Save html file from S3 and set is as content to puppeteer - node.js

Question

I have a Lambda function in AWS which fetches an html file from S3 after a PUT event in the bucket. The Lambda function fetches it and saves it in /tmp/tml and then loads it again so as to be set as content in puppeteer and produce a pdf. My code is the following:
const chromium = require("#sparticuz/chrome-aws-lambda");
const AWS = require('aws-sdk');
const fs = require('fs');
const path = require('path');
const IAM_USER_KEY = "asdfadsfasd";
const IAM_USER_SECRET = "asdfdsafasdfds";
const s3bucket = new AWS.S3({
accessKeyId: IAM_USER_KEY,
secretAccessKey: IAM_USER_SECRET
});
const copyRecursiveSync = function (src, dest) {
const exists = fs.existsSync(src);
const stats = exists && fs.statSync(src);
const isDirectory = exists && stats.isDirectory();
if (isDirectory) {
if (!fs.existsSync(dest)) {
fs.mkdirSync(dest);
}
fs.readdirSync(src).forEach(function (childItemName) {
copyRecursiveSync(path.join(src, childItemName), path.join(dest, childItemName));
});
} else {
fs.copyFileSync(src, dest);
}
};
function uploadObjectToS3Bucket(objectName, objectData) {
const params = {
Bucket: 'asdfasdfsadf',
Key: objectName,
Body: objectData,
ContentType: 'application/pdf'
};
s3bucket.upload(params, function(err, data) {
if (err) throw err;
console.log('File uploaded successfully');
});
}
function downloadFromS3(bucket, key, location){
const params = {
Bucket: bucket,
Key: key,
};
const rs = s3bucket.getObject(params).createReadStream();
const ws = fs.createWriteStream(location);
rs.pipe(ws);
return true;
}
exports.handler = async (event, context, callback) => {
copyRecursiveSync('mylayerfiles/tml/', '/tmp/tml/');
console.log('Assets copied to /tmp/tml \n');
const bucket = event.Records[0].s3.bucket.name;
const key = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, ' '));
const html_file_name = key.split('/').pop();
console.log('Launching browser');
const browser = await chromium.puppeteer.launch({ headless: true, executablePath: await chromium.executablePath, args: ['--no-sandbox', '--disable-setuid-sandbox','--disable-web-security',
'--disable-dev-shm-usage',
'--single-process']});
console.log("Browser launched");
const page = await browser.newPage();
console.log(`Saving in /tmp/tml/${html_file_name}`);
downloadFromS3(bucket, key, `/tmp/tml/${html_file_name}`);
const bufferFile = async (relPath) => {
const data = fs.readFileSync(relPath, { encoding: 'utf8' }, function (err) {
if (err) {
console.log("readfile failed: " + err);
return 400;
} else {
console.log("readfile succeeded");
}
});
return data;};
const BUFFER = await bufferFile(`/tmp/tml/${html_file_name}`);
console.log('html file read from /tmp');
await page.setContent(content);
console.log('html set as content');
const pdfConfig = {
printBackground: true,
landscape: false,
width: "338.63mm",
height: "190.5mm"
};
await page.emulateMediaType('screen');
const pdf = await page.pdf(pdfConfig);
console.log('Uploading to S3 bucket');
const key_to_save = key.replace(/\.[^/.]+$/, ".pdf");
console.log(key_to_save);
uploadObjectToS3Bucket(key_to_save, pdf);
console.log('Uploaded to S3 bucket');
await browser.close();
console.log('Browser closed');
return 200;}
catch (err) {
console.log(err);
return 500}
};
However, the problems I'm facing are two:
The file sometimes is not written in /tmp/tml for some reason(!)
If written, it is not read correctly and subsequently, the setcontent() function does not product the proper pdf.