Migrate a small database from one RDS instance to another

rds-migrator.rb

require 'fileutils'

start_time = Time.now

SOURCE_DATABASE = {
  :name => '...',
  :user => '...',
  :password => '...',
  :host => '...'
}

TARGET_DATABASE = {
  :name => '...',
  :user => '...',
  :password => '...',
  :host => '...'
}

DUMP_DIRECTORY = '/mnt/migrator'

def benchmark(label = nil)
  puts label unless label.nil?
  before = Time.now
  yield
  after = Time.now
  puts "Took %.3fs" % (after - before)
end

def host_user_password(database)
  "--host='#{database[:host]}' --user='#{database[:user]}' --password='#{database[:password]}'"
end

def dump_database_structure(database)
  dump_file = "#{DUMP_DIRECTORY}/#{database[:name]}_structure.sql"
  FileUtils.mkdir_p(DUMP_DIRECTORY, :mode => 0777)

  benchmark("Dumping structure of #{database[:name]} to #{dump_file}") do
    system "mysqldump --verbose --net_buffer_length=4096 --triggers --compress --no-data #{host_user_password(database)} #{database[:name]} > #{dump_file}"
  end
end

def dump_database_data(database)
  dump_file = "#{DUMP_DIRECTORY}/#{database[:name]}_data.sql"

  benchmark("Dumping #{database[:name]} to #{dump_file}") do
    system "mysqldump --verbose --net_buffer_length=4096 --order-by-primary --compress --single-transaction --no-create-info #{host_user_password(database)} #{database[:name]} > #{dump_file}"
  end
end

def import_database_structure(source, target)
  dump_file = "#{DUMP_DIRECTORY}/#{source[:name]}_structure.sql"

  benchmark("Importing structure of #{source[:name]} from #{dump_file}") do
    system "mysql #{host_user_password(target)} #{target[:name]} < #{dump_file}"
  end
end

def import_database_data(source, target)
  dump_file = "#{DUMP_DIRECTORY}/#{source[:name]}_data.sql"

  benchmark("Importing tables from #{dump_file}") do
    system "mysql #{host_user_password(target)} #{target[:name]} < #{dump_file}"
  end
end

if ARGV.include?('--dump')
  # Run the dumps
  dump_database_structure(SOURCE_DATABASE)
  dump_database_data(SOURCE_DATABASE)
elsif ARGV.include?('--import')
  # Run the imports
  import_database_structure(SOURCE_DATABASE, TARGET_DATABASE)
  import_database_data(SOURCE_DATABASE, TARGET_DATABASE)
else
  # Run it all
  dump_database_structure(SOURCE_DATABASE)
  dump_database_data(SOURCE_DATABASE)
  import_database_structure(SOURCE_DATABASE, TARGET_DATABASE)
  import_database_data(SOURCE_DATABASE, TARGET_DATABASE)
end

puts "Script ran for: %.3fs" % (Time.now - start_time)