A simple example Telegram echo-bot on Google Cloud Functions

bot.go

package telegrambot

import (
	"context"
	"fmt"
	"os"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/go-telegram/bot"
	"github.com/go-telegram/bot/models"
)

func init() {
	token := os.Getenv("TELEGRAM_BOT_TOKEN")

	webhookURL := fmt.Sprintf("https://%s-%s.cloudfunctions.net/%s",
		os.Getenv("FUNCTION_REGION"), // e.g. "us-central1"
		os.Getenv("GCP_PROJECT"),     // e.g. "my-project"
		os.Getenv("FUNCTION_NAME"),   // e.g. "my-function"
	)

	// Define the bot's default handler
	opts := []bot.Option{
		bot.WithDefaultHandler(handler),
	}

	// Create a new bot with the default handler
	tgbot, err := bot.New(token, opts...)
	if err != nil {
		panic(err)
	}

	// Set the Webhook for the bot
	_, err = tgbot.SetWebhook(context.Background(), &bot.SetWebhookParams{
		URL: webhookURL,
	})
	if err != nil {
		panic(err)
	}

	// Register the bot's WebhookHandler with the Functions Framework
	functions.HTTP("bot", tgbot.WebhookHandler())

	// Start the bot with the Webhook
	go tgbot.StartWebhook(context.Background())
}

func handler(ctx context.Context, b *bot.Bot, update *models.Update) {
	b.SendMessage(ctx, &bot.SendMessageParams{
		ChatID: update.Message.Chat.ID,
		Text:   update.Message.Text,
	})
}