🔗 URL Shortener Telegram Bot

A simple and fast Telegram bot for shortening URLs, written in Go.
You send a link — the bot returns a short one. That’s it.

📝 Author's Note

This is a learning project demonstrating interaction with the Telegram Bot API, Supabase, caching, HTTP, and context.
Service architecture built using the Dependency Injection (DI) pattern.

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📲 How It Works

Before this you must run the service according to the instructions below

1. Open the Telegram bot.
2. Tap “Shorten URL”.
3. Send any link (e.g., https://example.com/some/very/long/url).
4. The bot will return a shortened version like "your_protocol://your_host_name/hash" (e.g., http://short.ly/128429213).
5. Follow the link — and you’ll be redirected to the original site.

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⚙️ Database Pre-Setup

Create database in Supabase without any tables, In table editor select schema public. Go to the SQL Editor and paste the following code:

create or replace function table_exists(tbl text)
returns boolean
language plpgsql
as $$
begin
  return exists (
    select from pg_tables
    where tablename = tbl
  );
end;
$$;

create or replace function execute_sql(sql text)
returns void
language plpgsql
as $$
begin
    execute sql;
end;
$$;

grant execute on function execute_sql(text) to service_role;
grant execute on function table_exists(text) to service_role;
grant create, usage on schema public to service_role;

It allows table creation via RPC: add functions for execute sql and check table exists.

⚙️ Project Pre-Setup

Go to the root folder and paste the following code:

/url-shorter-bot

go mod tidy

Download project dependency

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🚀 Launch

The bot can be launched in two ways: manually via YAML or using Docker.

🔧 Option 1: config.yaml (Manual)

Create a config.yaml file in the root of the project:

host_name: "YOUR_HOST_NAME"         # Default: "localhost"
port: "YOUR_PORT"                   # Default: "80" ("80" for HTTP or "443" for HTTPS)
tg_key: "YOUR_TELEGRAM_TOKEN"
db_url: "YOUR_SUPABASE_URL"
db_key: "YOUR_SUPABASE_SERVICE_ROLE_API_KEY"

You can get the service role key like this in Supabase project: Project settings -> Api Keys -> Api keys -> sevice_role

To get a telegram bot token, you must first create it. You can do this here

Then run it manually:

/url-shorter-bot

go run src/main.go

🐳 Option 2: Run via Docker

You can also run it using the run.sh script by passing variables:

/url-shorter-bot

TG_KEY=your_telegram_token \
DB_URL=https://your-project.supabase.co \
DB_KEY=your_supabase_service_role_key \
./run.sh

If host_name and port are not specified, default values are used:

host_name: localhost

port: 80 (HTTP protocol)

/url-shorter-bot

TG_KEY=your_telegram_token \
DB_URL=https://your-project.supabase.co \
DB_KEY=your_supabase_service_role_key \
HOST_NAME=your_host_name \
PORT=443 \
./run.sh

In this case, port 443 is used, which by default is open for HTTPS requests — so the program assumes you're using HTTPS.

📌 To work correctly, you need a real domain listed in the HostWhitelist and a DNS A record pointing to its IP address.

📌 You can also specify your custom port, but in response you will receive not http://your_domain/short_url, but http://your_domain:your_port/short_url

📌 However, it still works great with the default values in the YAML config using the HTTP protocol.

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🗄️ Database Tables

Tables are created automatically with RLS.

Table	Purpose
users	List of Telegram users
urls	Stores original and shortened links
log_error	Error log
log_action	User action log

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🧪 Testing

Only unit tests are written. No integration or end-to-end tests available yet.

Run tests:

/url-shorter-bot

go test run ./...

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📝 License

This project is licensed under the MIT License.

You are free to use, modify, and distribute it.