AWS Lambda NodeJS writing to S3 behaves differently on local and sever

Question

I created a NodeJS Lambda function with Serverless. It reads from a DynamoDB table and writes the data to a S3 bucket.

Here\'s my handler.js: (showing the af

Answer 1

Your outer promise is finishing without waiting the writeToBuffer promise.

Try changing:

workbook.writeToBuffer().then(...

To:

return workbook.writeToBuffer().then(...

You should do the same to the S3 upload call:

return S3.upload(params).promise().then(data => {
        callback(null, response(200, res));
});

I would also recommend you rewrite your code using the async / await syntax, so it is easier to read and understand.