e04-mid-project — Microservices Checkout Platform

Purpose

University assignment implementing a polyglot microservices platform for e-commerce checkout and invoice payment. The system spans order placement, stock reservation, payment authorization, invoice issuance, and customer notification. Runs entirely via docker compose up --build — no host-level runtimes required.

Key Files

Subdirectories

For AI Agents

Working In This Directory

• Never hardcode secrets — all config goes in .env, referenced from docker-compose.yml
• Never run code directly on the host — all execution is inside Docker containers
• The single deploy command is docker compose up --build; do not suggest multi-step host setup
• Service-to-service calls use Docker Compose DNS names (e.g. http://payment:5002), never localhost
• Read .ai/AGENTS.md for the full universal agent instruction set before making changes

Testing Requirements

• make build — verify all images build successfully after any change
• Health check every service: GET /health must return {"status": "ok"}
• See scripts/gateway-smoke-test.sh for end-to-end smoke tests

Common Patterns

• Each service has its own Dockerfile, readme.md, and OpenAPI spec in docs/api-specs/
• Environment variables follow the pattern SERVICE_VAR_NAME=value in .env.example
• All write endpoints carry an Idempotency-Key header

Dependencies

External

• Docker + Docker Compose — container runtime
• Kong 3.x OSS — API Gateway (DB-less mode)
• Apache Kafka (KRaft) — event streaming
• PostgreSQL — one instance per service (five total)
• Brevo SMTP — transactional email relay (free tier)