Fibonacci sequence... with AWS CDK!

Overview

This is a proof-of-concept project that demonstrates IaC AWS resource deployment using TypeScript development with CDK. The goals of this project are:

• Building a Pipeline using AWS CDK for application architectures defined using CDK
• Building a Pipeline to be used with multiple projects (easily added or removed)
• Deploying products composed of multiple deployable elements

All of the above resources will be launched and configured as a stack using the Cloudformation template created by CDK Toolkit. The cdk.json file tells the CDK Toolkit how to execute your app.

Prerequisites

• S3 Bucket with a names.txt file, a list of words to be used as Sequence Label values; words are not repeated; they have no other meaning
• DynamoDB table with columns 'sequence_labels' and 'fib_values' must be created beforehand and configured in the .env file
• GitHub personal access token with the following scope: admin:repo_hook, repo, workflow
• Key for GitHub personal access token stored in AWS KMS

Application Architecture

Fibonacci Sequence Application

The following resources will be provisioned for the Fibonacci Sequence API created when running cdk deploy:

• Four Lambda functions:
  • Lambda A reads the File to find the last Sequence Label from the S3 and sends it onto Lambda B
  • Lambda B reads the last two Fibonacci Values entries from the DB and passes them, along with the new Sequence Label, onto Lambda C.
  • Lambda C adds the two numbers together and writes the new Fibonacci Value to the DB, labeling it with the Sequence Label
  • Lambda D lets you query the DB, returning the Fibonacci Value given for the Sequence Label, or returning the Sequence Label given for a given Fibonacci Value
• Step Function for running Lambda functions in order
• Cloudwatch Event for running Step Function once a day
• API Gateway that accepts POST requests for querying Fibonacci value associated with names and vice versa

CI/CD Pipeline

This API will be built and deployed using CodePipeline, also created with CDK, which will install npm packages, build this project, and synthesize the stack defined. A pre-prod environment will be set up for testing, and once successful, the application will be deployed in production. This process is triggered whenever changes are pushed to this repo's app-def folder.

Useful commands

• npm run build compile typescript to js
• npm run watch watch for changes and compile
• npm run test perform the jest unit tests
• 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