Capistrano 2 + Slack

deploy.rb

set :slack_webhook_url, "https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXX/XXXXXXXXXXX"

namespace :slack do
  task :deploy_started do
    username = ENV['USER']

    on_rollback do
      slack(
        color: "danger",
        message: "*#{username}* cancelled deployment of *#{application}* to *#{rails_env}*"
      )
    end

    slack(
      color: "#E8E9EA",
      message: "*#{username}* is deploying *#{application}* to *#{rails_env}*"
    )
  end

  task :deploy_finished do
    username = ENV['USER']
    slack(
      color: "good",
      message: "*#{username}* finished deploying *#{application}* to *#{rails_env}*"
    )
  end

  def slack(color: "good", message: nil)
    require 'httpclient'
    require 'json'
    client = HTTPClient.new
    # client.debug_dev = $stderr
    payload = {
      :attachments => [{
        :color => color,
        :fallback => message.gsub(/\*/, ''),
        :text => message,
        :mrkdwn_in => ["text"]
      }]
    }
    res = client.post fetch(:slack_webhook_url), JSON.generate(payload)
  end
end