Container Engineering: Multi-Service Apps to AWS — Demo Repo

Demo code for the JunctionX Kathmandu talk. A simple multi-service app (React frontend + Express API + Postgres) used to teach Docker, Docker Compose, and deployment to AWS App Runner.

What's inside

.
├── frontend/            React (Vite) app — lists rides from the API
├── api/                 Express API + Postgres (pg)
├── frontend-watch/      Tiny app for the `docker compose watch` demo
├── compose.yaml         Full stack: healthchecks, networks, named volume
├── compose.broken.yaml  Race-condition version (no healthcheck) for Section 5a
├── compose.watch.yaml   Live-reload demo for Section 6
├── demos/               Step-by-step scripts, one per section
├── aws/                 ECR + App Runner setup + deploy scripts
└── CHEATSHEET.md        Every command in one place

Ports

Service	URL
frontend	http://localhost:3000
api	http://localhost:4000
api rides	http://localhost:4000/rides
frontend-watch	http://localhost:3001
postgres	localhost:5432

Quick start

docker compose up
# open http://localhost:3000

Run the demos (one per talk section)

demos/01-docker-basics.sh   # Section 2  — build + run one container
demos/02-pain-demo.sh       # Section 3  — broken docker run, then fixed with a network
demos/03-compose.sh         # Section 4  — one file, one command
demos/04-healthcheck.sh     # Section 5a — race condition vs healthcheck
demos/05-volumes.sh         # Section 5c — data persistence
demos/06-watch.sh           # Section 6  — live reload

Run the blocks one at a time on stage (especially the pain demo) — don't execute the whole script at once; some steps fail on purpose.

AWS (App Runner)

See aws/setup.md. Do the one-time setup before the talk; the on-stage step is just ./aws/03-deploy.sh.

Notes

• The frontend fetches the API at http://localhost:4000 because the browser runs on your host, not inside the Docker network. Container-to-container, you'd use the service name (http://api:4000) — that's the service-discovery point in Section 4.
• The API serves / and /health even without a database, so it stays healthy on App Runner. /rides needs Postgres.