AWS Lambda S3 GET/POST - SignatureDoesNotMatch error - amazon-s3

Question

I have had a Lambda node.js function up and running for about 6 months without any issue. The function simply takes a object and copies it from one bucket to another.
Today, I have started getting:
"SignatureDoesNotMatch: The request signature we calculated does not
match the signature you provided. Check your key and signing method."
The code I am using is pretty simple, any suggestions on how I could fix this?
var aws = require('aws-sdk');
var s3 = new aws.S3({apiVersion: '2006-03-01'});
exports.handler = function(event, context) {
var to_bucket = 'my_to_bucket/test';
var from_bucket = event.Records[0].s3.bucket.name;
var key = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " "));
var size = Math.floor(event.Records[0].s3.object.size / 1024);
s3.getObject({Bucket: from_bucket, Key: key}, function(err, data) {
if (err) {
// send a webhook
}
else {
s3.putObject({Bucket: to_bucket, Key: key, Body: data.Body, ContentType: data.ContentType},
function(err, data) {
if (err) {
// send a webhook
}
else {
// send a webhook
}
});
} // end else
}); // end getobject
};
UPDATE:
I have discovered that if sending to a bucket, it works fine. If I sent to any subfolder of the same bucket, it fails. I do send to a subfolder and simplified the code above initially, but I've updated it to show a subfolder in the to_bucket.

Answer 1

I found a fix for this. After realising it was due to the folder inside the bucket, and not just sending to a bucket root, I searched and found the following post: https://github.com/aws/aws-sdk-go/issues/562
It looks like the bucket should not include the subfolder, instead the key should. Why this has worked until now is a mystery. Here is the replacement code for above:
var aws = require('aws-sdk');
var s3 = new aws.S3({apiVersion: '2006-03-01'});
exports.handler = function(event, context) {
var to_bucket = 'my_to_bucket';
var from_bucket = event.Records[0].s3.bucket.name;
var key = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " "));
var size = Math.floor(event.Records[0].s3.object.size / 1024);
s3.getObject({Bucket: from_bucket, Key: key}, function(err, data) {
if (err) {
// send a webhook
}
else {
key = 'subfolder/' + key;
s3.putObject({Bucket: to_bucket, Key: key, Body: data.Body, ContentType: data.ContentType},
function(err, data) {
if (err) {
// send a webhook
}
else {
// send a webhook
}
});
} // end else
}); // end getobject
};