Telegram Bot as a Function

Project template to easily create a Telegram bot as an AWS Lambda function.

The template uses serverless-offline and ngrok to make the development easy before you deploy it to AWS.

Configuring Telegram BOT

You need to contact the Telegram @BotFather to create your bot and get the token to use as an ENV here.

Developing

You can use a .env or

TELEGRAM_TOKEN=telegram_bot_token npm run dev

This will start the serverless-offline and ngrok at the same port configured on PORT||3000 env. After the server is up, you can send messagens directly through telegram to your local machine.

Env vars:

Required:

• TELEGRAM_TOKEN token from the @BotFather
• DEBUG comma separated namespaces to activate debug log

Optional:

• PORT||3000 ngrok tunnel and serverless-offline port

Commands

On handler.js add a new command as a regex which even accepts named grouping as handlers parameters.

One important thing is handler order. The bot returns on the first handler match, so, if you have two different handlers to the same path, and one accepts parameters, put the one with parameters firts.

Simple command example:

// handler.js
const mycommand = require('./src/commands/mycommand')

...

bot.on(/\/mycommand/, mycommand) // mycommand handler should be a generator that yields messages
                                 // to be  sent back to telegram

// mycommand.js
async function* handler(message) {
  yield `hi ${message.from.first_name} from my command`
}

Named param command example:

// handler.js
const mycommand = require('./src/commands/mycommand')

...

bot.on(/\/mycommand (?<action>action1|action2) (?<opt>op1|op2)/, mycommand) // 

// mycommand.js
async function* handler(message, { action, opt }[, match]) {// match is the regex.exec(text) return
  yield `hi ${message.from.first_name} from my command. You want to do action ${action} with option ${opt}`
  // match[0] === action, match[1] === opt
}

Positional param command example:

// handler.js
const mycommand = require('./src/commands/mycommand')

...

bot.on(/\/mycommand (param1|param2) (opt1|opt2)/, mycommand) // 

// mycommand.js
async function* handler(message, match) {// match is the regex.exec(text) return
  yield `hi ${message.from.first_name} from my command. You want to do action ${match[0]} with option ${match[1]}`
}

Deploy

The deployment is already configured to use GitlabCI. If you don't use it, you can deploy using the serverless framework from your local machine.

Configure the required environment variables above and the following:

• AWS_ACCESS_KEY_ID your AWS service user Access Key Id
• AWS_SECRET_ACCESS_KEY your AWS service user Secret Access Key

GitlabCI

git push origin master

Local machine

One time configuration:

npm run config

Every deploy:

npm run deploy