telega_mist

Mist webhook adapter for Telega Telegram Bot Library.

A minimal webhook adapter built directly on top of mist, without wisp. Use it for lightweight deployments where you don’t need a full web framework. If you already use wisp, prefer telega_wisp.

Installation

gleam add telega_mist

Usage

telega_mist provides a handle_bot handler that plugs into your mist request handler. It validates the secret token, decodes incoming Telegram updates, and dispatches them to your bot.

import gleam/bytes_tree
import gleam/erlang/process
import gleam/http/request.{type Request}
import gleam/http/response.{type Response}
import mist.{type Connection, type ResponseData}
import telega.{type Telega}
import telega_mist

fn handle_request(
  req: Request(Connection),
  bot: Telega(session, error),
) -> Response(ResponseData) {
  use <- telega_mist.handle_bot(telega: bot, req:)

  // Your other routes here...
  response.new(404)
  |> response.set_body(mist.Bytes(bytes_tree.new()))
}

pub fn main() {
  let assert Ok(bot) = // ... build and init your Telega bot for webhooks

  let assert Ok(_) =
    fn(req) { handle_request(req, bot) }
    |> mist.new
    |> mist.port(8000)
    |> mist.start

  process.sleep_forever()
}

The handler will:

1. Check if the request matches the bot’s webhook path
2. Validate the x-telegram-bot-api-secret-token header
3. Decode the update and pass it to the bot asynchronously
4. Return 200 OK immediately so Telegram doesn’t retry

Use handle_bot_with_limit to override the maximum request body size (defaults to 4MB).

Requirements

• Gleam >= 1.12.0
• Erlang target only