🔗 URL Shortener

A production-ready, containerized URL shortening service built with Go, powered by PostgreSQL, Redis, and Kafka. Designed for performance, scalability, and observability.

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🛠️ Tech Stack

• Go — Backend logic
• PostgreSQL — Persistent URL store
• Redis — Caching layer
• Kafka — Visit logging and streaming
• Docker Compose — Service orchestration

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🚀 Features

• ✅ Shorten URLs with optional custom aliases
• ✅ Redirect from short URL to original
• ✅ Redis caching for fast lookups
• ✅ Kafka stream for visit logs (IP + timestamp)
• ✅ PostgreSQL auto-initialized via SQL script

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📦 Getting Started

1. Clone the repository and enter the directory

git clone https://github.com/your-username/url_shortener.git
cd url_shortener

2. Start the services

docker compose up --build

This starts:

• app (Go backend) at http://localhost:8080
• postgres on port 5433
• redis on port 6379
• kafka (with zookeeper) for logging events

📄 PostgreSQL is initialized using init.sql.

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📡 API Endpoints

🔹 POST /shorten

Create a shortened URL.

Request JSON:

{
  "url": "https://example.com",
  "customAlias": "ganesh"
}

Curl Example:

curl -X POST http://localhost:8080/shorten \
  -H "Content-Type: application/json" \
  -d '{"url": "https://example.com", "customAlias": "ganesh"}'

Response:

{
  "shortUrl": "http://localhost:8080/ganesh"
}

🔹 GET /{shortCode}

Redirect to the original URL.

Example:

curl -v http://localhost:8080/ganesh

Response:

HTTP/1.1 302 Found
Location: https://example.com

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🔁 Kafka Integration

Kafka is used to asynchronously log every URL visit.

🔸 Topic: url_visits

Each time a short URL is accessed (GET /{shortCode}), a message is published to the Kafka topic url_visits with the following format:

<timestamp> - visited from <ip>

To consume messages from Kafka:

docker exec -it <kafka-container-name> kafka-console-consumer \
  --bootstrap-server kafka:9092 \
  --topic url_visits --from-beginning

Replace with the name or ID of your running Kafka container (e.g., url_shortener-kafka-1).

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📂 Project Structure

.
├── db
│   ├── postgres.go
│   ├── redis.go
│   └── url.go
├── docker-compose.yml
├── Dockerfile
├── go.mod
├── go.sum
├── handlers
│   ├── redirect.go
│   └── shorten.go
├── init.sql
├── kafka
│   └── kafka.go
├── main.go
├── README.md
├── url_shortener
└── utils
    └── utils.go

---

Cleanup

docker compose down -v

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Test Results for 10K Virtual Users

         /\      Grafana   /‾‾/  
    /\  /  \     |\  __   /  /   
   /  \/    \    | |/ /  /   ‾‾\ 
  /          \   |   (  |  (‾)  |
 / __________ \  |_|\_\  \_____/ 

     execution: local
        script: load-test.js
        output: -

     scenarios: (100.00%) 1 scenario, 1000 max VUs, 1m0s max duration (incl. graceful stop):
              * default: 1000 looping VUs for 30s (gracefulStop: 30s)

WARN[0011] The test has generated metrics with 100080 unique time series, which is higher than the suggested limit of 100000 and could cause high memory usage. Consider not using high-cardinality values like unique IDs as metric tags or, if you need them in the URL, use the name metric tag or URL grouping. See https://grafana.com/docs/k6/latest/using-k6/tags-and-groups/ for details.  component=metrics-engine-ingester
WARN[0023] The test has generated metrics with 200637 unique time series, which is higher than the suggested limit of 100000 and could cause high memory usage. Consider not using high-cardinality values like unique IDs as metric tags or, if you need them in the URL, use the name metric tag or URL grouping. See https://grafana.com/docs/k6/latest/using-k6/tags-and-groups/ for details.  component=metrics-engine-ingester


  █ TOTAL RESULTS 

    checks_total.......................: 87354   2828.610657/s
    checks_succeeded...................: 100.00% 87354 out of 87354
    checks_failed......................: 0.00%   0 out of 87354

    ✓ Shorten status was 200
    ✓ Redirect status was 302
    ✓ Redirect location correct

    HTTP
    http_req_duration.......................................................: avg=24.23ms min=139.67µs med=1.52ms max=2.52s p(90)=14.51ms p(95)=26.71ms
      { expected_response:true }............................................: avg=24.23ms min=139.67µs med=1.52ms max=2.52s p(90)=14.51ms p(95)=26.71ms
    http_req_failed.........................................................: 0.00%  0 out of 58236
    http_reqs...............................................................: 58236  1885.740438/s

    EXECUTION
    iteration_duration......................................................: avg=1.04s   min=1s       med=1s     max=3.56s p(90)=1.02s   p(95)=1.06s  
    iterations..............................................................: 29118  942.870219/s
    vus.....................................................................: 1000   min=1000       max=1000
    vus_max.................................................................: 1000   min=1000       max=1000

    NETWORK
    data_received...........................................................: 11 MB  344 kB/s
    data_sent...............................................................: 8.7 MB 282 kB/s




running (0m30.9s), 0000/1000 VUs, 29118 complete and 0 interrupted iterations
default ✓ [======================================] 1000 VUs  30s