improved heroku deploy rake task

deploy.rake

#Deploy and rollback on Heroku in staging, production, dev and test environments

require 'tempfile'

# for capturing error in 'git push'
def capture_stderr
  stderr = $stderr.dup
  Tempfile.open 'stderr-redirect' do |temp|
    $stderr.reopen temp.path, 'w+'
    yield if block_given?
    $stderr.reopen stderr
    temp.read
  end
end

%w[dev test production staging].each do |app|
  desc "Deploy to #{app}"
  task "deploy:#{app}" => %W[deploy:set_#{app}_app deploy:push deploy:restart deploy:tag]

  desc "Deploy #{app} with migrations"
  task "deploy:#{app}:migrations" => %W[deploy:set_#{app}_app deploy:push deploy:off deploy:migrate deploy:restart deploy:on deploy:tag]

  desc "Rollback #{app}"
  task "#{app}:rollback" => ["set_#{app}_app".to_sym, :off, :push_previous, :restart, :on]

  %w[logs config ps releases console scheduler init_db].each do |app_task|
    desc "#{app} #{app_task}"
    task "app:#{app}:#{app_task}" => ["deploy:set_#{app}_app", "app:#{app_task}"]
  end
end


namespace :deploy do

  PRODUCTION_APP = 'YOUR_PRODUCTION_APP_NAME_ON_HEROKU'
  STAGING_APP = 'YOUR_STAGING_APP_NAME_ON_HEROKU'
  TEST_APP = 'YOUR_TEST_APP_NAME_ON_HEROKU'
  DEV_APP = 'YOUR_DEVELOPMENT_APP_NAME_ON_HEROKU'

  # metaprogramming
  %w[dev test production staging].each do |app|
    task "set_#{app}_app" do
      # a trick to read a constant
      const_value = Object.const_get(app.upcase+'_APP')
      if !const_value || const_value.empty? || const_value == "YOUR_#{app.upcase}_APP_NAME_ON_HEROKU"
        raise "APP #{app.upcase} IS NOT SET"
      end
      APP = const_value
    end
  end

  task :push do
    git_status = `git status -v`
    abort("local branch is out of sync with github origin. please push there first") if git_status.match(/\*[^\]]+?\[ahead|behind/s) != nil
    current_branch = `git rev-parse --abbrev-ref HEAD`.chomp
    current_branch += ":master" if current_branch != "master"
    puts "Deploying #{current_branch} to #{APP} ..."
    #captured_content = capture_stderr do
    puts `git push -f git@heroku.com:#{APP}.git #{current_branch}`
    #end
    # display captured content
    #puts captured_content.to_s
    # stop furthe task chain in case of error (e.g. app name is invalid)
    #raise "EXIT" if captured_content.to_s.match(/fatal/)
  end

  task :restart do
    puts 'Restarting app servers ...'
    Bundler.with_clean_env do
      puts `heroku restart --app #{APP}`
    end
  end

  task :tag do
    release_name = "#{APP}-release-#{Time.now.utc.strftime("%Y%m%d-%H%M%S")}"
    puts "Tagging release as '#{release_name}'"
    puts `git tag -a #{release_name} -m 'Tagged release'`
    puts `git push --tags git@heroku.com:#{APP}.git`
    puts `git push --tags origin`
  end

  task :migrate do
    puts 'Running database migrations ...'
    Bundler.with_clean_env do
      puts `heroku run rake db:migrate --app #{APP}`
    end
  end

  task :off do
    puts 'Putting the app into maintenance mode ...'
    Bundler.with_clean_env do
      puts `heroku maintenance:on --app #{APP}`
    end
  end

  task :on do
    puts 'Taking the app out of maintenance mode ...'
    Bundler.with_clean_env do
      puts `heroku maintenance:off --app #{APP}`
    end
  end

  task :push_previous do
    prefix = "#{APP}-release-"
    releases = `git tag`.split("\n").select { |t| t[0..prefix.length-1] == prefix }.sort
    current_release = releases.last
    previous_release = releases[-2] if releases.length >= 2
    if previous_release
      puts "Rolling back to '#{previous_release}' ..."

      puts "Checking out '#{previous_release}' in a new branch on local git repo ..."
      puts `git checkout #{previous_release}`
      puts `git checkout -b #{previous_release}`

      puts "Removing tagged version '#{previous_release}' (now transformed in branch) ..."
      puts `git tag -d #{previous_release}`
      puts `git push git@heroku.com:#{APP}.git :refs/tags/#{previous_release}`

      puts "Pushing '#{previous_release}' to Heroku master ..."
      puts `git push git@heroku.com:#{APP}.git +#{previous_release}:master --force`

      puts "Deleting rollbacked release '#{current_release}' ..."
      puts `git tag -d #{current_release}`
      puts `git push git@heroku.com:#{APP}.git :refs/tags/#{current_release}`

      puts "Retagging release '#{previous_release}' in case to repeat this process (other rollbacks)..."
      puts `git tag -a #{previous_release} -m 'Tagged release'`
      puts `git push --tags git@heroku.com:#{APP}.git`

      puts "Turning local repo checked out on master ..."
      puts `git checkout master`
      puts 'All done!'
    else
      puts "No release tags found - can't roll back!"
      puts releases
    end
  end
end

namespace :app do
  task :logs do
    puts "tailing logs..."
    Bundler.clean_exec "heroku logs --tail --app #{APP}"
  end

  task :config do
    puts "config..."
    Bundler.with_clean_env do
      puts `heroku config --app #{APP}`
    end
  end

  task :console do
    puts "console..."
    Bundler.with_clean_env do
      sh "heroku run rails c --app #{APP}"
    end
  end

  task :scheduler do
    puts "scheduler..."
    Bundler.with_clean_env do
      sh "heroku addons:open scheduler --app #{APP}"
    end
  end

  task :ps do
    puts "running processes..."
    Bundler.with_clean_env do
      puts `heroku ps --app #{APP}`
    end
  end

  task :releases do
    puts "releases..."
    Bundler.with_clean_env do
      puts `heroku releases --app #{APP}`
    end
  end

  task :init_db do
    puts "init database"
    Bundler.with_clean_env do
      puts `heroku maintenance:on --app #{APP}`
      puts `heroku run rake db:schema:load --app #{APP}`
      puts `heroku run rake db:migrate --app #{APP}`
      puts `heroku run rake db:seed --app #{APP}`
      puts `heroku maintenance:off --app #{APP}`
    end
  end
end

added environments QA and DEV

use pty to monitor git push and stop further tasks in case of error (it helps to avoid tagging in case of error during deployment)