How to authenticate in AWS SDK from segment?

I'm trying to call some AWS services from my segment function. To do that, I need to set the credentials for AWS, but I cannot find the way.

As you can see in the segment documentation, AWS is available. The problems are:

• I cannot use credential file (I only have one file in the segment funcion and cannot add more)
• I cannot use environment variables

I have also tried the following:

AWS.config.credentials.accessKeyId = "-";
AWS.config.credentials.secretAccessKey = "-";

That works locally with version 2.949.0 but not with v2.488.0 (the one provided by segment).

Any idea how can I authenticate? I have not found a way to authenticate using javascript code.

Actually, I'm configuring my AWS credentials using

AWS.config.update({
  region: 'us-east-1',
  accessKeyId: 'ACCESS_KEY',
  secretAccessKey: 'SECRET_KEY',
});

For example, to use S3 bucket

import * as AWS from 'aws-sdk';

    AWS.config.update({
      region: 'us-east-1',
      accessKeyId: 'ACCESS_KEY',
      secretAccessKey: 'SECRET_KEY',
    });


const s3 = new AWS.S3();

// and do some manipulations with s3

I'm not used the segment, but I guess it should work.