s3_upload.js

// some code above

let tgz = tarball.pipe(gzip);

let creds = await auth.awsS3Credentials('read-write', 'taskcluster-raw-docs', 'testing');
aws.config.update(creds);

let s3obj = new aws.S3({params: {Bucket: 'taskcluster-raw-docs', Key: 'testing/latest.tar.gz'}});

await new Promise((resolve, reject) => {
      s3obj.upload({
        Body: tgz,
        ACL: 'public-read'}, (err, data) => {
          if (err) {
            console.log(`error! ${err}`);
            reject();
          } else {
            resolve();
          }
      });
});