Selling partner Aws Sign4 wrong calcualation for vendor - amazon-web-services

Question

I am using the API method "Directly making calls to Selling partner APIs".
I followed all the steps correctly:
Request a Login with Amazon access token - This API is working successfully & Getting access token.
Construct a Selling Partner API URI - After that, I took access_token and pass into options header request- 'x-amz-access-token'.
Add headers to the URI
Create and sign your request
After calling API https://sellingpartnerapi-eu.amazon.com/vendor/orders/v1/purchaseOrders
I am getting a signature response with error-
The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method.
My code:-
let options = {
service: 'execute-api',
region:'eu-west-1',
method: 'GET',
url: 'https://sellingpartnerapi-eu.amazon.com/vendor/orders/v1/purchaseOrders/?includeDetails=true&createdBefore=2020-04-20T14:00:00-08:00&createdAfter=2020-04-14T00:00:00-08:00',
headers: {
'Content-Type': 'application/json',
'host':'sellingpartnerapi-eu.amazon.com',
'x-amz-access-token':access_token,
'x-amz-date': '20200604T061745Z',
'user-agent':'My App(Language=Node.js;Platform=Windows/10)'
}
}
let signedRequest = aws4.sign(options,
{
secretAccessKey: secretAccessKey,
accessKeyId: accessKeyId,
})
console.dir("signedRequest");
console.dir(signedRequest);
delete signedRequest.headers['Host']
delete signedRequest.headers['Content-Length']
request(awsres, function(err, res, body) {
console.dir("err");
console.dir(err);
console.dir("res");
console.dir(res.body);
});

Answer 1

I would imagine the signature is calculated the same way it is calculated in other AWS services.
Signature Version 4 signing process docs.
#aws-sdk/signature-v4-node -- official AWS SDK v3 signature package, but v3 is very much in beta. But I imagine they have figured out the signature package, as it wouldn't be possible to interact with the API without it.
aws-signature-v4 NodeJS package