fetches an auth token which is then passed to getReports. getReports loops through an array of endpoints to get reports from the MDM and then passes those along to fileReport - which then posts that data to the endpoint.
The problem is that the final endpoint needs a file as the payload (sample POST request below). I managed to get the whole fetch chain working by using fs writeFile/readFile (and a delay), and while that worked, it doesn't translate well into a Lambda environment. Ideally, I want to just take the payload from getReports (which comes through as JSON but can also be accepted as text) and push it straight to the endpoint. Any help on how I could clean up this code would be appreciated!
Here's the bit giving me the most trouble (from the last file)
form.append('file', x, `${reportsArray[i].name}.json`);
// Sample post request for final endpoint
curl -v --user <provided-username>:<given-password> \
-H "X-API-KEY: <given-x-api-key>" \
-F "collected=<date-of-evidence>" -F "file=#<local_filename_csv>;type=text/csv" \
<given-collector-url>
//getReports.js accepts a token from an earlier function and takes fileReport as the cb
function getReports(token, cb) {
const headers = {
method: 'GET',
headers: {
'accept': 'application/json',
'Authorization': `Bearer ${token}`
},
redirect: 'follow'
}
for (let i = 0; i < reportsArray.length; i++) {
fetch(reportsArray[i].source, headers)
.then(res => res.json())
// writeFile leftover from successful deploy
/*.then(data => fs.writeFile(`./reports/${reportsArray[i].name}.json`, data, function (err) {
if (err) throw err;
}))*/
.then(res => cb(i, res))
.catch(error => console.log('error', error))
}
};
//fileReport.js - i identifies the right endpoint from the imported array and sets filename. x is the JSON payload passed down from getReports
function fileReport(i, x) {
const form = new FormData();
form.append('collected', getTimestamp());
form.append('file', x, `${reportsArray[i].name}.json`);
fetch(`${reportsArray[i].dest}`, {
method: 'POST',
headers: {
'X-API-KEY': `${process.env.TUGBOAT_X_API_KEY}`,
'Authorization': 'Basic ' + btoa(`${process.env.TUGBOAT_USERNAME}:${process.env.TUGBOAT_PASSWORD}`)
},
body: form
});
};