ActiveRecord criar, descartar e migrações sem Rails

Aqui está uma tarefa de criação, eliminação e migração do Active Record (> 5) sem trilhos baseada no artigo de Wes Bailey .

criado por: charly-palencia & Erlinis
Detalhes:
* Somente banco de dados PostgreSQL

database_connection.rb

require 'active_record'
require 'erb'

module DatabaseConnection
  def self.connect!(env)
    #Ref https://github.com/puma/puma#clustered-mode
    ActiveSupport.on_load(:active_record) do
      ::ActiveRecord::Base.connection_pool.disconnect! if ::ActiveRecord::Base.connected?
      ::ActiveRecord::Base.configurations = YAML.load(ERB.new(File.read("db/config.yml")).result) || {}
      config = ::ActiveRecord::Base.configurations[env.to_s]
      ::ActiveRecord::Base.establish_connection(config)
    end
  end
end

tarefas / banco de dados.rb

require 'yaml'
require 'config/database_connection'
require 'active_record'

namespace :db do

 task :environment do
   path =  File.join(File.dirname(__FILE__), '../db/migrate')
   migrations_paths = [path]
   DATABASE_ENV = ENV['RACK_ENV'] || 'development'
   MIGRATIONS_DIR = ENV['MIGRATIONS_DIR'] || migrations_paths
 end

 task :configuration => :environment do
   @config = YAML.load(ERB.new(File.read("db/config.yml")).result)[DATABASE_ENV]
 end

 task :configure_connection => :configuration do
   DatabaseConnection.connect!(DATABASE_ENV)
   ActiveRecord::Base.logger = Logger.new STDOUT if @config['logger']
 end

 desc 'Create the database from db/config.yml for the current DATABASE_ENV'
 task :create => :configure_connection do
   database = ActiveRecord::Tasks::PostgreSQLDatabaseTasks.new(@config)
   database.create
   puts "Database created"
 end

 desc 'Drops the database for the current DATABASE_ENV'
 task :drop => :configure_connection do
   database = ActiveRecord::Tasks::PostgreSQLDatabaseTasks.new(@config)
   database.drop
   puts "Database dropped"
 end

 desc 'Migrate the database (options: VERSION=x, VERBOSE=false).'
 task :migrate => :configure_connection do
   begin
     verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] == "true" : true
     version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
     scope   = ENV['SCOPE']
     verbose_was, ActiveRecord::Migration.verbose = ActiveRecord::Migration.verbose, verbose
     ActiveRecord::Migrator.migrate(MIGRATIONS_DIR, version) do |migration|
    scope.blank? || scope == migration.scope
     end
     ActiveRecord::Base.clear_cache!
   ensure
     ActiveRecord::Migration.verbose = verbose_was
   end
 end

 desc 'Rolls the schema back to the previous version (specify steps w/ STEP=n).'
 task :rollback => :configure_connection do
   step = ENV['STEP'] ? ENV['STEP'].to_i : 1
   ActiveRecord::Migrator.rollback(MIGRATIONS_DIR, step)
 end