In a recent client project, I've been re-building a Rails 2.x eCommerce site in Rails 4.2, and when this is launched on production, I wanted to be able to drop tarballs of various tables straight into the git repo and have a migration unpack those tarballs and import them into the DB; the drop-table clauses in the SQL will ensure existing tables will be selectively replaced upon import.
The entire unpacking of the compressed tarball is done in memory, and the script looks for the file in the bootstrap folder in the app root. The database.yml file is used to fetch login credentials, and that's how the extracted SQL file is imported into MySQL.
require 'rubygems'
require 'rubygems/package'
require 'zlib'
require 'fileutils'
module Util
module Tar
# Creates a tar file in memory recursively
# from the given path.
#
# Returns a StringIO whose underlying String
# is the contents of the tar file.
def tar(path)
tarfile = StringIO.new("")
Gem::Package::TarWriter.new(tarfile) do |tar|
Dir[File.join(path, "**/*")].each do |file|
mode = File.stat(file).mode
relative_file = file.sub /^#{Regexp::escape path}\/?/, ''
if File.directory?(file)
tar.mkdir relative_file, mode
else
tar.add_file relative_file, mode do |tf|
File.open(file, "rb") { |f| tf.write f.read }
end
end
end
end
tarfile.rewind
tarfile
end
# gzips the underlying string in the given StringIO,
# returning a new StringIO representing the
# compressed file.
def gzip(tarfile)
gz = StringIO.new("")
z = Zlib::GzipWriter.new(gz)
z.write tarfile.string
z.close # this is necessary!
# z was closed to write the gzip footer, so
# now we need a new StringIO
StringIO.new gz.string
end
# un-gzips the given IO, returning the
# decompressed version as a StringIO
def ungzip(tarfile)
z = Zlib::GzipReader.new(tarfile)
unzipped = StringIO.new(z.read)
z.close
unzipped
end
# untars the given IO into the specified
# directory
def untar(io, destination)
Gem::Package::TarReader.new io do |tar|
tar.each do |tarfile|
destination_file = File.join destination, tarfile.full_name
if tarfile.directory?
FileUtils.mkdir_p destination_file
else
destination_directory = File.dirname(destination_file)
FileUtils.mkdir_p destination_directory unless File.directory?(destination_directory)
File.open destination_file, "wb" do |f|
f.print tarfile.read
end
end
end
end
end
end
end
class ImportAccountsFromSqlFile < ActiveRecord::Migration
include Util::Tar
def change
require 'fileutils'
require 'tmpdir'
archive_filename = 'accounts'
data_dir = Dir.mktmpdir
at_exit {FileUtils.rm_rf(data_dir)}
data_path = File.expand_path("#{archive_filename}.sql", data_dir)
db_yaml = YAML.load_file(Rails.root.join('config','database.yml'))
db_u = db_yaml[Rails.env]['username']
db_p = db_yaml[Rails.env]['password']
db = db_yaml[Rails.env]['database']
db_host = db_yaml[Rails.env]['host']
`cp #{Rails.root.join('bootstrap', "#{archive_filename}.tar.gz")} #{data_dir}`
tarball = data_path.gsub('.sql', '.tar.gz')
io = ungzip(File.open(tarball, 'rb'))
untar(io, data_dir)
options = "-o "
options << "-h#{db_host} " if db_host && db_host.present?
options << "-u#{db_u} -p#{db_p}"
puts "---> SQL PATH: #{data_path}"
`mysql #{options} #{db} < #{data_path}`
ActiveRecord::Base.connection.execute('UPDATE accounts SET user_id = NULL')
end
end