Developing a Simple Python Telegram Bot

Overview

• Presenter: Federico Tartarini
• Objective: Create a basic Python bot that echoes user messages
• Tool: Python Telegram Bot Library, Google Cloud Functions

Why Google Cloud Functions?

• Avoids continuous running costs associated with using a server
• Automatically triggered by a webhook
• No server maintenance, patching, or updates required

Prerequisites

• Google Cloud Platform (GCP) account
  • Must enable billing, provide credit card details (likely won't be charged for light use)
• Python installed on your computer
  • Install from Python's website
  • Can use PyCharm for setup
• Google Cloud SDK installed on your computer
  • Follow installation instructions based on your OS
• Telegram account
  • BotFather interaction to create a new bot

Creating a Telegram Bot

1. In Telegram: Search for BotFather
   • Use command /newbot
   • Name your bot and set a username (unique)
   • Save the API key generated (keep it secret)
   • Example: example_youtube_video_bot
2. Find or create your bot and save its username

Setting Up Your Python Environment

1. Open PyCharm
   • Create a new project
   • Name it (e.g., telegram_example)
   • Set base interpreter to Python 3.8
   • Create virtual environment (no global site packages)
2. Add files:
   • main.py: import os from telegram import Bot def telegram_bot(request): bot = Bot(token=os.environ['TELEGRAM_TOKEN']) if request.method == 'POST': update = request.get_json() chat_id = update['message']['chat']['id'] text = update['message']['text'] bot.send_message(chat_id=chat_id, text=text) return 'OK'
   • .gitignore: Standard Python and PyCharm exclusion
   • .gcloudignore: Exclude .gitignore, README.md, and other unnecessary files for deployment
   • requirements.txt: Should include python-telegram-bot

Deploying on Google Cloud Functions

1. Using the GCP Console:
   • Create a new project if not already existing
   • Note the project ID
2. Deploy the function via terminal with gcloud: gcloud functions deploy telegram_bot \ --runtime python38 \ --trigger-http \ --set-env-vars TELEGRAM_TOKEN=<your-api-key> \ --project=<your-project-id>
   • Authenticate if prompted
   • Allow unauthenticated invocation
3. Set the Telegram Webhook: curl -F "url=https://<your-cloud-function-url>" https://api.telegram.org/bot<your-api-key>/setWebhook

Testing the Bot

• Send a message to your new bot, it should reply with the same message
• Example: Send "Ciao", receive "Ciao" back

Modification Example

• Inside main.py, modify the content returned by the bot: def telegram_bot(request): bot = Bot(token=os.environ['TELEGRAM_TOKEN']) if request.method == 'POST': update = request.get_json() chat_id = update['message']['chat']['id'] text = update['message']['text'] + ' from the bot' bot.send_message(chat_id=chat_id, text=text) return 'test'
• Deploy changes and test again

Conclusion

• Ensure proper setup and deployment as guided
• Check the response to confirm the bot's functionality
• Refer to the Python Telegram Bot library and Google Cloud documentation for more advanced features and configurations

Resources

• Python Telegram Bot Library
• Google Cloud Functions
• PyCharm

Troubleshooting

• Ensure proper API key usage and secrecy
• Verify GCP billing is enabled and account is active
• Follow logs and error messages when deploying to debug issues