slack + capistrano

slack.rake

# lib/capistrano/tasks/slack.rake

# install slack-notifier gem
# include this file into your lib/capistrano/tasks/ folder
# add this line to the end of your Capfile: 
#    Dir.glob('lib/capistrano/tasks/*.rake').each { |r| import r }
# deploy with: 
#    MSG='fixing that payment bug...' cap staging deploy 

class SlackNotifierWrapper
  
  require 'slack-notifier'

  def token
    'XXXXXXXXXXX'
  end

  def team
    "your-subdomain-on-slack"
  end

  def channel
    '#deployments'
  end

  def app
    "my-awesome-app"
  end

  def deployer
    ENV['GIT_AUTHOR_NAME'] || `git config user.name`.chomp
  end

  def reason
    raise "provice a reason with MSG=... !" unless ENV['MSG']
    ENV['MSG']
  end

  def notify(msg)
    notifier.ping(msg, icon_emoji: ":rocket:")
  end

  def notifier
    @notifier ||= ::Slack::Notifier.new(team, token, channel: channel, username: 'capistrano')
  end
end


namespace :slack do
  def wrapper
    @wrapper ||= SlackNotifierWrapper.new
  end

  def msg_prefix
    deployer   = wrapper.deployer
    app        = wrapper.app
    branch     = fetch(:branch, nil)
    stage      = fetch(:stage, 'production')
    app_string = branch ? "#{app}'s #{branch}" : app


    "#{deployer} / #{app_string} / #{stage}"
  end

  task :starting do
    msg = "#{msg_prefix} - started - #{wrapper.reason}"

    wrapper.notify(msg)
    set(:start_time, Time.now)
  end

  task :finished do
    begin
      start_time = fetch(:start_time)
      elapsed    = Time.now.to_i - start_time.to_i
      msg        = "#{msg_prefix} - finished - #{elapsed} seconds."
      wrapper.notify(msg)
    end
  end

  before 'deploy', 'slack:starting'
  after 'deploy',  'slack:finished'
end