Move the `uploads/system` folder to `uploads/-/system`

Without downtime, so we need the symlinks

db/migrate/20170717074009_move_system_upload_folder.rb

+class MoveSystemUploadFolder < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+  disable_ddl_transaction!
+
+  DOWNTIME = false
+
+  def up
+    unless file_storage?
+      say 'Using object storage, no need to move.'
+      return
+    end
+
+    unless File.directory?(old_directory)
+      say "#{old_directory} doesn't exist, no need to move it."
+      return
+    end
+
+    FileUtils.mkdir_p(File.join(base_directory, '-'))
+
+    say "Moving #{old_directory} -> #{new_directory}"
+    FileUtils.mv(old_directory, new_directory)
+    FileUtils.ln_s(new_directory, old_directory)
+  end
+
+  def down
+    unless file_storage?
+      say 'Using object storage, no need to move.'
+      return
+    end
+
+    unless File.directory?(new_directory)
+      say "#{new_directory} doesn't exist, no need to move it."
+      return
+    end
+
+    if File.symlink?(old_directory)
+      say "Removing #{old_directory} -> #{new_directory} symlink"
+      FileUtils.rm(old_directory)
+    end
+
+    say "Moving #{new_directory} -> #{old_directory}"
+    FileUtils.mv(new_directory, old_directory)
+  end
+
+  def new_directory
+    File.join(base_directory, '-', 'system')
+  end
+
+  def old_directory
+    File.join(base_directory, 'system')
+  end
+
+  def base_directory
+    File.join(Rails.root, 'public', 'uploads')
+  end
+
+  def file_storage?
+    CarrierWave::Uploader::Base.storage == CarrierWave::Storage::File
+  end
+end

db/post_migrate/20170717111152_cleanup_move_system_upload_folder_symlink.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class CleanupMoveSystemUploadFolderSymlink < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    if File.symlink?(old_directory)
+      say "Removing #{old_directory} -> #{new_directory} symlink"
+      FileUtils.rm(old_directory)
+    else
+      say "Symlink #{old_directory} non existant, nothing to do."
+    end
+  end
+
+  def down
+    if File.directory?(new_directory)
+      say "Symlinking #{old_directory} -> #{new_directory}"
+      FileUtils.ln_s(new_directory, old_directory)
+    else
+      say "#{new_directory} doesn't exist, skipping."
+    end
+  end
+
+  def new_directory
+    File.join(base_directory, '-', 'system')
+  end
+
+  def old_directory
+    File.join(base_directory, 'system')
+  end
+
+  def base_directory
+    File.join(Rails.root, 'public', 'uploads')
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170713104829) do
+ActiveRecord::Schema.define(version: 20170717111152) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"

spec/migrations/cleanup_move_system_upload_folder_symlink_spec.rb

+require 'spec_helper'
+require Rails.root.join("db", "post_migrate", "20170717111152_cleanup_move_system_upload_folder_symlink.rb")
+
+describe CleanupMoveSystemUploadFolderSymlink do
+  let(:migration) { described_class.new }
+  let(:test_base) { File.join(Rails.root, 'tmp', 'tests', 'move-system-upload-folder') }
+  let(:test_folder) { File.join(test_base, '-', 'system') }
+
+  before do
+    allow(migration).to receive(:base_directory).and_return(test_base)
+    FileUtils.rm_rf(test_base)
+    FileUtils.mkdir_p(test_folder)
+    allow(migration).to receive(:say)
+  end
+
+  describe '#up' do
+    before do
+      FileUtils.ln_s(test_folder, File.join(test_base, 'system'))
+    end
+
+    it 'removes the symlink' do
+      migration.up
+
+      expect(File.exist?(File.join(test_base, 'system'))).to be_falsey
+    end
+  end
+
+  describe '#down' do
+    it 'creates the symlink' do
+      migration.down
+
+      expect(File.symlink?(File.join(test_base, 'system'))).to be_truthy
+    end
+  end
+end

spec/migrations/move_system_upload_folder_spec.rb

+require 'spec_helper'
+require Rails.root.join("db", "migrate", "20170717074009_move_system_upload_folder.rb")
+
+describe MoveSystemUploadFolder do
+  let(:migration) { described_class.new }
+  let(:test_base) { File.join(Rails.root, 'tmp', 'tests', 'move-system-upload-folder') }
+
+  before do
+    allow(migration).to receive(:base_directory).and_return(test_base)
+    FileUtils.rm_rf(test_base)
+    FileUtils.mkdir_p(test_base)
+    allow(migration).to receive(:say)
+  end
+
+  describe '#up' do
+    let(:test_folder) { File.join(test_base, 'system') }
+    let(:test_file) { File.join(test_folder, 'file') }
+
+    before do
+      FileUtils.mkdir_p(test_folder)
+      FileUtils.touch(test_file)
+    end
+
+    it 'moves the related folder' do
+      migration.up
+
+      expect(File.exist?(File.join(test_base, '-', 'system', 'file'))).to be_truthy
+    end
+
+    it 'creates a symlink linking making the new folder available on the old path' do
+      migration.up
+
+      expect(File.symlink?(File.join(test_base, 'system'))).to be_truthy
+      expect(File.exist?(File.join(test_base, 'system', 'file'))).to be_truthy
+    end
+  end
+
+  describe '#down' do
+    let(:test_folder) { File.join(test_base, '-', 'system') }
+    let(:test_file) { File.join(test_folder, 'file') }
+
+    before do
+      FileUtils.mkdir_p(test_folder)
+      FileUtils.touch(test_file)
+    end
+
+    it 'moves the system folder back to the old location' do
+      migration.down
+
+      expect(File.exist?(File.join(test_base, 'system', 'file'))).to be_truthy
+    end
+
+    it 'removes the symlink if it existed' do
+      FileUtils.ln_s(test_folder, File.join(test_base, 'system'))
+
+      migration.down
+
+      expect(File.directory?(File.join(test_base, 'system'))).to be_truthy
+      expect(File.symlink?(File.join(test_base, 'system'))).to be_falsey
+    end
+  end
+end