AWS Microservices(Modular) Deployment

Summary

Production-style deployment of backend microservices on AWS with automated CI/CD.

Architecture

• CloudFront (/ → S3, /api/* → ALB)
• VPC with public and private subnets
• ALB in public subnets (multi-AZ)
• EC2 in private subnet
• NAT for outbound access only

Services

• Order Service (FastAPI)
• Payment Service (FastAPI)
• systemd-managed processes

CI/CD

• GitHub Actions
• OIDC-based authentication
• Deployment via AWS SSM

CI/CD Flow
──────────────────
Developer
   ↓
GitHub (Private)
   ↓
GitHub Actions (OIDC)
   ↓
AWS Account
 ├─ EC2 (backend deploy)
 └─ S3 (frontend deploy)

Frontend:
---------

    - Code is pushed to release branch
    - Workflow builds the dist folder
    - Files in dist folder pushed to S3

Backend - Microservices
-----------------------
    - GitHub Actions triggers deployment via AWS SSM
    - Code is fetched on the instance during deployment
    - Services restarted using systemd
    - Services run as systemd-managed units

Networking

• Single VPC spanning multiple Availability Zones
• Application Load Balancer deployed in public subnets (ap-south-1b, ap-south-1c)
• Backend EC2 instances run in a private subnet (ap-south-1a)
• ALB is the only ingress point for API traffic
• EC2 instances have no direct internet access
• Outbound traffic from EC2 is routed through a NAT Gateway
• Internet Gateway attached to the VPC for public subnet access

Logging

• CloudWatch Agent
• systemd / journalctl logs
• Structured JSON format
• Request ID tracking

Repositories

(Source code is private)

• order-microservice
• payment-service
• gateway-infra
• gateway-fe

Future Enhancements

• Docker-based deployment - In progress
• Terraform for infrastructure provisioning