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https://github.com/carlo-colombo/serverless-telegram-bot-gc-functions


https://github.com/carlo-colombo/serverless-telegram-bot-gc-functions

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README 

        
# Serverless Telegram Bot on Google Cloud Functions



### Prerequisites

* Goole Cloud account and a project. https://cloud.google.com/resource-manager/docs/creating-managing-projects

* Enable Google Cloud Functions and RuntimeConfig API from the API manager.

* Get a telegram bot token, ask it to the [BotFather](https://telegram.me/BotFather).



#### Warning

* Both Google Cloud Functions and RuntimeConfig are both still in beta.

* Even if the GCP free tier is quite inclusive some costs can be billed.



### The token



```bash

# export for local testing 

export TELEGRAM_TOKEN=133545asdasd



# set the token as GC runtime configuration 

gcloud beta runtime-config configs create prod-config

gcloud beta runtime-config configs variables \

    set telegram/token  "$TELEGRAM_TOKEN" \

    --config-name prod-config

```



### The bot



```js

exports.echoBot = function(req, res){

    /*

     * When the request set the content-type header to application/json

     * the body of the request does not need to be parsed and is already

     * available as object.

     */

    const {message:{chat, text}} = req.body

    const echo = `echo: ${text}`



    return getToken()

        .then( token => request.post({

            uri: `https://api.telegram.org/bot${token}/sendMessage`,

            json: true,

            body: {text: echo, chat_id: chat.id}

        }))

        .then(resp => res.send(resp))

        .catch(err => res.status(500).send(err))

}



```

Just an easy bot that echos the received message.



### Retrieving the token



This function return a (promise) of a token either from the runtime config api when run online or from

an environment variable when run locally. The value is retrieved using 

[fredriks/cloud-functions-runtime-config](https://github.com/fredriks/cloud-functions-runtime-config) that wraps the api.

`NODE_ENV` is set to production when the function is run online, thus allow to discriminate in which environment

the function run.



```js

function getToken(){

    if (process.env.NODE_ENV == 'production'){

        return require('cloud-functions-runtime-config')

            .getVariable('prod-config', 'telegram/token')

    }

    return Promise.resolve(process.env.TELEGRAM_TOKEN)

}

```



### Local testing



Google provide a local emulator for Functions feature. It allow to local deploy a function to iterate

over it without having to deploy to the google server. It reload the code when changed on the file system

so it is not necessary to redeploy after the first time.



```

npm -g install @google-cloud/functions-emulator



functions start

functions deploy echoBot --trigger-http



curl -X POST \

  -H "Content-Type: application/json" \

  -d '{

     "message": {

       "chat": {

         "id": 1232456

       },

       "text": "hello world"

     }

   }' \

   http://localhost:8010/PROJECT_ID/us-central1/echoBot



# To tail logs

watch functions logs read



```



### Deploying



Before deploy the function is required to create a Cloud Storage bucket where the function will be stored



```bash

gsutil mb -c regional -l us-central1 gs://unique-bucket-name



gcloud beta functions deploy function_name \

  --trigger-http \

  --entry-point echoBot \

  --stage-bucket unique-bucket-name

```



### Set up the webhook



Deploying the function with the http trigger will return an url to trigger the function. The url would look

like `https://-.cloudfunctions.net/function_name`. Use this url to set up a web hook

for your bot on telegram. You can check more information on webhook on the

[Telegram API documentation](https://core.telegram.org/bots/api#setwebhook)



```bash

curl -X POST \

  -H "Content-Type: application/json" \

  -d '{

     "url": "https://-.cloudfunctions.net/function_name"

   }' \

   https://api.telegram.org/bot${TELEGRAM_TOKEN}/setWebhook

```