poc-telegram-bot-aws-lambda

A Proof of Concept Telegram Boy running on AWS Lambda

• What to test it? Message AWSLambdaBot
• Want the long setup instructions? With pictures? See the Snowulf blog

Setup - The short version

• Register a Telegram Bot per https://core.telegram.org/bots#botfather
• Create two Lambda functions, one for each of the js files
• Change the 'botAPIKey' to your new bots API key
• Allocate 1024MB of memory per function, for faster running
• Create a DynamoDB table
• Name: telegramlog
• Key type: hash and range
• Hash key: username
• Range key: updateid
• Provisioned read: 5
• Provisioned write: 2
• Create two AWS API Gateway resources of /telegram (with post) and /setwebhook (with post)
• the /setwebhook api should point to the Lambda function for setTelegramWebhook.js
• the /telegram api should point to the Lambda function for telegramEcho.js
• curl -H "Content-Type: application/json" -X POST -d "{\"url\":\"https://YOURURL.execute-api.us-west-2.amazonaws.com/main/telegram\"}" https://YOURURL.execute-api.us-west-2.amazonaws.com/main/setwebhook/
• You should see a response of {"ok":true,"result":true,"description":"Webhook was set"}
• Message your bot!
• It should respond and you should be able to see the log entry in your DynamoDB table.

FAQ

• Q. Aren't there lots of NPM modules for Telegram bots? Why didn't you use one?

• A. Because I wanted to understand everything that was happening for this proof of concept.

• Q. Is this the "best" way to make a Telelgram/Lambda bot?

• A. I really hope not, again, just a POC to show that it can easily be done.

• Q. How do I make my bot stateful in Lambda?

• A. Lambda is inherently stateless, so you'll need to store state info in a database.

• Q. How many users will this support?

• A. It's the cloud my friends, Lambda should theoretically be able to support an unlimited number of simultaneous hits. Your limiting factor would be Dynamo read/write (in this example).

• Q. Do you need to use Lambda to set the webhook?

• A. No, you don't. You could just curl it directly (in fact, that'd probably be easier), however I did it because I wanted to have an "All in Lambda" bot. If I made a real bot, I'd want to be able to set it's own webhooks.

• Q. How do I send messages at times other than when the user messages the bot?

• A. I presume you want to be able to do things like set timers or notifications? Well, with this code you can't. If you had a Lambda function that was triggered by a webcron or some other webhook, it could send messages as the bot. Once a user has messaged the bot for the first time, all you need is their user id to send them messages later.

• Q. How does this bot handle /slash commands?

• A. It doesn't. It's the bot equivalent of "Hello ".

• Q. Where can I learn more about Telegram bots?

• A. See the Telegram Bot API docs