Custom Heroku deploy Strategy. Migrates the database only when needed. Needs heroku_san to work Needs to have all stages added as git remote! (via rake all heroku:remotes)

migrate_when_needed_strategy.rb

# Custom Heroku deploy Strategy
# Needs to have all stages added as git remote! (via rake all heroku:remotes)
if defined?(HerokuSan)
  class MigrateWhenNeededStrategy < HerokuSan::Deploy::Base
    def deploy
      puts "[#{@stage.name}] Fetching current state."
      `git fetch #{@stage.name}`
      puts "[#{@stage.name}] Deploying..."
      super
      previous_sha_commit = `git rev-parse HEAD`.strip
      puts "[#{@stage.name}] Deployed these changed:"
      puts `git log --pretty=format:"* %s" #{@stage.name}/master..#{previous_sha_commit}`
      puts ""
      puts "[#{@stage.name}] Checking to see if we need to run the migrations."
      file_changes = `git diff --name-only #{previous_sha_commit} #{@stage.name}/master`
      if file_changes.index("db/migrate")
        puts "[#{@stage.name}] Running migrations, as there are new ones added."
        @stage.run('rake db:migrate')
        puts "[#{@stage.name}] Restarting..."
        @stage.restart
      end
      if file_changes.index("db/seeds.rb")
        puts "[#{@stage.name}] It looks like you adjusted or created the seeds.rb file."
        print "[#{@stage.name}] Do you want to run the rake db:seed command now? (yes/no)"
        response = gets.chomp
        if response.downcase == 'yes'
          @stage.run('rake db:seed')
        end
      end
    end
  end

  HerokuSan.project = HerokuSan::Project.new(Rails.root.join("config","heroku.yml"), :deploy => MigrateWhenNeededStrategy)
end