https://github.com/sharjeelsafdar/project14c-virtual-lolly-app-event-driven

A serverless JAMstack Virtual Lolly App with event-driven architecture using Gatsby, TypeScript, AppSync, DynamoDB, Lambda, StepFunctions, EventBridge, CloudFront, and Lambda@Edge.
https://github.com/sharjeelsafdar/project14c-virtual-lolly-app-event-driven

amplify appsync aws aws-cdk cloudfront dynamodb event-driven eventbridge gatsbyjs jamstack lambda-edge lambda-functions s3 serverless stepfunctions typescript

Last synced: 23 days ago
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A serverless JAMstack Virtual Lolly App with event-driven architecture using Gatsby, TypeScript, AppSync, DynamoDB, Lambda, StepFunctions, EventBridge, CloudFront, and Lambda@Edge.

• Host: GitHub
• URL: https://github.com/sharjeelsafdar/project14c-virtual-lolly-app-event-driven
• Owner: SharjeelSafdar
• Created: 2021-06-30T01:50:19.000Z (almost 4 years ago)
• Default Branch: main
• Last Pushed: 2021-08-13T11:09:11.000Z (over 3 years ago)
• Last Synced: 2025-02-09T07:43:08.035Z (3 months ago)
• Topics: amplify, appsync, aws, aws-cdk, cloudfront, dynamodb, event-driven, eventbridge, gatsbyjs, jamstack, lambda-edge, lambda-functions, s3, serverless, stepfunctions, typescript
• Language: TypeScript
• Homepage: https://dfloplqh4uaf7.cloudfront.net/
• Size: 633 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        


  

    

  





  Project 14C: Serverless JAMstack Virtual Lolly App with Event-Driven Architecture



## Link to Web App

A serverless JAMstack Virtual Lolly App with Gatsby, TypeScript, AppSync, DynamoDB, Lambda, StepFunctions, EventBridge, CloudFront, and Lambda@Edge. The web app has been deployed to AWS CloudFront, and can be accessed [here](https://dfloplqh4uaf7.cloudfront.net).

## Features

The following are some of the features of this project:

- A form for creating a new Lolly at `/create-new` using [Formik](https://formik.org/docs/overview) and [Yup](https://github.com/jquense/yup)

- Uses [DynamoDB](https://aws.amazon.com/dynamodb/) table to store the information about all the lollipops

- A GraphQL API with [AWS AppSync](https://aws.amazon.com/appsync/) to interact with DynamoDB

- All lollies are fetched, and static pages are built for each one at build time.

- A [Lambda@Edge Function](https://aws.amazon.com/lambda/edge/) works as an SSR fallback: all lollies not having a static page are redirected to this function.

- Demonstrates CRUD operations using DynamoDB through the GraphQL API

- The AppSync queries are performed synchronously with a DynamoDB data source.

- The AppSync mutation `createLolly` is performed assynchronously. An HTTP data source simply puts the information about the mutation on [EventBridge](https://aws.amazon.com/eventbridge/) default bus.

- EventBridge invokes a [AWS Step Functions](https://aws.amazon.com/step-functions/) State Machine which orchestrates four [Lambda](https://aws.amazon.com/lambda/) functions in a sequence.

- First Lambda function, `ddbLambda` performs the actual mutation on the DynamoDB Table with the help of `aws-sdk`.

- Second Lambda function, `gqlLambda` calls a mutation on AppSync called `lollyCreated`.

- The client listens for this mutation with an AppSync subscription called `onLollyCreated` and redirects to the new lolly page.

- The third Lambda function, `snsLambda` publishes a message about the new lolly on an [SNS](https://aws.amazon.com/sns/) topic to notify through email.

- The last Lambda function sends a post request on GitHub api to trigger a workflow to redeploy the Gatsby site to S3.

- Uses [Amplify](https://amplify.com/) for GraphQL queries and mutations at client side

- Bootstrapped with [GatsbyJS](https://www.gatsbyjs.com/)

- Additionally, includes TypeScript support for gatsby-config, gatsby-node, gatsby-browser and gatsby-ssr files

- Site hosted on [AWS CloudFront](https://aws.amazon.com/cloudfront/)

- CI/CD with [GitHub Actions](https://docs.github.com/en/actions)

- Completely typed with [TypeScript](https://www.typescriptlang.org/)

- Completely interactive and responsive design with vanilla CSS.

## Backend

This AWS CDK App deploys the backend infrastructure for Project 14C. The app consists of two stacks.

### Stack 1: AppSync GraphQL API and DynamoDB Table

It contanis the AWS services used by the web client. It has the following constructs:

- A DynamoDB Table to contain the lollies saved by the users

- An AppSync GraphQL API to access the lollies in the Table

- A Lamba function to perform the actual mutation on the DynamoDB table

- Another Lambda function to call an AppSync mutation to inform the client side about the new lolly through an AppSync subscription

- Another Lamba function to publish a message on SNS

- Another Lambda function sends post request to GitHub api to trigger the workflow to rebuild and redeploy the Gatsby app.

- A Step Functions State Machine to run these Lambda functions sequentially.

- An EventBridge rule to invoke this state machine when the `createLolly` mutation is performed by the client side



  



### Stack 2: CloudFront Distribution, S3 Bucket and Lambda Edge

It contains the infrastructure to deploy frontend client. It has the following constructs:

- A [S3](https://aws.amazon.com/s3/) Bucket with public access to store the static assets of Gatsby web app

- A Cloud Front Distribution to serve the static assets through a CDN

- A Lambda@Edge function triggered at `origin_response` event that tries to build and serve a static page for a lolly for which there is no static page in the S3 bucket yet. Otherwise, it redirects to `/404` page