Restore Object Pools when restoring an object pool

Pool repositories are persisted in the database, and when the DB is
restored, the data need to be restored on disk. This is done by
resetting the state machine and rescheduling the object pool creation.

This is not an exact replica of the state like at the time of the
creation of the backup. However, the data is consistent again.

Dumping isn't required as internally GitLab uses git bundles which
bundle all refs and include all objects in the bundle that they require,
reduplicating as more repositories get backed up. This does require more
data to be stored.

Fixes https://gitlab.com/gitlab-org/gitaly/issues/1355

app/models/pool_repository.rb

@@ -84,6 +84,10 @@ class PoolRepository < ActiveRecord::Base
       source_project.repository.raw)
   end
 
+  def inspect
+    "#<#{self.class.name} id:#{id} state:#{state} disk_path:#{disk_path} source_project: #{source_project.full_path}>"
+  end
+
   private
 
   def correct_disk_path

changelogs/unreleased/zj-backup-restore-object-pools.yml

+---
+title: Restore Object Pools when restoring an object pool
+merge_request: 23682
+author:
+type: added

doc/raketasks/backup_restore.md

@@ -657,6 +657,7 @@ Restoring database tables:
 - Loading fixture wikis...[SKIPPING]
 Restoring repositories:
 - Restoring repository abcd... [DONE]
+- Object pool 1 ...
 Deleting tmp directories...[DONE]
 ```
 

lib/backup/repository.rb

@@ -4,6 +4,7 @@ require 'yaml'
 
 module Backup
   class Repository
+    include Gitlab::ShellAdapter
     attr_reader :progress
 
     def initialize(progress)
@@ -75,7 +76,6 @@ module Backup
 
     def restore
       prepare_directories
-      gitlab_shell = Gitlab::Shell.new
 
       Project.find_each(batch_size: 1000) do |project|
         progress.print " * #{project.full_path} ... "
@@ -118,6 +118,8 @@ module Backup
           end
         end
       end
+
+      restore_object_pools
     end
 
     protected
@@ -159,5 +161,17 @@ module Backup
     def display_repo_path(project)
       project.hashed_storage?(:repository) ? "#{project.full_path} (#{project.disk_path})" : project.full_path
     end
+
+    def restore_object_pools
+      PoolRepository.includes(:source_project).find_each do |pool|
+        progress.puts " - Object pool #{pool.disk_path}..."
+
+        pool.source_project ||= pool.member_projects.first.root_of_fork_network
+        pool.state = 'none'
+        pool.save
+
+        pool.schedule
+      end
+    end
   end
 end

spec/lib/backup/repository_spec.rb

@@ -67,6 +67,19 @@ describe Backup::Repository do
         end
       end
     end
+
+    context 'restoring object pools' do
+      it 'schedules restoring of the pool' do
+        pool_repository = create(:pool_repository, :failed)
+        pool_repository.delete_object_pool
+
+        subject.restore
+
+        pool_repository.reload
+        expect(pool_repository).not_to be_failed
+        expect(pool_repository.object_pool.exists?).to be(true)
+      end
+    end
   end
 
   describe '#prepare_directories', :seed_helper do

spec/tasks/gitlab/backup_rake_spec.rb

@@ -74,6 +74,7 @@ describe 'gitlab:app namespace rake task' do
       it 'invokes restoration on match' do
         allow(YAML).to receive(:load_file)
           .and_return({ gitlab_version: gitlab_version })
+
         expect(Rake::Task['gitlab:db:drop_tables']).to receive(:invoke)
         expect(Rake::Task['gitlab:backup:db:restore']).to receive(:invoke)
         expect(Rake::Task['gitlab:backup:repo:restore']).to receive(:invoke)