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Architecture and Folder Structure

Last Updated: June 29, 2025

This document explains the technology stack, architectural principles, main folder structure, and execution methods of the comfy-surfai-backend repository.

1. Tech Stack​

  • Framework: NestJS (@nestjs/core)
  • Database: PostgreSQL
  • ORM: TypeORM (@nestjs/typeorm, typeorm, pg)
  • Authentication:
    • Strategy: Passport.js (@nestjs/passport, passport)
    • JWT: JSON Web Token (@nestjs/jwt, passport-jwt)
    • Google OAuth 2.0: passport-google-oauth20
    • Local (Email/Password): passport-local
  • Real-time Communication: WebSocket (@nestjs/platform-ws, ws)
  • Security:
    • Password Hashing: bcrypt
    • CSRF Defense: csurf
    • Cookie Parsing: cookie-parser
  • Validation: class-validator, class-transformer
  • API Documentation: Swagger (@nestjs/swagger)

2. Architectural Principles​

The backend follows a module-based Layered Architecture.

  • Modularity: Composed of independent modules like AuthModule, WorkflowModule, etc., to clearly separate responsibilities by function. Each module has its own Controller, Service, and Provider.
  • Layer Separation:
    • Controller: Only receives HTTP requests, validates them, and calls appropriate service methods. Does not contain business logic.
    • Service: Handles core business logic. Actual operations such as communicating with the database or calling other services occur here.
    • Repository/Entity: Abstracts interaction with the database. TypeORM handles this role.
  • Dependency Injection (DI): All dependencies are managed through constructor injection, reducing coupling between components and improving testability.

3. Main Folder Structure​

/src
├── 📁 admin/              # Admin-specific feature modules
│   └── 📁 workflow/
├── 📁 auth/               # Authentication/Authorization (login, guards, strategies) related modules
│   ├── 📁 guards/
│   └── 📁 strategies/
├── 📁 comfyui/            # Module responsible for communication with ComfyUI compute server
├── 📁 langchain/           # Module responsible for communication with LangChain server
├── 📁 common/             # Elements commonly used across multiple modules
│   ├── 📁 decorators/
│   ├── 📁 dto/            # Data Transfer Objects
│   ├── 📁 entities/       # TypeORM entities mapped to database tables
│   ├── 📁 enums/
│   ├── 📁 events/         # WebSocket Gateway
│   └── 📁 interfaces/     # Interfaces for type definitions
├── 📁 generated-output/   # Module for managing generated results (history)
├── 📁 storage/            # Module for integrating with file storage (Cloudflare R2)
├── 📁 workflow/           # Module for managing workflow templates
│
└── 📄 main.ts             # Application entry point (middleware, pipes, etc. configuration)

4. How to Run and Test​

Running in Development Environment​

  1. Install and run PostgreSQL database locally.
  2. Create a .env.development file in the project root and configure necessary environment variables (DB info, JWT secrets, etc.).
  3. Install all dependencies with npm install.
  4. Run the development server with npm run start:dev. The server will run on http://localhost:3000.

Running Unit/Integration Tests​

  • Run all tests written in the project. 
    npm test

5. Key Environment Variables​

The following variables are required in the .env file or production environment to run the application.

  • NODE_ENV: development or production
  • PORT: Server port (default: 3000)
  • Database: DB_HOST, DB_PORT, DB_USERNAME, DB_PASSWORD, DB_DATABASE or DATABASE_URL
  • Authentication: JWT_SECRET, JWT_REFRESH_SECRET, JWT_REFRESH_EXPIRATION_TIME
  • Google OAuth: GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET
  • Service URLs: API_BASE_URL (backend's own address), FRONTEND_URL (frontend address), ROOT_DOMAIN (common domain for production)
  • Compute Server: COMFYUI_HOST, NGINX_USERNAME, NGINX_PASSWORD
  • File Storage: R2_ACCOUNT_ID, R2_BUCKET_NAME, R2_ACCESS_KEY_ID, R2_SECRET_ACCESS_KEY
  • Admin: ADMIN_EMAILS