Support for v4 pre-signed URLs is in the works, but you can use v2 signatures with the AWS SDK as well. Depending on the version of the SDK you have installed, it maybe in use by default. (The latest version should when using a custom endpoint. Some older versions used v4 by default everywhere, but this change was reverted in version 2.152.0)

If needed, you can force the signature version when configuring your client:

const s3 = new AWS.S3({
    endpoint: spacesEndpoint,
    accessKeyId: 'YOURACCESSKEY',
    secretAccessKey: 'YOURSECRETKEY',
    signatureVersion: 'v2'
});

Here’s a quick example for generating a pre-signed putObject URL with a v2 signature:

const AWS = require('aws-sdk')

const spacesEndpoint = new AWS.Endpoint('nyc3.digitaloceanspaces.com');
const s3 = new AWS.S3({
    endpoint: spacesEndpoint,
    accessKeyId: 'YOURACCESSKEY',
    secretAccessKey: 'YOURSECRETKEY',
    signatureVersion: 'v2'
});

var space = 'my-space-name'
var key = 'my-file-name'
var expireSeconds = 60 

s3.getSignedUrl('putObject', {
    Bucket: space,
    Expires: expireSeconds,
    Key: key
}, function (err, url) {
    console.log(url);
});

@vallelungabrian here’s a tutorial recently published on the topic: https://www.digitalocean.com/community/tutorials/how-to-upload-a-file-to-object-storage-with-node-js