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Update: We have released an updated and more feature-rich Websocket chat application sample using AWS CDK that you can find here.

This is the code and template for the simple-websocket-chat-app. There are three functions contained within the directories and a SAM template that wires them up to a DynamoDB table and provides the minimal set of permissions needed to run the app:

├──                   <-- This instructions file
├── onconnect                   <-- Source code onconnect
├── ondisconnect                <-- Source code ondisconnect
├── sendmessage                 <-- Source code sendmessage
└── template.yaml               <-- SAM template for Lambda Functions and DDB

Deploying to your account

You have two choices for how you can deploy this code.

Serverless Application Repository

The first and fastest way is to use AWS's Serverless Application Respository to directly deploy the components of this app into your account without needing to use any additional tools. You'll be able to review everything before it deploys to make sure you understand what will happen. Click through to see the application details.

AWS CLI commands

If you prefer, you can install the AWS SAM CLI and use it to package, deploy, and describe your application. These are the commands you'll need to use:

sam deploy --guided

aws cloudformation describe-stacks \
    --stack-name simple-websocket-chat-app --query 'Stacks[].Outputs'

Note: .gitignore contains the samconfig.toml, hence make sure backup this file, or modify your .gitignore locally.

Testing the chat API

To test the WebSocket API, you can use wscat, an open-source command line tool.

  1. Install NPM.
  2. Install wscat:
$ npm install -g wscat
  1. On the console, connect to your published API endpoint by executing the following command:
$ wscat -c wss://{YOUR-API-ID}.execute-api.{YOUR-REGION}{STAGE}
  1. To test the sendMessage function, send a JSON message like the following example. The Lambda function sends it back using the callback URL:
$ wscat -c wss://{YOUR-API-ID}.execute-api.{YOUR-REGION}
connected (press CTRL+C to quit)
> {"action":"sendmessage", "data":"hello world"}
< hello world

License Summary

This sample code is made available under a modified MIT license. See the LICENSE file.


This SAM application provides the Lambda functions, DynamoDB table, and roles to allow you to build a simple chat application based on API Gateway's new WebSocket-based API feature.




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