AWS-Telegram-Bot-Example-Java

Telegram bot
Webhook on AWS-Lambda
Implemented in Java with Gradle
gradle-aws-plugin is used to install and update lambdas
TelegramBots library is used to parse updates and to send messages

About

Just an example (and a template) of how easily you can create a Telegram bot hosted on AWS-Lambda service as webhook.

Result bot can't do much, it just sends you its version in response to /version message, or echoes any other message.

Usage

Gradle plugin allows you to easily create and update the lambda function. In order to use it, you have to have an Amazon AWS account. Then you need to create an access key for your account and to configure the AWS CLI on your dev machine. This will give you the "profile name" that you need to specify in your gradle script:

aws {
    profileName = 'default'
}

Then you can configure your future (or existing) lambda parameters:

def lambda_name_test = "MyBotTestLambdaName"
def lambda_name_production = "MyBotProductionLambdaName"
def lambda_role = "arn:aws:iam::${aws.accountId}:role/lambda-role"
def lambda_handler = "com.vsubhuman.telegram.java_example.Main"

Note! That if you already have a prepared lambda, then you only have to specify its name! All the other properties are only required for lambda installation.

Note2! The specified role must exist, or build will fail! You may manage roles in the IAM console.

Handler points to the class that implements the lambda interface and that will be used as the entry point.

Create lambda

When all parameters are set you may call commands:

gradle install_lambda

gradle install_lambda_production

These commands will attempt to create a new lambda with either test or production name respectively, and to deploy current code.

Update lambda

After you already got an existing lambda and you just want to update its code, call:

gradle deploy

gradle deploy_production

In order to build an uberjar and to upload it to either test or production lambda respectively.

`bot_token` & `bot_username`

Note! That your lambda must have an environment properties:

bot_token - the telegram token of your either test or production bot. 2 bot_username - the username of your either test or production bot

These properties are required to configure AbsSender utility, that provides nice API to send messages from bot.

You may find and configure youe lambda function in the console: https://console.aws.amazon.com/lambda/home

API Gateway

Once lambda is ready and running, you need to create two publicly available endpoints in order for telegram to be able to send you updates. You can manage it with API-Gateway console

You may create a single API with two resources: POST /test and POST /prod, and wire those methods to call your test and production lambdas respectively. You also may include your telegram bot token into resource path as Telegram suggests

NOTE! Do not forget to stage your AWS-API when you done configuring it. The staging will provide you with the fully qualified URL address of the created resources.

Set webhook

When you have your API staged, you need to register URL addresses in the Telegram, so they will know where to send all the updates for your bot. You can do it by sending a POST request like this:

curl -X POST "https://api.telegram.org/bot${token}/setWebhook?url=${aws_url}"

Insert the token of your bot and the corresponding URL address and you good to go. After successull request like that - your lambda should start to receive all the messages sent to your bot.

Fire up

Note that when you call your bot first time after an update, or ufter a long time pause - it needs a time to fire up your lambda environment. Amazon actually starts up a lambda only when it's called and kills it when it not called for some time.

So give it a few seconds.

Logs

Do not forget that a LogGroup with a name /aws/lambda/${LambdaName} is automatically created for each lambda. You can find logs in CloudWatch console

vsubhuman/aws-telegram-bot-example-java