Blackout Bot — Telegram bot · serverless

Serverless Telegram bot that watches DTEK power-outage schedules and posts a rendered PNG card to a group whenever a day is added or changed.

Role: Author

Client: Personal tool, shared with neighbours

Team: Solo

Period: 2026

During scheduled blackouts in the Kyiv region, DTEK publishes outage plans per queue and often revises them during the day. Checking the site by hand is tedious, and it sits behind Imperva with hCaptcha, which blocks automated clients. The goal was a Telegram group that tells neighbours when the power will be off for their queue — only when something actually changes, and in a format readable at a glance on a phone.

I built it as a Cloudflare Worker on a 10-minute cron trigger. Instead of fighting the captcha, it reads a public JSON mirror of the DisconSchedule object embedded in DTEK’s page, takes the days from today for the configured queues and diffs them against a snapshot in Workers KV. When a new day appears or a schedule changes, an HTML card with half-hour slots is rendered to PNG through Cloudflare Browser Rendering (Playwright) and sent with a caption summarising outage windows and total hours.

Cron Worker every 10 minutes with state in Workers KV

Posts only when a new day appears or a schedule changes

PNG schedule card rendered via Cloudflare Browser Rendering

Several queues in one message; possible outages flagged

Stale-data alerts at most once per 12 hours; manual run endpoints

In use since October 2026 by a residents’ Telegram group; image rendering stays within the free tier

TypeScript, Cloudflare Workers, Cron Triggers, Workers KV, Browser Rendering, Playwright, Telegram Bot API, Wrangler