Transfer everything from one postgres instance to another

pg_transfer.rb

#!/usr/bin/env ruby

require 'uri'
require 'delegate'

class PG < SimpleDelegator
  FLAGS = ['--verbose', '--clean', '--no-owner', '--no-acl', '-j', '4']

  def initialize(url)
    super URI.parse(url)
  end

  def db
    path[1..-1]
  end

  def port
    super.to_s if super
  end

  def to_env
    {
      'PGHOST'     => host,
      'PGPORT'     => port,
      'PGUSER'     => user,
      'PGPASSWORD' => password
    }
  end

  def dump(to:)
    run 'pg_dump', '-Fd', db, *FLAGS, '-f', to
  end

  def restore(from:)
    run 'pg_restore', '--create', *FLAGS, '-d', db, from
  end

  def run(*args)
    opts = args.last.respond_to?(:keys) ? args.pop : {}

    unless system(to_env, *args, opts)
      abort "Command failed: #{args.join(' ')}"
    end
  end
end

if ARGV.length != 2
  example = 'postgres://user:pass@host:port/db'
  abort "Usage: #{$0} #{example} #{example}"
end

source, destination = ARGV.map { |v| PG.new(v) }

source.dump(to: 'dump')
destination.restore(from: 'dump')