WebSocketAPI Sample Chat

A simple WebSocket Chat example using AWS WebSocket API.

This is almost same with this article from AWS blog but this is written with Serverless framework instead of CloudFormation.

I think this is a good start to

test a new feature from the latest aws-sdk-js such as DeleteConnection API.
test reliability like latency between endpoints by the simplest example.

Prerequisites

NodeJS@10
yarn
AWS account
AWS credential with grants of CloudFormation, Lambda, ApiGateway, S3, CloudWatch and DynamoDB

Environment variables

Name	Value
NODE_ENV	`development` for `inline-source-map` or `production`.
AWS_REGION	A target of `aws region` to deploy this stack.
CONNECTION_TABLE_NAME	A DynamoDB table name to store connection ids, default is `ConnectionIds`.

Walkthrough

Please check any other settings in serverless.yml such as region before deploy this system on your AWS environment.

$ AWS_REGION=ap-northeast-2 yarn deploy
Serverless: Bundling with Webpack...
Time: 4989ms
Built at: 11/17/2019 8:42:21 AM
...
Serverless: Checking Stack update progress...
Serverless: Stack update finished...
Service Information
...
endpoints:
  wss://your-backend-endpoint-url/development
...

$ yarn wscat -c "wss://your-backend-endpoint-url"
Connected (press CTRL+C to quit)
> hello
< hello
> happy coding
< happy coding
> exit
Disconnected (code: 1000, reason: "Connection Closed Normally")

aws-sdk in AWS Lambda for JavaScript runtime doesn't have DeleteConnection API as default, so I use small polyfill for that. This example would disconnect from the server-side when a client sent exit message.

Test your package size

sls package will make a serverless bundle for deployment. If you do not have a sls in your global environment, use yarn build instead.

# Build with inline-source-map for debugging.
$ yarn build && stat .serverless/websocket-chat.zip
File: .serverless/websocket-chat.zip
Size: 43041       Blocks: 88         IO Block: 4096   regular file

# Build without source-map for reducing a package size.
$ NODE_ENV=production yarn build && stat .serverless/websocket-chat.zip
File: .serverless/websocket-chat.zip
Size: 1558        Blocks: 8          IO Block: 4096   regular file

Show your deployment information

sls info will show your stack information. Or, use yarn status instead.

# Show current deployment information with correct environment variables.
$ NODE_ENV=production AWS_REGION=ap-northeast-2 yarn status
Service Information
service: websocket-chat
stage: production
region: ap-northeast-2
stack: websocket-chat-production
resources: 25
...

# Error occurred when use show command without the region option.
$ yarn status
 Serverless Warning --------------------------------------

  A valid environment variable to satisfy the declaration 'env:AWS_REGION' could not be found.


  Serverless Error ---------------------------------------

  Stack with id websocket-chat-development does not exist
...

If you've obviously deployed it and can't find the information, make sure your environment variable is correct.

Print your serverless configuration

sls print will show your serverless.yml configuration. Or, use yarn print-config.

$ AWS_REGION=ap-northeast-2 yarn status
service:
  name: websocket-chat
plugins:
  - serverless-webpack
...

Delete stack

It is very important to delete this stack after your test is end. Our wallet is precious.

sls remove will do that, or use yarn delete-stack.

# Please be careful your environment variables to delete a stack.
$ AWS_REGION=ap-northeast-2 yarn delete-stack
Serverless: Getting all objects in S3 bucket...
Serverless: Removing objects in S3 bucket...
Serverless: Removing Stack...
Serverless: Checking Stack removal progress...
...............................................
Serverless: Stack removal finished...

Of course, if you want to delete a proper stack, you should use correct environment variables that use at deployment time such as NODE_ENV, AWS_REGION, CONNECTION_TABLE_NAME. Otherwise, you cannot delete a stack or will delete a wrong stack.

License

MIT

lacti / websocket-api-sample-chat Goto Github PK