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AWS AppSync Chat App CDK Backend

This repo is part of an official AWS Blog post that showcases how to create a serverless, real-time backend that integrates with a frontend application.

Services Used

service diagram

Amazon Cognito

The lib/authStack.ts file creates the following services

  • Cognito user pool
  • Cognito user pool group (if specified)
  • Cognito identity pool

🗒️ The identity pool helps in providing IAM permission access to both authenticated and unauthenticated users as well as AWS services such as Amazon S3.

AWS Lambda

The lib/functions directory contains a postConfirmationTrigger folder. The Lambda function in this folder adds a user to DynamoDB after a user signs up through our Cognito service.

Amazon Simple Storage Service (Amazon S3)

The lib/fileStorage.ts file creates an Amazon S3 bucket and comes configured with managed polices that are in line with what the Amplify Storage library uses as acceptable defaults.

AWS AppSync API

Thelib/apiStack.ts file creates an AWS AppSync API that is based on a Todo application.

Note that this stack comes preconfigured with the following:

  • A sample graphql schema
  • User pool authorization
  • API Key authorization
  • IAM authorization
  • DynamoDB as a datasource

In addition, this package makes use of the @aws-cdk/aws-appsync-alpha npm package for easily creating the request and response mapping templates.

Amazon DynamoDB API

The lib/databaseStack.ts file creates a single DynamoDB table that is used as a datasource for the AWS AppSync API above.

Integrating with a frontend

For a full walkthrough on how one might integrate the output from these stacks into a frontend application that makes use of AWS Amplify libraries, refer to this fullstack guide.

Useful commands

  • npm run build compile typescript to js
  • npm run watch watch for changes and compile
  • cdk deploy deploy this stack to your default AWS account/region
  • cdk diff compare deployed stack with current state
  • cdk synth emits the synthesized CloudFormation template

Security

See CONTRIBUTING for more information.

License

This library is licensed under the MIT-0 License. See the LICENSE file.

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  • TypeScript 71.3%
  • JavaScript 16.1%
  • Velocity Template Language 12.6%