node.js - How to get the URL of a file on AWS S3 using aws-sdk?

Question

I'm using an AWS Lambda function to create a file and save it to my bucket on S3, it is working fine. After executing the putObject method, I get a data object, but it only contains an Etag of the recently added object.

s3.putObject(params, function(err, data) {
    // data only contains Etag
});

I need to know the exact URL that I can use in a browser so the client can see the file. The folder has been already made public and I can see the file if I copy the Link from the S3 console.

I tried using getSignedUrl but the URL it returns is used for other purposes, I believe.

Thanks!

Answer 1

The SDKs do not generally contain a convenience method to create a URL for publicly-readable objects. However, when you called PutObject, you provided the bucket and the object's key and that's all you need. You can simply combine those to make the URL of the object, for example:

• https://bucket.s3.amazonaws.com/key

So, for example, if your bucket is pablo and the object key is dogs/toto.png, use:

• https://pablo.s3.amazonaws.com/dogs/toto.png

Note that S3 keys do not begin with a / prefix. A key is of the form dogs/toto.png, and not /dogs/toto.png.

For region-specific buckets, see Working with Amazon S3 Buckets and AWS S3 URL Styles. Replace s3 with s3.<region>.amazonaws.com or s3-<region>.amazonaws.com in the above URLs, for example:

• https://seamus.s3.eu-west-1.amazonaws.com/dogs/setter.png (with dot)
• https://seamus.s3-eu-west-1.amazonaws.com/dogs/setter.png (with dash)

If you are using IPv6, then the general URL form will be:

• https://BUCKET.s3.dualstack.REGION.amazonaws.com

For some buckets, you may use the older path-style URLs. Path-style URLs are deprecated and only work with buckets created on or before September 30, 2020. They are used like this:

• https://s3.amazonaws.com/bucket/key
• https://s3.amazonaws.com/pablo/dogs/toto.png
• https://s3.eu-west-1.amazonaws.com/seamus/dogs/setter.png
• https://s3.dualstack.REGION.amazonaws.com/BUCKET

Currently there are TLS and SSL certificate issues that may require some buckets with dots (.) in their name to be accessed via path-style URLs. AWS plans to address this. See the AWS announcement.

Note: General guidance on object keys where certain characters need special handling. For example space is encoded to + (plus sign) and plus sign is encoded to %2B. Also here.