Full-stack pharmacy e-commerce migrated from microservices to a modular NestJS monolith
34 weeks
7
Production
Key Challenge
Consolidating 7 microservice auth flows into a single modular NestJS auth module with account-type routing
Skills Demonstrated
Migrated a pharmacy backend from microservices to a modular NestJS monolith with MySQL, covering auth, products, orders, prescriptions, notifications, and a Next.js storefront.
Microservices architecture created auth duplication and deployment overhead for a small team
Modular monolith with shared guards, interceptors, and unified auth module
Single deployable API with 10+ modules covering full pharmacy workflow
10+
Backend modules
3
Account types
10+
Backend modules
3
Account types
v1
API version
Order management
Successfully migrated pharmacy platform to a maintainable modular monolith.
Reduced deployment complexity from 7 services to 1 while preserving all features.
10+
Modules consolidated
34
Weeks migration
System architecture overview
Modular NestJS monolith with domain modules (auth, users, products, orders, prescriptions, pharmacy, location, upload, search, admin, notifications).
Shared common layer provides guards, interceptors, filters, pipes, and decorators. TypeORM entities map to MySQL with migrations.
Next.js frontend communicates via REST API with JWT + refresh token flow.
Infrastructure & Deployment
Backend on cloud VM or container with MySQL 8. AWS S3 for file uploads. Next.js frontend on AWS Amplify or Vercel.
Patient, pharmacy, and admin authentication with JWT refresh.
Searchable product listing with filters and categories.
Full order lifecycle from cart to fulfillment.
Upload and manage prescription documents.
Location-based search for nearby pharmacies.
Backend admin operations and analytics.
The Problem
Each microservice had its own JWT validation and user lookup logic.
How I Solved It
Single auth module with account-type strategies and shared JwtAuthGuard.
@Post('auth/:accountType/signin')
signin(@Param('accountType') type: AccountType, @Body() dto: SignInDto) {
return this.authService.signin(type, dto);
}The Problem
Prescription uploads needed secure storage with access control.
How I Solved It
AWS S3 upload module with signed URLs and pharmacy-only access guards.
const url = await this.s3Service.upload(file, `prescriptions/${userId}/`);
return { url, expiresIn: 3600 };The Problem
Users need to search products, pharmacies, and orders from one endpoint.
How I Solved It
Dedicated search module with typed query builders per entity type.
Monolith wins for small teams
Microservices overhead wasn't justified—modular monolith gave us boundaries without network complexity.
Account-type routing in auth
Patient, pharmacy, and admin signin paths share JWT infrastructure but differ in registration and profile schemas.
Migration needs contract tests
API contract tests against the old microservices caught breaking changes during consolidation.
What I'd Do Differently
Start with monolith architecture and add service extraction only when a module truly needs independent scaling.
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