Clone task for heroku databases

hdb.rake

# tasks for working with your heroku database
#
# Examples:
#
# Replace development DB with a fresh capture from Heroku
# (removing the oldest one first)
#
# rake hdb:clone # replace development database with a fresh capture of the
# heroku database
#
# choose a different local:
# RAILS_ENV=production rake hdb:clone
#
# choose a different remote:
# HEROKU_APP=the-production-app-name rake hdb:clone

namespace :hdb do
  def hdbconfig
    env = ENV.fetch 'RAILS_ENV', 'development'
    @hdbconfig ||= ActiveRecord::Base.configurations[env]
  end

  task(ensure_dropped: 'db:load_config') { drop_database hdbconfig }

  task(create_one: 'db:load_config') { create_database hdbconfig }

  desc "replace the RAILS_ENV database with a fresh capture from HEROKU_APP"
  task clone: [:ensure_dropped, :create_one] do
    env = ENV.fetch 'RAILS_ENV', 'development'
    HerokuDB.capture_and_restore(env)
  end
end

class HerokuDB
  def self.capture_and_restore(env)
    db = new(env)
    db.capture
    db.restore
  end

  attr_reader :environment

  def initialize(env)
    @environment = env
  end

  def capture
    pgbackup 'capture --expire'
  end

  def restore
    print_and_capture %(curl "#{url}" | pg_restore --no-acl --no-owner #{username} -d #{database})
  end

  private

  def url
    pgbackup(:url).chomp
  end

  def username
    if config['username']
      "-U #{config['username']}"
    end
  end

  def database
    config['database']
  end

  def config
    @config ||= ActiveRecord::Base.configurations[environment]
  end

  def pgbackup(task=nil)
    sub_command = task ? "pgbackups:#{task}" : 'pgbackups'
    print_and_capture "heroku #{sub_command} #{heroku_app}"
  end

  def heroku_app
    return @heroku_app if defined?(@heroku_app)
    @heroku_app = determine_heroku_app
  end
  def determine_heroku_app
    if ENV['HEROKU_APP']
      return "--app #{ENV['HEROKU_APP']}"
    end

    remotes = `git remote`.chomp.split("\n")
    remote = %w(heroku production staging heroku-production heroku-staging).detect do |remote|
      remotes.include?(remote)
    end

    "--remote #{remote}" if remote
  end

  def print_and_capture(command)
    puts command
    output = `#{command}`
    exit "non-zero exit status!" if $?.exitstatus != 0
    output
  end
end