Rung 7 — The Production URL Shortener Service¶

Target month: Shipped by end of M11 = end of May 2027 (started in M10) Calendar deadline: May 31, 2027 Phase alignment: Phase 07 — Enterprise Spring & Data Signal level: Full-stack Spring → proves you can ship a service, not just a class

What It Is¶

A fully-functional URL shortener, built with Spring Boot 3.x + Java 21, deployed to a real, publicly-reachable URL, with observability, tests, CI/CD, and documentation that meet a production bar.

The URL shortener is chosen deliberately: it is the classic system-design study problem, so shipping a real one is directly study-relevant. It has just enough moving pieces (persistence, caching, rate limiting, redirects, analytics) to demand a real architecture without ballooning in scope.

Feature scope (freeze this list; do not expand)¶

POST /api/v1/shorten — accepts a long URL, returns a short code (7 chars, base62)
GET /{code} — 302-redirect to the long URL
GET /api/v1/stats/{code} — returns hit count, first-hit, last-hit timestamps
DELETE /api/v1/links/{code} — auth-required, removes a link
Auth: minimal API-key auth on write endpoints (POST, DELETE). API key stored hashed.
Rate limiting: IP-based on POST, using the Rung 5 rate limiter. This is the payoff of Rung 5.
Persistence: PostgreSQL via Spring Data JPA (managed schema via Flyway)
Caching: Redis for hot short-code lookups (write-through cache on redirect)
Observability: Micrometer metrics, /actuator/health, /actuator/metrics behind auth, structured JSON logs
Docs: OpenAPI 3 spec auto-generated via springdoc, hosted at /swagger-ui

Deployment¶

Deploy to a real host that the public internet can hit. Options in order of preference:

Fly.io — free tier still workable for a small JVM app; global anycast is nice for a URL shortener
Railway — slightly more expensive but simpler; good Postgres+Redis integration
Render — free web service tier with limitations; acceptable
AWS EC2 t3.small + RDS + ElastiCache — expensive, but the strongest resume signal because it’s what enterprises use
Zoho Catalyst / AppSail — dogfooding-friendly if you’re a Zoho employee; strong signal in-house

The deployed URL goes in the repo README and on your portfolio landing page as a live “try it now” link.

Where To Publish¶

Repo: github.com/RaghulR2003/shortlnk (or a name you like) — public, pinned
Live URL: e.g., shortlnk.raghulr2003.dev or shortlnk.fly.dev, linked from the repo README hero section
API docs: <live-url>/swagger-ui.html — accessible without auth for the docs themselves
Blog: Hashnode. Title: “Building a production URL shortener in Spring Boot 3 + Java 21 — what I skipped, what I couldn’t skip, and why.” Focus on decisions and tradeoffs, not tutorials.
LinkedIn: Long-form. Include the live URL. This is the first rung where a recruiter can literally play with your work.
Portfolio landing: “Try it now” tile with a live short-URL form embedded

Signal It Sends¶

You can ship a service. Not a class. Not a library. A service that a stranger can hit from a browser. This is the difference the M13 pitch hinges on.
You know Spring Boot 3. Not “Spring MVC from a 2018 tutorial.” Modern Spring, with modern Java. This is directly the stack most Indian MNC Java job postings ask for.
You use real infra. Postgres, Redis, Testcontainers, Docker, a real host. Every one of these is a resume-parseable keyword.
You wire the rungs together. The rate limiter is Rung 5’s output. This rung consumes your own libraries. Nothing signals seniority faster than a portfolio where the rungs feed each other.
You care about observability. Micrometer, structured logs, health endpoints. This is what separates a hobby project from a service that’s ready to be operated.
You write about tradeoffs. The blog post is not a tutorial. It is a decisions post. Decisions posts are what senior engineers actually read.

Common Failure Modes¶

Scope explosion. “I’ll add QR codes and custom aliases and OAuth and expiring URLs.” Every one of these turns a 4-week rung into a 12-week rung. Freeze the feature list on day 1.
Local-only demos. “It works on my machine.” If it isn’t deployed to a public URL, this rung has not been completed. The live URL is the whole point.
Skipping the analytics. Just returning a short URL isn’t enough; the analytics endpoint is what makes it a service rather than a toy.
Mocked persistence. Using H2 or an in-memory Map instead of real Postgres. This kills the resume-signal. Use Postgres from day 1, with Testcontainers for tests.
No architecture doc. Just having the code isn’t enough. ARCHITECTURE.md is what senior engineers read before looking at the code.
Free-tier expiry. Fly.io and Render will scale-to-zero or expire free tier services. Set a calendar reminder for M13 to verify the live URL is still up during job studies.
Not using the Rung 5 rate limiter. Just calling bucket4j or another library defeats the whole point of the rungs feeding each other. Use your own.

Time Estimate¶

Domain model + REST endpoints: ~10 hours
Spring Data JPA + Postgres + Flyway migrations: ~8 hours
Redis caching layer: ~5 hours
API-key auth + rate limiting integration: ~6 hours
Analytics endpoints + hit tracking: ~5 hours
OpenAPI + Swagger UI setup: ~2 hours
Micrometer + structured logging + actuator: ~4 hours
Unit + integration tests (Testcontainers): ~12 hours
Load test with k6: ~4 hours
Docker multi-stage image + deploy scripts: ~5 hours
CI/CD pipeline: ~4 hours
Deployment + DNS + TLS + host-specific config: ~5 hours
README, ARCHITECTURE.md, diagrams: ~5 hours
Blog post: ~10 hours
Total: ~85 hours over 8 weeks (~10-11 hours/week)

This is your all-of-M10-and-M11 rung. If you have not touched Spring by end of M10, you are behind.

Prerequisites¶

Rung 5 shipped (the rate limiter this depends on)
All files in 07_enterprise_spring_data/ read and worked through
Docker installed and working; you’ve built and run at least one image
One prior Spring Boot “tutorial” project completed as scaffolding practice (this can be done inside 07_enterprise_spring_data/projects/)
Basic Postgres + Redis knowledge (schema design, indexing, TTL, eviction policies)
Account and credit card on your chosen host (Fly.io, Railway, etc.) even if you stay in free tier — verify before M10 to avoid surprises

Stretch Goals (Optional)¶

Custom domain with TLS. s.raghulr2003.dev or similar. This adds a real DNS + TLS story to your resume. Cloudflare + Let’s Encrypt is the free path.
Grafana + Prometheus dashboard. Scrape Micrometer metrics into Prometheus, view in a hosted Grafana. Screenshot in the README. Direct signal to any SRE-adjacent recruiter.
Chaos test. Kill the Redis container mid-load-test, show that the service continues to serve (from Postgres) but with degraded latency. This is the exact scenario an study partner will ask about.
Multi-region deployment on Fly.io. Fly makes this near-trivial. Adds a distributed-systems story that would otherwise wait for Rung 8.

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Rung 7 — The Production URL Shortener Service¶

What It Is¶

Feature scope (freeze this list; do not expand)¶

Deployment¶

Where To Publish¶

Acceptance Criteria¶

Functional¶

Quality¶

Deployment¶

Documentation¶

Signal It Sends¶

Common Failure Modes¶

Time Estimate¶

Prerequisites¶

Stretch Goals (Optional)¶