beldar / echo-assistant

A nodejs + typescript implementation of the Google Assistant as an Alexa Skill

echo-assistant

Overview

This is a nodejs + typescript Alexa Skill interfacing with the Google Assistant. It uses the alpha sdk, so it may stop working with major revision changes.

It uses Amazon Polly to translate text into voice that its send to the Assistant SDK, and the resulting audio is encoded and stored on a Amazon S3 bucket for later playback on the Amazon Echo (Alexa).

Features

• S3 Bucket creation with 1 day expiry lifecycle
• All transformation/communication is done using streams without writing to disk (wich makes it quite fast)
• Lots of debugging information
• Modular and clean code
• Builds dependencies for Lambda using Docker
• Zips the code ready to upload to Lambda
• Least amount of configuration by using Lambda roles to connect to S3 and Polly
• Account linking from Alexa to Google to generate the OAuth2 token

Considerations

• When running this code on AWS Lambda context the node modules with bindings of this project need to be compiled for Linux instead of MacOS or Windows, therefore before zipping and uploading this to AWS you need to do that extra step (if you're not already in Linux). There is a little script just to do that on app/build-deps.ts, which you can invoke with yarn build:deps.

• You can use the payload.json file as a tests event on Lambda.

• You'll need some environmental variables set up to make it run:

# Amazon S3 for transient audio file storage
AWS_S3_BUCKET     # Bucket name, could be anything but unique

# Google Assistant credentials
ASSISTANT_CLIENT_ID     # Client Id
ASSISTANT_CLIENT_SECRET # Secret
REDIRECT_URL            # oAuth2 redirect url

# Alexa
APP_ID    # Application ID

# Internal app vars
DEBUG        # Debug key (default: 'node-assistant')

Installation

I use yarn, but you should be able to use npm.

If you want to use yarn just install it globally:

npm i yarn -g

And then on the root folder:

yarn install

Build

Build scripts:

yarn build       # Copies files and compiles ts into js on dist/
yarn build:watch # Build and watch files to recompile
yarn build:deps  # Build node dependencies for lambda (linux) on the dist folder (uses docker)
yarn build:zip   # Create a zip file with the code on dist/app (ready to upload to lambda)
yarn build:all   # Do all of the previous tasks in one go

Debugging

All logging goes through node-debug, so you need to set the environmental variable before running it:

DEBUG=node-assistant node index

which tells it to turn debugging on.

Running

To run it:

yarn start

To run it in test mode instead of lamda mode run:

TESTING=true yarn start

The first time you'll need to uncomment the line where auth.getNewCredentials(); is called, and comment everything below it, to create a new creds.json file with the Google OAuth2 token.

Thanks

To @rvowles for his amazing repo which I forked and allowed me to make this work quicker