How to use Async and Await with AWS SDK Javascript

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()
}());

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

As of 2021 I'd suggest to use AWS SDK for JavaScript v3. It's a rewrite of v2 with some great new features

sample code:

const { KMSClient, GenerateDataKeyCommand } = require('@aws-sdk/client-kms');

const generateDataKey = async () => {
  const client = new KMSClient({ region: 'REGION' });
  const command = new GenerateDataKeyCommand({ KeyId: 'KeyId' });
  const response = await client.send(command);
  return response;
};

AWS SDK for JavaScript v3 new features

• modular architecture with a separate package for each service
• First-class TypeScript support
• New middleware stack