lambda-trigger-pre-authentication.js - AWS Code Sample


/* Copyright, Inc. or its affiliates. All Rights Reserved. SPDX-License-Identifier: Apache-2.0 ABOUT THIS NODE.JS EXAMPLE: This example works with AWS SDK for JavaScript version 3 (v3), which is pending release. The preview version of the SDK is available at This example is in the 'AWS SDK for JavaScript v3 Developer Guide' at Purpose: lambda-trigger-pre-authentication.js is an example AWS Lambda function that prevents users from a specific user pool app client from signing in to the user pool. Running the code: 1. On the AWS Lambda service dashboard, choose Create function. 2. On the Create function page, name the function, and choose Create function. 3. Copy and paste the code into the index.js file in the editor, and save the function. 4. Open the Amazon Cognito service. 5. Choose Manage user pools. 6. Choose the user pool you want to add the trigger to. (If you don't have a user pool, create one.) 7. In General Settings, choose Triggers. 8. In the Pre authentication pane, select the Lambda function. */ exports.handler = async (event, context) => { try { if ( event.callerContext.clientId === "user-pool-app-client-id-to-be-blocked" ) { const error = new Error( "Cannot authenticate users from this user pool app client" ); } } catch (err) { // Return to Amazon Cognito return err; } };