How do I create a signed public 'share' URL similar to the 'Quick Share' option in Spaces?

October 16, 2017 1.4k views
Applications Node.js Ubuntu

How do I create a signed public 'share' URL similar to the 'Quick Share' option in Spaces?

I am writing an application in Node.JS and would like to return a temporary access URL to the user so they can access a file stored in spaces for a set amount of time. The Space itself is set to Private and the files are all Private as well, so just giving a direct URL to them isn't possible.

The DigitalOcean UI already has this "Quick Share" feature, but there doesn't seem to be any documentation about what its doing to create that URL and I cant figure out how to sign the request correctly to generate one myself.

The URL parameters in question are, AWSAccessKeyId, Expires and Signature. The AWSAccessKeyId and Expires seem simple enough, but how do I go about calculating the signature?

2 Answers
asb MOD October 16, 2017
Accepted Answer

The AWS signature formats can be a bit complicated. Though the reason for making Spaces compatible with the S3 API is that there are already quite a few tools that can work with it. If you're working with Node, I'd encourage you to use one of the existing libraries.

The aws-sdk-js can help generate these "pre-signed" URLs. Here's a quick basic example of it's usage:

const AWS = require('aws-sdk')

const spacesEndpoint = new AWS.Endpoint('nyc3.digitaloceanspaces.com');
const s3 = new AWS.S3({
    endpoint: spacesEndpoint,
    accessKeyId: 'ACCESSKEY',
    secretAccessKey: 'SECRETKEY'
});

const bucket = 'my-bucket-name'
const key = 'my-file-name.ext'
const expireSeconds = 60 * 5

const url = s3.getSignedUrl('getObject', {
    Bucket: bucket,
    Key: key,
    Expires: expireSeconds
})

console.log(url)

I hope no one minds me ressurecting this thread...

Does the approach above, where you use the existing AWS libraries to generate a URL, mean you could just use that S3 URL and transform it according to a certain pattern (ex. substitute AWS domain for DO domain etc) and use that new URL to download/upload objects from/to Spaces?

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