janken-bot for Slack

This application demopnstrates the implementation of Slack app to play Janken game (paper-scissors-rock).

Tech stack

• Runtime: Node.js
• Framework: Bolt - Slack's official chat app framework
• Database: Firestore
• Infrastructure: Google App Engine
• CI/CD: GitHub Actions

Setup local env

Prerequisites

• Slack app is created
• GCP project is created

Set the Bot Token Scopes at the Slack app web console

OAuth & Permissions > Scopes > Bot Token Scopes

Add the following scopes.

• chat:write
• chat:write.public
• commands

Configure the environment variables

$ cp .env.sample .env
$ vi .env

Set the following variables.

Key	Value
SLACK_SIGNING_SECRET	Slack app web console > Basic Information > App Credentials > Signing Secret
SLACK_BOT_TOKEN	Slack app web console > OAuth & Permissions > Bot User OAuth Access Token

Add the Service Account Key of GCP to access Firestore

Obtain a service account key from the GCP console.

IAM & Admin > Service Accounts > Select project > Service account of firebase-adminsdk > Actions > Create key

Rename the file to firestore_service_account_key.json and place it in the credentials directory.

Install package dependencies

$ npm install

Start local env

$ npm run dev

You ngrok URL will be output.

Set URLs at the Slack app web console

Slash Commands

Slash Commands > Create New Command

• Command: /janken_dev
• Request URL: (Your ngrok URL)/slack/events
• Escape channels, users, and links sent to your app: On

Interactivity & Shortcuts

Interactivity & Shortcuts > Interactivity > Request URL

• URL: (Your ngrok URL)/slack/events

Setup for OAuth mode

If you use the OAuth flow to install your app, the following setup is needed in addition to above.

Environment variables

Add the following variables to .env file.

Key	Value
SLACK_OAUTH_ENABLED	1
SLACK_CLIENT_ID	Slack app web console > Basic Information > App Credentials > Client ID
SLACK_CLIENT_SECRET	Slack app web console > Basic Information > App Credentials > Client Secret
SLACK_STATE_SECRET	This can be a random string. This is used in the OAuth flow.
ENCRYPTION_KEY	This can be a random string of 32 Bytes. This is used in encrypt/decrypt tokens.
BUFFER_KEY	This can be a random string of 16 Bytes. This is used in encrypt/decrypt tokens.

OAuth redirect URL at the Slack app web console.

OAuth & Permissions

OAuth & Permissions > Redirect URLs > Add New Redirect URL

URL: (Your ngrok URL)/slack/oauth_redirect