1 files changed, 121 insertions, 0 deletions
diff --git a/app/models/concerns/repository_storage_movable.rb b/app/models/concerns/repository_storage_movable.rb
new file mode 100644
index 00000000000..a45b4626628
--- /dev/null
+++ b/app/models/concerns/repository_storage_movable.rb
@@ -0,0 +1,121 @@
+# frozen_string_literal: true
+
+module RepositoryStorageMovable
+  extend ActiveSupport::Concern
+  include AfterCommitQueue
+
+  included do
+    scope :order_created_at_desc, -> { order(created_at: :desc) }
+
+    validates :container, presence: true
+    validates :state, presence: true
+    validates :source_storage_name,
+      on: :create,
+      presence: true,
+      inclusion: { in: ->(_) { Gitlab.config.repositories.storages.keys } }
+    validates :destination_storage_name,
+      on: :create,
+      presence: true,
+      inclusion: { in: ->(_) { Gitlab.config.repositories.storages.keys } }
+    validate :container_repository_writable, on: :create
+
+    default_value_for(:destination_storage_name, allows_nil: false) do
+      pick_repository_storage
+    end
+
+    state_machine initial: :initial do
+      event :schedule do
+        transition initial: :scheduled
+      end
+
+      event :start do
+        transition scheduled: :started
+      end
+
+      event :finish_replication do
+        transition started: :replicated
+      end
+
+      event :finish_cleanup do
+        transition replicated: :finished
+      end
+
+      event :do_fail do
+        transition [:initial, :scheduled, :started] => :failed
+        transition replicated: :cleanup_failed
+      end
+
+      around_transition initial: :scheduled do |storage_move, block|
+        block.call
+
+        begin
+          storage_move.container.set_repository_read_only!(skip_git_transfer_check: true)
+        rescue => err
+          storage_move.add_error(err.message)
+          next false
+        end
+
+        storage_move.run_after_commit do
+          storage_move.schedule_repository_storage_update_worker
+        end
+
+        true
+      end
+
+      before_transition started: :replicated do |storage_move|
+        storage_move.container.set_repository_writable!
+
+        storage_move.update_repository_storage(storage_move.destination_storage_name)
+      end
+
+      before_transition started: :failed do |storage_move|
+        storage_move.container.set_repository_writable!
+      end
+
+      state :initial, value: 1
+      state :scheduled, value: 2
+      state :started, value: 3
+      state :finished, value: 4
+      state :failed, value: 5
+      state :replicated, value: 6
+      state :cleanup_failed, value: 7
+    end
+  end
+
+  class_methods do
+    private
+
+    def pick_repository_storage
+      container_klass = reflect_on_association(:container).class_name.constantize
+
+      container_klass.pick_repository_storage
+    end
+  end
+
+  # Projects, snippets, and group wikis has different db structure. In projects,
+  # we need to update some columns in this step, but we don't with the other resources.
+  #
+  # Therefore, we create this No-op method for snippets and wikis and let project
+  # overwrite it in their implementation.
+  def update_repository_storage(new_storage)
+    # No-op
+  end
+
+  def schedule_repository_storage_update_worker
+    raise NotImplementedError
+  end
+
+  def add_error(message)
+    errors.add(error_key, message)
+  end
+
+  private
+
+  def container_repository_writable
+    add_error(_('is read only')) if container&.repository_read_only?
+  end
+
+  def error_key
+    raise NotImplementedError
+  end
+end