URL Shortener

A URL shortener service written in Go that provides a simple API for shortening URLs and redirecting users. It uses MySQL as the database backend and integrates with Prometheus for monitoring.

Features

• Generate short URLs for long URLs.
• Redirect users from short URLs to their corresponding long URLs.
• Health check endpoints for readiness and liveness.
• Prometheus metrics integration.
• Profiling endpoints using pprof.
• Graceful shutdown of servers.

Prerequisites

• Go 1.16 or higher
• MySQL
• Docker (optional)

Installation

1. Clone the repository:

git clone https://github.com/paragor/url_shortener.git
cd url_shortener

2. Install dependencies:

go mod tidy

3. Set up a MySQL database and create a DSN (Data Source Name) for connecting to it. You can use the environment variable MYSQL_DSN to configure the DSN.

Configuration

The application can be configured using command-line flags or environment variables:

Flag	Environment Variable	Default	Description
-short-url-scheme	SHORT_URL_SCHEME	https	Scheme of the shortened URL.
-short-url-domain	SHORT_URL_DOMAIN		Domain for the shortened URL.
-short-url-path	SHORT_URL_PATH	/	Path prefix for the shortened URL.
-short-url-size	SHORT_URL_SIZE	5	Number of characters in the short URL.
-listen-addr	LISTEN_ADDR	:8080	Address to listen on for HTTP requests.
-diagnostic-addr	DIAGNOSTIC_ADDR	:7070	Address to listen on for diagnostics.
-mysql-dsn	MYSQL_DSN	user:password@tcp(127.0.0.1:3306)/dbname?parseTime=true	DSN for MySQL connection.
-run-migration		false	Run migrations on startup.

Usage

1. Build the application:

go build -o url_shortener main.go

2. Run the application:

./url_shortener -short-url-domain "yourdomain.com" -mysql-dsn "your-mysql-dsn"

You can also use environment variables to configure the application:

export MYSQL_DSN="user:password@tcp(127.0.0.1:3306)/dbname?parseTime=true"
./url_shortener -short-url-domain "yourdomain.com"

3. The application will start two servers:
   • Main server for handling API requests (default :8080).
   • Diagnostic server for health checks and metrics (default :7070).

API Endpoints

Generate Short URL

• Endpoint: /api/v1/generate_short_url
• Method: POST or PUT
• Request Body:

{
"long_url": "http://example.com",
"ttl_seconds": 3600
}

if ttl_seconds = 0, means link is forever exists

• Response:

{
"short_url": "https://yourdomain.com/abc12"
}

Redirect Short URL

• Endpoint: /{short_url}
• Method: GET

Redirects to the original long URL.

Health Checks

• Readiness Probe: /readyz
• Liveness Probe: /healthz

Prometheus Metrics

• Endpoint: /metrics

Profiling

Profiling is enabled via pprof on the diagnostic server:

• Endpoint: /debug/pprof/

Monitoring and Profiling

The application integrates with Prometheus for monitoring metrics. The /metrics endpoint exposes metrics that can be scraped by Prometheus.

Additionally, Go's built-in pprof tool is enabled on the diagnostic server for profiling and debugging purposes.

Running Migrations

To run database migrations, start the application with the -run-migration flag:

./url_shortener -run-migration