Microservice Architecture and Singleton Design Pattern Experiment with ExpressJS, Sequelize, Google Books API, JWT

I wanted to experience Microservice infrastructure in Node.js, therefore I created this project.

Database per Microservice microservice design pattern has been used for both services.

Singleton pattern has been used in both microservices.

Table of Contents

1. Requirements
2. Overview
3. Configuration and Initialization
   • Environment Variables Configurations
   • API Gateway Configuration
   • Public and Private Keys
   • MySQL Configuration
   • Redis Configuration
4. Install & Run
5. API Documentation
6. TODO
7. Learn More & Resources
8. NOTE

Requirements 🔝

• Node.js 16.16.0+
• yarn 1.22.19 or npm 8.18.0 (the versions I used for installing/updating dependencies)
• ts-node (optional due to package.json files already include it but you may install globally)

Overview 🔝

The API consists two microservices that client-service and books-service.

client-service has built to authenticate users for adding books that have been fetching from book service to their bookmarks.

book-service has built to provide the books data for searching books on Google Books API and creating bookmarks.

Tech Stack: Google Books API, ExpressJS, JSON Web Token, Sequelize(Typescript), MySQL, Umzug, Winston(logger), Axios, Express-Gateway, Bcrypt | Argon2, ESlint & Prettier, axios-logger, Redis

Configuration and Initialization 🔝

API Gateway port is set to 8080 by default.

Environment Variables Configurations 🔝

There are .env.example files in both book-service and client-service.

Feel free to change their name as .env and set variables.

API Gateway Configuration 🔝

There are another configurations in gateway.config.yml

http:
  port: 8080 # api gateway port 
admin:
  port: 9876
  host: localhost
apiEndpoints: # api gateway configuration
  auth:
    host: localhost #auth service host in api gateway
    paths: '/auth/*' #auth service path in api gateway
  book:
    host: localhost #book service host in api gateway
    paths: '/books/*' #book service path in api gateway
serviceEndpoints: # both services configurations
  auth-service:
    url: 'http://localhost:8000/auth/' # auth service base uri
  book-service:
    url: 'http://localhost:8001/books/' # book service base uri
policies:
  - cors
  - log
  - proxy
pipelines:
  auth:
    apiEndpoints:
      - auth
    policies:
      - cors:
          - action:
              origin: false
      - proxy:
          - action:
              serviceEndpoint: auth-service 
              changeOrigin: true
              prependPath: false # for passing query strings and another nested paths
      - log:
        - action:
            message: ${req.method} ${req.originalUrl}
  book:
    apiEndpoints:
      - book
    policies:
      - cors:
          - action:
              origin: false
      - proxy:
          - action:
              serviceEndpoint: book-service 
              changeOrigin: true
              prependPath: false # for passing query strings and another nested paths
      - log:
        - action:
            message: ${req.method} ${req.originalUrl}

You can change this configuration. Here is the reference.

Public and Private Keys 🔝

You should provide private key named as private.pem and public key named as public.pem in root directories of services.

We read the keys in here and there.

You may use this RSA key generator. (RSA256) I had generated keys with 2048 bits key size to use.

MySQL Configuration 🔝

You should create your schemas for both of services in MySQL I said MySQL because I only tested MySQL not others. You may give it a try for other DBs.

e.g. I had created schemas as book_service and auth_service with utf8mb4 as charset and utf8mb4_unicode_ci as collation.

Redis Configuration 🔝

Redis has been used caching book searches for 30 minutes.

You must install the redis-server(Windows, wsl or linux).

Install & Run 🔝

Note: There are yarn.lock files in both services' folders. You'd better to use yarn.

---

You must go to both services and run command below to install dependencies:

cd book-service
yarn

#and

cd client-service
yarn

There are nodemon.json in services' folders. So you can run servers in development and watch mode:

cd book-service
yarn watch

#and

cd client-service
yarn watch

After do that for 2 services, you can run API gateway like below while 2 services run:

cd api-gateway
node server.js

API Documentation 🔝

You can take a glance at Postman API Docs.

TODO 🔝

• API Tests (Mocha & Chai || supertest || cypress)
• sh script to run 2 services with API Gateway || PM2
• Rearranging file and variable names and providing a TypeScript path resolver solution instead of relative paths.
• Discussion about monorepo (Lerna?) or polyrepo approaches on microservice architecture. If monorepo approach will be implemented, consider to discuss applying a bundler (webpack etc.).

Learn More & Resources 🔝

Will be added soon.

---

NOTE 🔝

If you're going to develop bigger project, please consider to use IoC design paradigm with SOLID principles for implementing Dependency Injection pattern due to Singleton pattern has been started to seem as Anti-pattern. (InversifyJS || TypeDI)