Slack Ruby Bot Server

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Build a complete Slack bot service with Slack button integration, in Ruby.

If you are not familiar with Slack bots or Slack API concepts, you might want to watch this video.

A good open-source demo of a service built on top of this library is Strava integration with Slack.

Table of Contents

What is this?

A library that contains a Grape API serving a Slack Ruby Bot to multiple teams. This gem combines a web server, a RESTful API and multiple instances of slack-ruby-bot. It integrates with the Slack Platform API. Your customers can use a Slack button to install the bot.

Stable Release

You're reading the documentation for the stable release of slack-ruby-bot-server, 0.12.3. See UPGRADING when upgrading from an older version.

Try Me

A demo version of the sample app with mongoid is running on Heroku at slack-ruby-bot-server.herokuapp.com. Use the Add to Slack button. The bot will join your team as @slackbotserver.

Once a bot is registered, you can invite to a channel with /invite @slackbotserver interact with it. DM "hi" to it, or say "@slackbotserver hi".

Run Your Own

You can use one of the sample applications to bootstrap your project and start adding slack command handlers on top of this code. A database is required to store teams.

MongoDB

Use MongoDB with Mongoid as ODM. Configure the database connection in mongoid.yml. Add the mongoid gem in your Gemfile.

gem 'mongoid'
gem 'kaminari-mongoid'
gem 'mongoid-scroll'
gem 'slack-ruby-bot-server'

See the sample app using Mongoid for more information.

ActiveRecord

Use ActiveRecord with, for example, PostgreSQL via pg. Configure the database connection in postgresql.yml. Add the activerecord, pg, otr-activerecord and cursor_pagination gems to your Gemfile.

gem 'pg'
gem 'activerecord', require: 'active_record'
gem 'slack-ruby-bot-server'
gem 'otr-activerecord'
gem 'cursor_pagination'

See the sample app using ActiveRecord for more information.

Usage

Start with one of the samples above, which contain a couple of custom commands, necessary dependencies and tests, then create a new Slack App.

Follow Slack's instructions, note the app client ID and secret, give the bot a default name, etc. The redirect URL should be the location of your app. For local testing purposes use a public tunneling service such as ngrok to expose local port 9292.

Within your application, edit your .env file and add SLACK_CLIENT_ID=... and SLACK_CLIENT_SECRET=... in it.

Run bundle install and foreman start to boot the app. Navigate to localhost:9292. You should see an "Add to Slack" button. Use it to install the app into your own Slack team.

OAuth Code Grant

The "Add to Slack" button uses the standard OAuth code grant flow as described in the Slack docs.

The button itself contains a link that looks like this:

https://slack.com/oauth/authorize?scope=bot&client_id=<%= ENV['SLACK_CLIENT_ID'] %>

Once clicked, the user is taken through the authorization process at Slack's site. Upon successful completion, a callback containing a temporary code is sent to the redirect URL you specified. The endpoint at that URL contains code that looks like this:

# Instantiate a web client
client = Slack::Web::Client.new

# Request a token using the temporary code
rc = client.oauth_access(
  client_id: ENV['SLACK_CLIENT_ID'],
  client_secret: ENV['SLACK_CLIENT_SECRET'],
  code: params[:code]
)

# Pluck the token from the response
token = rc['bot']['bot_access_token']

The token is stored in persistent storage and used each time a Slack client is instantiated for the specific team.

API

This library implements an app, SlackRubyBotServer::App, a service manager, SlackRubyBotServer::Service that creates multiple instances of a bot server class, SlackRubyBotServer::Server, one per team. It also provides default HTML templates and JS scripts for Slack integration.

App

The app instance checks for a working database connection, ensures indexes, performs migrations, sets up bot aliases and log levels. You can introduce custom behavior into the app lifecycle by subclassing SlackRubyBotServer::App and creating an instance of the child class in config.ru.

class MyApp < SlackRubyBotServer::App
  def prepare!
    super
    deactivate_sleepy_teams!
  end

  private

  def deactivate_sleepy_teams!
    Team.active.each do |team|
      next unless team.sleepy?
      team.deactivate!
    end
  end
end

MyApp.instance.prepare!

