Serverless Messenger Bot Boilerplate by

Facebook has sunset stories in Wit.ai. This boilerplate will no longer function due to this

More at https://wit.ai/blog/2017/07/27/sunsetting-stories

The Objective

Create a Facebook Messenger chatbot using Serverless Framework to build backend for the service.

Objective chart

User sends message from Facebook Messenger to Facebook Messenger API which forwards it to the AWS API Gateway
AWS API Gateway triggers Lambda function facebookBot which sends the message forward to the SNS topic witAiTopic
Lambda function witAiHandler, which subscribes to the witAiTopic SNS topic, receives the message, forwards it to wit.ai, processes actions required by the bot (e.g. fetch data from 3rd party services) and posts the response to the SNS topic fbMessengerTopic that forwards message to wit.ai which processes it and returns context
Lambda function facebookBot subscribes to the fbMessenger topic. It receives the message sent by witAiHandler and forwards it the the Messenger Platform
User receives the response to the message

Boilerplate Installation

Run serverless install --url https://github.com/SC5/serverless-messenger-boilerplate
Run npm install
Rename example.env to .env and fill in FACEBOOK_BOT_VERIFY_TOKEN
Run serverless deploy then copy the GET endpoint url

Facebook App Configuration

In Facebook Developer site create new Facebook application and page

Create Facebook application -> https://developers.facebook.com/quickstarts/?platform=web
Create Facebook page -> https://www.facebook.com/pages/create

Go to the App Dashboard and under Product Settings and setup webhook by clicking Setup Webhooks

Callback URL -> url from step 4
Verify Token -> from step 3
Select Subscription field messages (select message_deliveries, messaging_optins, and messaging_postbacks only if you plan to implement functionality related to opt-ins, delivery / read receipts or postbacks)
At this stage, the application is available only for developers and testers. The application needs to be approved by Facebook for public access

Click Verify and Save
In the Token Generation section, select the page created in step 5 and copy the generated token
In Webhooks section, select page created in step 5 to be the one that subscribes the webhooks
Paste token copied in step 8 to .env file as FACEBOOK_BOT_PAGE_ACCESS_TOKEN

More detailed instructions for Facebook Messenger platform configuration can be found from https://developers.facebook.com/docs/messenger-platform/quickstart/

Run serverless deploy
Open Facebook page created in step 1 and send message "Hello" to it

Wit.ai Configuration

Following steps are slightly modified version of https://wit.ai/docs/quickstart

Register to wit.ai https://wit.ai
Click + icon located in top menu to create a new app
Type in app name and description
If you wish you can change language and data privacy
Select settings
Copy App ID
Paste token to .env file as WIT_AI_TOKEN
Implement wit.ai flow

Testing

The serverless-mocha-plugin module is included in the boilerplate. You can invoke tests locally with

serverless invoke test (for all test)
serverless invoke test -f facebookBot (to run only the facebookBot tests)
serverless invoke test -f witAiHandler (to run only the witAiHandler tests)

Implement the test cases for your bot to test/witAiHandler.js. By default, the tests are run silently (not forwarded to Messenger). If you want to run full tests, comment out the row process.env.SILENT = 1; from the tests test/*.js.

Final Touch

Run serverless deploy
Open Messenger and search you bot
Now you can converse with your bot