📚 Books Service API

The Books Service API is a core backend microservice within the eBooks Application, built with NestJS and deeply integrated into AWS Cloud Infrastructure.
It manages all book-related operations — from catalog management to user borrowing, returning, and analytics — while maintaining security, scalability, and seamless communication between microservices.

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🚀 Overview

This service powers the library and catalog domain of the eBooks ecosystem.
Every request from users passes securely through the AWS API Gateway, which validates Cognito-issued JWT tokens before routing traffic to backend microservices such as Books, Auth, and others.

This architecture ensures a fully managed, cloud-native, and secure workflow — combining serverless authentication, dynamic scaling, and real-time monitoring.

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🔐 Authentication Flow

All user requests are authenticated using AWS Cognito and validated through API Gateway Authorizers before reaching this service.

User → AWS Cognito (login/signup) → Token (JWT)
     ↓
AWS API Gateway (Authorizer + Routing)
     ↓
Books Service (NestJS + DynamoDB + S3)

🧭 The Books Service API itself doesn’t handle authentication logic. It trusts the identity verified by Cognito via API Gateway.

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✨ Core Features

• Librarian Operations

  • Create, update, delete, and fetch books.
  • Upload and manage book covers with AWS S3.
  • Manage catalog data stored in DynamoDB.

• User Operations

  • Borrow and return books.
  • Token validation and authorization through API Gateway and Cognito.

• Statistics & Insights

  • Generate data insights on book borrowing and user engagement.

• Scalability & Monitoring

  • Built for performance using DynamoDB and CloudWatch for observability.

• Microservice Architecture

  • Fully managed through AWS API Gateway, secured with IAM roles.

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🧩 AWS Services Overview

AWS Service	Purpose
Cognito	Handles authentication and user identity (JWT issuance).
API Gateway	Entry point for all client requests; validates Cognito tokens and routes to microservices.
DynamoDB	Stores all book and borrowing data with scalable performance.
S3	Stores and retrieves book cover images and media files.
CloudWatch	Collects logs, tracks metrics, and monitors API performance.
CloudFront	Distributes static assets for frontend and improves latency.
IAM	Manages permissions between AWS services and microservices.

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🧠 Architecture Overview

src/
├── app.module.ts              # Root module configuration
├── books/                     # Books domain logic
│   ├── dto/                   # DTOs for book operations
│   ├── entities/              # Book schema definitions
│   ├── books.controller.ts    # REST endpoints
│   ├── books.service.ts       # Core business logic
│   ├── books.repository.ts    # DynamoDB data layer
│   └── books.module.ts        # Module setup
├── config/
│   ├── dynamodb.config.ts     # DynamoDB client setup
│   ├── s3.config.ts           # S3 configuration
├── services/
│   ├── s3.service.ts          # File handling & uploads
│   ├── app.controller.ts
│   └── app.service.ts
├── main.ts                    # Application entry point
└── test/                      # Jest tests

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⚙️ Setup & Installation

Prerequisites

• Node.js v18+
• NestJS CLI (npm i -g @nestjs/cli)
• AWS account with configured credentials
• DynamoDB Table and S3 Bucket created

Installation

git clone https://github.com/Zaiidmo/eBooks-API.git
cd eBooks-API
npm install
cp .env.example .env

Configure environment variables:

cp .env.example .env

Update the newly created .env file with proper variables

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🧪 Running & Testing

Development

npm run start:dev

Production

npm run build
npm run start:prod

Testing

npm test
npm run test:cov

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🔌 API Endpoints

Librarian Routes

Method	Endpoint	Description
POST	/books	Add a new book
PUT	/books/:id	Update book details
DELETE	/books/:id	Delete a book
GET	/books	List all books
GET	/books/:id	Get book details

User Routes

Method	Endpoint	Description
POST	/books/:id/borrow	Borrow a book
POST	/books/:id/return	Return a book

Statistics

Method	Endpoint	Description
GET	/books/statistics	Retrieve usage metrics

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🧱 CI/CD Pipeline (Jenkins)

Stages:

1. Build: npm ci && npm run build
2. Test: Executes automated test suite
3. Dockerize: Builds and tags Docker image
4. Deploy: Pushes to EC2 or ECR via Jenkins agents
5. Monitor: Tracks metrics via AWS CloudWatch

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🧰 Tech Stack

Layer	Technology
Language	TypeScript
Framework	NestJS
Database	AWS DynamoDB
Storage	AWS S3
Auth Flow	Cognito + API Gateway Authorizer
Monitoring	AWS CloudWatch
Delivery	AWS CloudFront
CI/CD	Jenkins + Docker + EC2

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🌐 Related Repository

The corresponding Frontend Application (handling Cognito authentication and user interaction) is available here:
👉 eBooks Frontend

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🧑‍💻 Contributing

Contributions are welcome!
To propose an improvement or fix, please open a pull request or issue.
📧 Contact: [email protected]

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🪪 License

Licensed under the MIT License.
© 2025 — Crafted by TheVlpha. You’ll know when you see it.