kra-lambdas

Serverless background workers for the KRA portfolio. These functions handle asynchronous tasks such as image processing and automated notifications, triggered by AWS S3 events and DynamoDB Streams.

Stack: Node.js 20, TypeScript, AWS SDK v3 (SES, S3), Sharp for image manipulation, Esbuild for bundling, Vitest for unit testing.

Prerequisites

Node.js 20+ and Yarn
AWS CLI configured for testing or deployment
Amazon SES identity verified (for email notifications)

Quick Start

Install dependencies: yarn install
Run tests to verify logic: yarn test
Build the deployment bundles: yarn build
Bundles are generated in the dist/ directory.

Commands

Action	Command
Install dependencies	`yarn install`
Build bundles (Esbuild)	`yarn build`
Type checking	`yarn typecheck`
Unit tests (Vitest)	`yarn test`
Unit tests (Watch mode)	`yarn test:watch`

Functions

These functions are deployed as individual Lambdas and triggered by AWS events.

Handler	Trigger	Description
`src/index.handler`	S3 (Object Created)	Thumbnail Generator: Detects uploads to `images/` and generates WebP thumbnails in `thumbnails/`.
`src/email-handler.handler`	DynamoDB Stream (INSERT)	Email Notifier: Processes new items in the `leads` table and sends a notification email via SES.

Architecture

flowchart TD
  subgraph AWS_Events [Events]
    S3["S3: images/*"]
    DDB["DynamoDB Stream: leads"]
  end

  subgraph kra_lambdas [kra-lambdas]
    THUMB[Thumbnail Gen]
    EMAIL[Email Handler]
  end

  subgraph Services [AWS Services]
    SES[Amazon SES]
    S3_STORE["S3: thumbnails/*"]
  end

  S3 -->|Trigger| THUMB
  THUMB -->|Write| S3_STORE
  DDB -->|Trigger| EMAIL
  EMAIL -->|Send| SES

Full system architecture (C4 Level 1, 2 & 3): kra-docs-architecture

Workflow: The handlers are designed to be idempotent and stateless. The thumbnail generator uses sharp for high-performance image processing, while the email handler consumes the NewImage from DynamoDB streams to capture lead data.

Source layout

kra-lambdas/
├── esbuild.config.mjs    # Build configuration
├── package.json
├── src/
│   ├── index.ts          # S3 thumbnail handler
│   ├── email-handler.ts  # DynamoDB stream handler
│   ├── thumbnail.ts      # Image processing logic
│   ├── email.ts          # SES notification logic
│   └── *.test.ts         # Vitest unit tests
└── dist/                 # Compiled assets (ignored)

Configuration

Environment variables configured in the Lambda environment (managed via Terraform in kra-infra):

Variable	Purpose
`FROM_EMAIL`	Verified SES email address used as sender and recipient
`AWS_REGION`	AWS region for SDK clients

Deployment

These functions are provisioned and managed via Terraform in the kra-infra repository. The CI/CD pipeline in GitHub Actions automatically builds and uploads the zip files to the corresponding Lambda functions on every push to main.

krealalejo/kra-lambdas