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Slack Ruby Bot Server

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

Table of Contents

What is this?

A library that contains a web server and a RESTful Grape API serving a Slack bot to multiple teams. Use in conjunction with slack-ruby-bot-server-events to build a complete Slack bot service, or slack-ruby-bot-server-rtm to build a (legacy) Classic RealTime Slack bot. Your customers can use a Slack button to install the bot.

Stable Release

You're reading the documentation for the next release of slack-ruby-bot-server. Please see the documentation for the last stable release, v2.1.0 unless you're integrating with HEAD. See UPGRADING when upgrading from an older version. See MIGRATING for help with migrating Legacy Slack Apps to Granular Scopes.

Make Your Own

This library alone will only register a new bot, but will not include any bot functionality. To make something useful, we recommend you get started from either slack-ruby-bot-server-events-app-mentions-sample (handles a single kind of event), or slack-ruby-bot-server-events-sample (handles all kinds of events) to bootstrap your project.

Usage

Storage

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'

ActiveRecord

Use ActiveRecord with, for example, PostgreSQL via pg. Add the activerecord, pg, otr-activerecord and pagy_cursor gems to your Gemfile. Currently supports ActiveRecord/Rails major versions 6.0, 6.1 and 7.0.

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

Configure the database connection in config/postgresql.yml.

default: &default
  adapter: postgresql
  pool: 10
  timeout: 5000
  encoding: unicode

development:
  <<: *default
  database: bot_development

test:
  <<: *default
  database: bot_test

production:
  <<: *default
  database: bot

Establish a connection in your startup code.

ActiveRecord::Base.establish_connection(
  YAML.safe_load(
    ERB.new(
      File.read('config/postgresql.yml')
    ).result, [], [], true
  )[ENV['RACK_ENV']]
)

OAuth Version and Scopes

Configure your app's OAuth version and scopes as needed by your application.

SlackRubyBotServer.configure do |config|
  config.oauth_version = :v2
  config.oauth_scope = ['channels:read', 'chat:write']
end

The "Add to Slack" button uses the standard OAuth code grant flow as described in the Slack docs. 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 persists the bot token each time a Slack client is instantiated for the specific team.

Slack App

Create a new Slack App here.

Follow Slack's instructions, note the app client ID and secret, give the bot a default name, etc.

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.

$ foreman start
07:44:47 web.1  | started with pid 59258
07:44:50 web.1  | * Listening on tcp://0.0.0.0:5000

Set the redirect URL in "OAuth & Permissions" be the location of your app. Since you cannot receive notifications on localhost from Slack use a public tunneling service such as ngrok to expose local port 9292 for testing.

$ ngrok http 5000
Forwarding https://ddfd97f80615.ngrok.io -> http://localhost:5000

Navigate to either localhost:9292 or the ngrok URL above. You should see an "Add to Slack" button. Use it to install the app into your own Slack team.

API

This library implements an app, SlackRubyBotServer::App and a service manager, SlackRubyBotServer::Service. 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.

callbackdescription
erroran error has occurred
creatinga new team is being registered
createda new team has been registered
bootingthe service is starting and is connecting a team to Slack
bootedthe service is starting and has connected a team to Slack
stoppingthe service is about to disconnect a team from Slack
stoppedthe service has disconnected a team from Slack
startingthe service is (re)connecting a team to Slack
startedthe service has (re)connected a team to Slack
deactivatinga team is being deactivated
deactivateda 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="<%= SlackRubyBotServer::Config.oauth_authorize_url %>?scope=<%= SlackRubyBotServer::Config.oauth_scope_s %>&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 clean-up data. Timers can run once on start (once_and_every) and start running after a certain period (every).

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.once_and_every :minute do
  # called once on start, then every minute
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

Note that, unlike callbacks, timers are global for the entire service. Timers are independent, and a failing timer will not terminate other timers.

Extensions

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

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 the value of the token with all the requested OAuth scopes in both token and activated_user_access_token (for backwards compatibility), along with oauth_version and oauth_scope. If a legacy Slack bot integration bot_access_token is present, it is stored as token, and activated_user_access_token is the token that has all the requested OAuth scopes.

Sample Bots Using Slack Ruby Bot Server

Slack Bots with Granular Permissions

Legacy Slack Bots

Copyright & License

Copyright Daniel Doubrovkine and Contributors, 2015-2020

MIT License