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Learning Go: Days 2-4 - Uptime Tracker

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By thirtyone
1 min read
Learning Go: Days 2-4 - Uptime Tracker

Continuing the 30-day journey. Days 2-4 focused on building an uptime tracker for websites.

What is Uptime Tracker?

A Go application that monitors website availability. It periodically checks if websites are up or down and stores the results in a database. The datapoints are then shown on the UI. The system has three main components:

  1. Cronjob - Periodically checks website status
  2. Web Server - Serves the status data via API
  3. Frontend - Displays the status data

How It Works

Cronjob Component

Runs on a schedule and:

  • Fetches all tracked URLs from the database
  • Makes HTTP requests to each URL every second
  • Records whether each request succeeded (HTTP 200) or failed
  • Stores results in the database

Web Server Component

Provides an API endpoint:

  • GET /v1/trackers/status - Returns the last 60 status checks

Repository

sapienfrom2000s/uptime-tracker

Project Structure

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uptime-tracker/
├── backend/
│   ├── cronjob/
│   │   ├── go.mod
│   │   └── main.go
│   ├── webserver/
│   │   ├── go.mod
│   │   └── main.go
│   └── db/
│       └── sqlite.db
└── frontend/

Database Schema

Two tables:

Trackers - Stores URLs to monitor

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ID (INTEGER)
url (TEXT)

UptimeStatuses - Stores status check results

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ID (INTEGER)
tracker_id (INTEGER)
up (BOOLEAN)

Key Technologies

  • SQLite - Lightweight database for storing trackers and status history
  • Gin - Web framework for the API server
  • Robfig/Cron - Scheduling library for periodic checks

Cronjob Flow

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1. Connect to SQLite database
2. Query all tracked URLs
3. For each URL:
   - Create a cron job that runs every 1 second
   - Make HTTP GET request
   - Check if response status is 200 (OK)
   - Insert result into UptimeStatuses table
4. Run for 15 minutes (900 seconds)
5. Stop and exit

Web Server Flow

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1. Connect to SQLite database
2. Create Trackers table if it doesn't exist
3. Create UptimeStatuses table if it doesn't exist
4. Start Gin server with CORS enabled
5. Serve /v1/trackers/status endpoint
6. Return last 60 status checks as JSON array
Go, Learning
golang project learning-journey uptime-tracker sqlite cron
This post is licensed under CC BY 4.0 by the author.