Go Serverless LINE Bot Demo

This is a LINE Messaging Bot written in Go using the LINE Messaging API SDK. The bot provides a webhook to be called by LINE.

The bot is "serverless" which means it runs using AWS Lambda and uses AWS API Gateway to expose the webhook endpoint.

Deployment uses the AWS Serverless Application Model, with the template and config provided.

Using this, you should be able to have a working LINE Bot up & running in less than 5 minutes. This demo bot will respond to any LINE text messages it receives with two reply messages: One echoing back the message text received and the sender's internal UserID, and the second with a dump (go's %+v) of the Message and Source objects received from LINE.

Deployment using AWS SAM

Prerequisites

You'll need:

• go installed (version 1.16 or newer)
• AWS SAM CLI installed
• AWS CLI credentials set-up
• Your "Channel Access Token" and "Channel Secret" for LINE Messaging API (get these from the LINE Developer Console)

Deploying to AWS

The deploy.sh script was tested on MacOS, and should work on Linux. You may need to adjust it if you are using Windows.

1. Execute ./aws-serverless/deploy.sh -g
2. Enter parameter values when prompted:

• ChannelSecret Your LINE API Channel Secret
• ChannelAccessToken Your LINE API Channel Access Token
• Enter Y if asked "Function may not have authorization defined, Is this okay?"
• Use the default values for the other parameters.

3. When the stack has finished deploying, it will show the WebhookUrl value in the outputs section. Please set and enable this URL as your webhook URL in the LINE Developer console.

A full deployment transcript is in the doc directory and there are some screenshots below.

Quick check with curl

Making a HTTP POST request to the WebhookUrl address should produce a reply with 200 status and an empty body:

$ curl -d '' -isS https://xdosk33669.execute-api.us-west-2.amazonaws.com/v1/line/hook

HTTP/2 200 
content-type: application/json
content-length: 0
date: Sat, 13 Mar 2021 16:59:08 GMT
x-amzn-requestid: 71ce2272-98a5-9999-a526-72bbd14e9f65
...

Screenshots

Set & enable the webhook URL in the LINE Developer console:

Bot replies in the LINE app:

Notes

• The LINE Messaging API SDK will validate the X-Line-Signature header when the webhook is called and that should ensure only LINE can sucessfully use the webhook.