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?

Answer 1

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

Answer 2

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() }());