Link Shortener

A Spring Boot service that turns long URLs into short codes. Users can register, log in (JWT), create/manage links, and anyone can be redirected by short code.

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Requirements

• Docker (Desktop/Engine) with Compose v2
• Git
• (Optional) JDK 21 for local IDE runs

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Environment

A sample file .env.example is included. Create your local env once:

cp .env.example .env

• For IDE/local runs, .env defaults to SPRING_PROFILES_ACTIVE=dev (H2).
• In Docker, docker-compose sets SPRING_PROFILES_ACTIVE=prod and injects Postgres settings for the app container.
• Keep real secrets (e.g., JWT_SECRET) only in your local .env.

Variables used by the app

• SPRING_PROFILES_ACTIVE — dev (H2) or prod (PostgreSQL)
• dev / H2: DB_URL, DB_DRIVER, DB_USERNAME, DB_PASSWORD
• prod / PostgreSQL: DB_HOST, DB_PORT, DB_NAME, DB_USERNAME_PROD, DB_PASSWORD_PROD
• Optional overrides (take precedence if set): SPRING_DATASOURCE_URL, SPRING_DATASOURCE_USERNAME, SPRING_DATASOURCE_PASSWORD

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Run with Docker (app + its own PostgreSQL)

Build and start both containers:

docker compose up --build

What you get:

• app on http://localhost:8080 (profile prod)
• db: postgres:16-alpine with database url_shortener, user url_user, password url_pass
• Persistent volume pgdata
• Flyway runs migrations for PostgreSQL on startup

Useful:

# Stop containers (keep volume)
docker compose down

# Reset database (remove volume)
docker compose down -v

# psql into DB
docker exec -it linkshortener-db psql -U url_user -d url_shortener

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Run in IDE (dev profile, H2)

./gradlew bootRun
# Windows:
# gradlew.bat bootRun

• H2 console: http://localhost:8080/h2-console
• Swagger UI: http://localhost:8080/swagger-ui
  Use the selector to switch between api-v1 and public docs.

OpenAPI JSON:

• /v3/api-docs/api-v1
• /v3/api-docs/public

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API Endpoints

Authentication (api-v1)

Method	Path	Description
POST	/api/v1/auth/register	Register a new user
POST	/api/v1/auth/login	Log in and get JWT tokens
POST	/api/v1/auth/refresh	Refresh access token
POST	/api/v1/auth/logout	Logout and revoke token

Links (api-v1, requires JWT)

Method	Path	Description
POST	/api/v1/links	Create a short link
GET	/api/v1/links/my_all_links	List all your links
GET	/api/v1/links/my_all_active_links	List only active links
DELETE	/api/v1/links/delete/{id}	Delete link by id

Cache (api-v1)

Method	Path	Description
GET	/api/v1/cache	Cache info

Public

Method	Path	Description
GET	/health	Health check
GET	/api/links/{code}	Redirect by short code

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Deployment

The project is automatically deployed to a remote server via GitHub Actions.
Every merge/push to the master branch triggers the workflow (.github/workflows/deploy.yml) which:

1. Connects to the server (user@ip via SSH)
2. Executes the deploy.sh script
3. Updates the repository (git pull origin master)
4. Rebuilds Docker containers and restarts the application (docker compose up -d --build)

Note: Private keys for GitHub Actions are stored in GitHub Secrets and are not published in the README.

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Postman Collections

There are two collections in the postman/ folder:

• Linkshortener_local_postman_collection.json – for local version (http://localhost:8080)
• Linkshortener_deployed_postman_collection.json – for the production server (http://91.225.7.129:8080)

To use the collections, import them into Postman.

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Swagger (Production)

API documentation for the production server is available here:
Go to Swagger

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What this app can do

• Shorten any valid URL and redirect by short code
• Manage your own links (create, list, delete, see active ones)
• JWT-based authentication and token refresh
• Database migrations via Flyway (H2 for dev, PostgreSQL for prod)
• Dockerized local setup (app + DB)

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Build (fat JAR)

./gradlew clean bootJar -x checkstyleMain -x checkstyleTest

Output: build/libs/*.jar

Runtime images:

• Builder: gradle:8.14.3-jdk21
• Runtime: eclipse-temurin:21-jre