nodejs uploading pdf to S3 bucket corrupt file - node.js

Question

I am currently using aws-sdk to upload pdf files to bucket S3, like this:
function uploadFile (filePath, remoteFilename, cb) {
var fileBuffer = fs.createReadStream(filePath); // ex.: 'temp/longFileName.pdf'
fileBuffer.on('error', function(err) {
logger.warn('Failed reading local pdf file');
cb(err);
});
s3.upload({
Bucket: 'someBucketName',
Key: remoteFilename,
Body: fileBuffer
}, function (error, response) {
cb(error, { response, remoteFilename });
});
}
the problem is that sometimes the file gets uploaded with 0B size, sometimes it gets uploaded with the correct size, but when I download it, it is corrupt, and of course sometimes it is correctly uploaded and opens properly.
I read the pdf file locally from system file, and that pdf file is correct.
could somebody help me to fix this issue?
update
I am creating a pdf using pdfkit:
function createPdf (data, cb) {
var fs = require('fs');
var PDFDocument = require('pdfkit');
var filePath = 'temp/longFileName.pdf';
var pdf = new PDFDocument({
size: 'LEGAL',
info: {
Title: 'Tile of File Here',
Author: 'Some Author',
}
});
// Write stuff into PDF
pdf.text('Hello World');
// Stream contents to a file
pdf.pipe(
fs.createWriteStream(filePath)
)
.on('finish', function () {
console.log('PDF closed');
});
// Close PDF and write file.
pdf.end();
cb(null, {filePath})
}
once the callback in this function is called, i call the uploadFile function:
function doAll (someData, cb) {
createPdf(someData, function(err, data) {
if (err) console.log(err)
uploadFile(data.filePath, function(err,data) {
if (err) console.log(err)
console.log('finished')
cb(null, 'done');
return;
})
})
}

Answer 1

The problem is that you're calling the callback immediately instead of waiting for the file to be fully written. Your callback function should be inside .on('finish')
pdf.pipe(
fs.createWriteStream('./path/to/file.pdf')
)
.on('finish', function () {
console.log('PDF closed');
cb(null, 'finished'); // The callback should e in here
});
// Close PDF and write file.
pdf.end();