How to use Async and Await with AWS SDK Javascript

Question

I am working with the AWS SDK using the KMS libary. I would like to use async and await instead of callbacks.

import AWS, { KMS } from "aws-sdk";

this.kms = new AWS.KMS();

const key = await this.kms.generateDataKey();

However this does not work, when wrapped in an async function.

How can i use async and await here?

`await` requires a promise; that takes a callback. – SLaks Jul 13 '18 at 15:20 — SLaks, Jul 13 '18 at 15:20

hoangdv · Accepted Answer · 2019-06-23T17:22:34.170

117

If you are using aws-sdk with version > 2.x, you can tranform a aws.Request to a promise with chain .promise() function. For your case:

  try {
    let key = await kms.generateDataKey().promise();
  } catch (e) {
    console.log(e);
  }

the key is a KMS.Types.GenerateDataKeyResponse - the second param of callback(in callback style).

The e is a AWSError - The first param of callback func

note: await expression only allowed within an async function

edited Jun 23 '19 at 17:22

answered Jul 13 '18 at 15:34

hoangdv

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How can one access `key` outside of the try statement? – mbspark Mar 14 '20 at 23:22
@mbspark you can create `key` variable at first, outside of the `try` block. But, why? – hoangdv Mar 15 '20 at 03:44
I wanted to use `key` elsewhere in the program. I did end up figuring out what I was trying to do in a different way, though. – mbspark Mar 15 '20 at 17:01
life-saver .... – Muhamad Rafi Pamungkas May 20 '21 at 11:25

zero298 · Answer 2 · 2018-07-13T15:38:21.590

await requires a Promise. generateDataKey() returns a AWS.Request, not a Promise. AWS.Request are EventEmitters (more or less) but have a promise method that you can use.

import AWS, {
  KMS
} from "aws-sdk";

(async function() {
  const kms = new AWS.KMS();
  const keyReq = kms.generateDataKey()
  const key = await keyReq.promise();

  // Or just:
  // const key = await kms.generateDataKey().promise()
}());

How to use Async and Await with AWS SDK Javascript

2 Answers2

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