Migration to write fullpath in all repository configs

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16027 it was
added to write `gitlab.fullpath` in the git config of all
repositories. But this only writes them on move or migrate to hashed
storage.

This adds a migration that writes the fullpath to all the
repositories.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/41776

changelogs/unreleased/tc-backfill-full-path-config.yml

@@ -0,0 +1,5 @@
+---
+title: Migration to write fullpath in all repository configs
+merge_request: 22322
+author:
+type: other

db/post_migrate/20181010133639_backfill_store_project_full_path_in_repo.rb

@@ -0,0 +1,136 @@
+# frozen_string_literal: true
+
+class BackfillStoreProjectFullPathInRepo < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  class Repository
+    attr_reader :storage
+
+    def initialize(storage, relative_path)
+      @storage = storage
+      @relative_path = relative_path
+    end
+
+    def gitaly_repository
+      Gitaly::Repository.new(storage_name: @storage, relative_path: @relative_path)
+    end
+  end
+
+  module Storage
+    class HashedProject
+      attr_accessor :project
+
+      ROOT_PATH_PREFIX = '@hashed'.freeze
+
+      def initialize(project)
+        @project = project
+      end
+
+      def disk_path
+        "#{ROOT_PATH_PREFIX}/#{disk_hash[0..1]}/#{disk_hash[2..3]}/#{disk_hash}"
+      end
+
+      def disk_hash
+        @disk_hash ||= Digest::SHA2.hexdigest(project.id.to_s) if project.id
+      end
+    end
+
+    class LegacyProject
+      attr_accessor :project
+
+      def initialize(project)
+        @project = project
+      end
+
+      def disk_path
+        project.full_path
+      end
+    end
+  end
+
+  module Routable
+    extend ActiveSupport::Concern
+
+    def full_path
+      @full_path ||= build_full_path
+    end
+
+    def build_full_path
+      if parent && path
+        parent.full_path + '/' + path
+      else
+        path
+      end
+    end
+  end
+
+  class Namespace < ActiveRecord::Base
+    self.table_name = 'namespaces'
+
+    include Routable
+
+    belongs_to :parent, class_name: "Namespace"
+  end
+
+  class Project < ActiveRecord::Base
+    self.table_name = 'projects'
+
+    include Routable
+    include EachBatch
+
+    FULLPATH_CONFIG_KEY = 'gitlab.fullpath'
+
+    belongs_to :namespace
+    delegate :disk_path, to: :storage
+    alias_method :parent, :namespace
+
+    def add_fullpath_config
+      entries = { FULLPATH_CONFIG_KEY => full_path }
+
+      repository_service.set_config(entries)
+    end
+
+    def remove_fullpath_config
+      repository_service.delete_config([FULLPATH_CONFIG_KEY])
+    end
+
+    def storage
+      @storage ||=
+        if hashed_storage?
+          Storage::HashedProject.new(self)
+        else
+          Storage::LegacyProject.new(self)
+        end
+    end
+
+    def hashed_storage?
+      self.storage_version && self.storage_version >= 1
+    end
+
+    def repository
+      @repository ||= Repository.new(repository_storage, disk_path + '.git')
+    end
+
+    def repository_service
+      @repository_service ||= Gitlab::GitalyClient::RepositoryService.new(repository)
+    end
+  end
+
+  def up
+    Project.each_batch do |batch|
+      batch.each do |project|
+        project.add_fullpath_config
+      end
+    end
+  end
+
+  def down
+    Project.each_batch do |batch|
+      batch.each do |project|
+        project.remove_fullpath_config
+      end
+    end
+  end
+end

spec/migrations/backfill_store_project_full_path_in_repo_spec.rb

@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require Rails.root.join('db', 'post_migrate', '20181010133639_backfill_store_project_full_path_in_repo.rb')
+
+describe BackfillStoreProjectFullPathInRepo, :migration do
+  let(:namespaces) { table(:namespaces) }
+  let(:projects) { table(:projects) }
+  let(:group) { namespaces.create!(name: 'foo', path: 'foo') }
+  let(:subgroup) { namespaces.create!(name: 'bar', path: 'bar', parent_id: group.id) }
+
+  subject(:migration) { described_class.new }
+
+  describe '#up' do
+    shared_examples_for 'writes the full path to git config' do
+      it 'writes the git config' do
+        expect_any_instance_of(Gitlab::GitalyClient::RepositoryService)
+          .to receive(:set_config).with('gitlab.fullpath' => expected_path)
+
+        migration.up
+      end
+
+      context 'legacy storage' do
+        it 'finds the repository at the correct location' do
+          Project.find(project.id).create_repository
+
+          expect { migration.up }.not_to raise_error
+        end
+      end
+
+      context 'hashed storage' do
+        it 'finds the repository at the correct location' do
+          project.update_attribute(:storage_version, 1)
+
+          Project.find(project.id).create_repository
+
+          expect { migration.up }.not_to raise_error
+        end
+      end
+    end
+
+    context 'project in group' do
+      let!(:project) { projects.create!(namespace_id: group.id, name: 'baz', path: 'baz') }
+      let(:expected_path) { 'foo/baz' }
+
+      it_behaves_like 'writes the full path to git config'
+    end
+
+    context 'project in subgroup' do
+      let!(:project) { projects.create!(namespace_id: subgroup.id, name: 'baz', path: 'baz') }
+      let(:expected_path) { 'foo/bar/baz' }
+
+      it_behaves_like 'writes the full path to git config'
+    end
+  end
+
+  describe '#down' do
+    context 'project in group' do
+      let!(:project) { projects.create!(namespace_id: group.id, name: 'baz', path: 'baz') }
+
+      it 'deletes the gitlab full config value' do
+        expect_any_instance_of(Gitlab::GitalyClient::RepositoryService)
+          .to receive(:delete_config).with(['gitlab.fullpath'])
+
+        migration.down
+      end
+    end
+  end
+end