Products & Reviews management

Set of services for managing products and their reviews.

Automatically calculates average rating for each product and updates it when review is created/edited/deleted.

Technology stack

• NestJS framework
• TypeORM ORM for database operations
• MySQL DB engine
• RabbitMQ message broker
• Redis in-memory data structure store used for caching
• Docker for containerization
• docker-compose for running multi-container Docker applications

Services

product-reviews

Contains modules for managing products and their reviews. Runs on localhost:3000.

Swagger API is available on localhost:3000/api.

• Products module
  • provides REST API for managing products
• Reviews module
  • provides REST API for managing reviews
• App module
  • provides HTML page on root path with all products and their reviews

review-processor

Contains module for updating average product ratings based on reviews.

Architecture

• product-reviews:
  • handling all DB operations related to products and reviews
  • using Redis for caching products and reviews to decrease DB traffic
  • sending messages to dedicated queue in RabbitMQ about rating recalculation needs
• review-processor:
  • listening for messages on dedicated RabbitMQ queue
  • fetching product reviews from DB to recalculate average product rating
  • stores new rating into DB
  • invalidates relevant caches in Redis
  • can be scaled to n replicas as needed
• dynamic configuration based on .env file

Installation

$ npm install

Running the app on localhost

# start dependencies
$ docker-compose up -d db rabbitmq redis

# start product-reviews service
$ npm run start:product-reviews

# start review-processor service
$ npm run start:review-processor

# or start both just by running
$ npm run start

# watch mode
$ npm run start:dev

# production mode
$ npm run start:prod:<service-name>

Running the app in docker

# build & run unit tests & start all services (review-processor in 2 instances - no limit on number of instances)
$ docker-compose up --build -d

Testing

# unit tests
$ npm run test

# e2e tests
$ npm run test:e2e

# test coverage
$ npm run test:cov

# lint
$ npm run lint

# formatting
$ npm run format

Documentation

Generated from codebase using compodoc.

$ npm run compodoc

Optional TODOs

• extract entities to library to remove redundant definitions per app
• health check endpoints to be used in k8s

Known issues (to be resolved)

• e2e tests doesn't end properly, they pass but something is wrong with teardown