Service Manager

Lifecycle Callbacks

You can introduce custom behavior into the service lifecycle via callbacks. This can be useful when new team has been registered via the API or a team has been deactivated from Slack.

instance = SlackRubyBotServer::Service.instance

instance.on :started, :stopped do |team|
  # team has been started or stopped
end

instance.on :created do |team, error, options|
  # a new team has been registered
end

instance.on :deactivated do |team, error, options|
  # an existing team has been deactivated in Slack
end

instance.on :error do |team, error, options|
  # an error has occurred
end

The following callbacks are supported. All callbacks receive a team, except error, which receives a StandardError object.

callback description
error an error has occurred
creating a new team is being registered
created a new team has been registered
booting the service is starting and is connecting a team to Slack
booted the service is starting and has connected a team to Slack
stopping the service is about to disconnect a team from Slack
stopped the service has disconnected a team from Slack
starting the service is (re)connecting a team to Slack
started the service has (re)connected a team to Slack
deactivating a team is being deactivated
deactivated a team has been deactivated

The Add to Slack button also allows for an optional state parameter that will be returned on completion of the request. The creating and created callbacks include an options hash where this value can be accessed (to check for forgery attacks for instance).

auth = OpenSSL::HMAC.hexdigest("SHA256", "key", "data")

<a href="https://slack.com/oauth/authorize?scope=bot&client_id=<%= ENV['SLACK_CLIENT_ID'] %>&state=#{auth)"> ... </a>

instance = SlackRubyBotServer::Service.instance
instance.on :creating do |team, error, options|
  raise "Unauthorized response" unless options[:state] == auth
end
Service Timers

You can introduce custom behavior into the service lifecycle on a timer. For example, check whether a team's trial has expired, or periodically cleanup data.

Note that unlike callbacks, timers are global for the entire service.

instance = SlackRubyBotServer::Service.instance

instance.every :hour do
  Team.each do |team|
    begin
      # do something with every team once an hour
    rescue StandardError
    end
  end
end

instance.every :minute do
  # called every minute
end

instance.every :second do
  # called every second
end

instance.every 30 do
  # called every 30 seconds
end
Extensions

A number of extensions use service manager callbacks and service timers to implement useful functionality.

Server Class

You can override the server class to handle additional events, and configure the service to use it.

class MyServer < SlackRubyBotServer::Server
  on :hello do |client, data|
    # connected to Slack
  end

  on :channel_joined do |client, data|
    # the bot joined a channel in data.channel['id']
  end
end

SlackRubyBotServer.configure do |config|
  config.server_class = MyServer
end

Service Class

You can override the service class to handle additional methods.

class MyService < SlackRubyBotServer::Service
  def url
    'https://www.example.com'
  end
end

SlackRubyBotServer.configure do |config|
  config.service_class = MyService
end

SlackRubyBotServer::Service.instance # MyService
SlackRubyBotServer::Service.instance.url # https://www.example.com

HTML Templates

This library provides a default HTML template and JS scripts that implement the "Add to Slack" button workflow. Customize your pages by adding a public directory in your application and starting with a index.html.erb template. The application's views and public folders are loaded by default.

You can add to or override template paths as follows.

SlackRubyBotServer.configure do |config|
  config.view_paths << File.expand_path(File.join(__dir__, 'public'))
end

Access Tokens

By default the implementation of Team stores a bot_access_token as token that grants a certain amount of privileges to the bot user as described in Slack OAuth Docs along with activated_user_access_token that represents the token of the installing user. You may not want a bot user at all, or may require different auth scopes, such as users.profile:read to access user profile information via Slack::Web::Client#users_profile_get. To change required scopes make the following changes.

1) Configure your app to require additional scopes in Slack API under OAuth, Permissions 2) Change the Add to Slack buttons to require the additional scope, eg. https://slack.com/oauth/authorize?scope=bot,users.profile:read&client_id=... 3) The access token with the requested scopes will be stored as activated_user_access_token.

You can see a sample implementation in slack-sup#3a497b.

Example Bots Using Slack Ruby Bot Server

Copyright Daniel Doubrovkine and Contributors, 2015-2020

MIT License