Geo: Migrate wikis replication/verification to use SSF

Summary

With the Geo Self-Service Framework implemented, we want to move replication of existing data types to use the SSF. This will improve maintainability and also make it easier to add verification. We can use the example of LFS files migration to SSF in &3113 (closed)

Replicate Project Wiki Repositories - Repository

This issue is for implementing Geo replication and verification of Project Wiki Repositories.

For more background, see Geo self-service framework.

In order to implement and test this feature, you need to first set up Geo locally.

There are three main sections below. It is a good idea to structure your merge requests this way as well:

1. Modify database schemas to prepare to add Geo support for Project Wiki Repositories
2. Implement Geo support of Project Wiki Repositories behind a feature flag
3. Release Geo support of Project Wiki Repositories

It is also a good idea to first open a proof-of-concept merge request. It can be helpful for working out kinks and getting initial support and feedback from the Geo team. As an example, see the Proof of Concept to replicate Pipeline Artifacts.

You can look into the following example for implementing replication/verification for a new Git repository type:

• Add snippet repository verification

Modify database schemas to prepare to add Geo support for Project Wiki Repositories

Add the registry table to track replication and verification state

Geo secondary sites have a Geo tracking database independent of the main database. It is used to track the replication and verification state of all replicables. Every Model has a corresponding "registry" table in the Geo tracking database.

• Create the migration file in ee/db/geo/migrate:

  bin/rails generate migration CreateProjectWikiRepositoryRegistry --database geo

• Replace the contents of the migration file with the following. Note that we cannot add a foreign key constraint on project_id because the project_wiki_repositories table is in a different database. The application code must handle logic such as propagating deletions.

  # frozen_string_literal: true
  
  class CreateProjectWikiRepositoryRegistry < Gitlab::Database::Migration[2.0]
    def change
      create_table :project_wiki_repository_registry, id: :bigserial, force: :cascade do |t|
        t.bigint :project_id, null: false
        t.datetime_with_timezone :created_at, null: false
        t.datetime_with_timezone :last_synced_at
        t.datetime_with_timezone :retry_at
        t.datetime_with_timezone :verified_at
        t.datetime_with_timezone :verification_started_at
        t.datetime_with_timezone :verification_retry_at
        t.integer :state, default: 0, null: false, limit: 2
        t.integer :verification_state, default: 0, null: false, limit: 2
        t.integer :retry_count, default: 0, limit: 2, null: false
        t.integer :verification_retry_count, default: 0, limit: 2, null: false
        t.boolean :checksum_mismatch, default: false, null: false
        t.boolean :force_to_redownload, default: false, null: false
        t.boolean :missing_on_primary, default: false, null: false
        t.binary :verification_checksum
        t.binary :verification_checksum_mismatched
        t.text :verification_failure, limit: 255
        t.text :last_sync_failure, limit: 255
  
        t.index :project_id, name: :index_project_wiki_repository_registry_on_project_id, unique: true
        t.index :retry_at
        t.index :state
        # To optimize performance of ProjectWikiRepositoryRegistry.verification_failed_batch
        t.index :verification_retry_at, name: :project_wiki_repository_registry_failed_verification, order: "NULLS FIRST", where: "((state = 2) AND (verification_state = 3))"
        # To optimize performance of ProjectWikiRepositoryRegistry.needs_verification_count
        t.index :verification_state, name: :project_wiki_repository_registry_needs_verification, where: "((state = 2) AND (verification_state = ANY (ARRAY[0, 3])))"
        # To optimize performance of ProjectWikiRepositoryRegistry.verification_pending_batch
        t.index :verified_at, name: :project_wiki_repository_registry_pending_verification, order: "NULLS FIRST", where: "((state = 2) AND (verification_state = 0))"
      end
    end
  end

• If deviating from the above example, then be sure to order columns according to our guidelines.

• Add the new table to the database dictionary defined in ee/db/docs/:

  table_name: project_wiki_repository_registry
  description: Description example
  introduced_by_url: Merge request link
  milestone: Milestone example
  feature_categories:
   - Feature category example
  classes:
   - Class example
  gitlab_schema: gitlab_geo

• Run Geo tracking database migrations:

  bin/rake db:migrate:geo

• Be sure to commit the relevant changes in ee/db/geo/structure.sql and the file under ee/db/geo/schema_migrations

Add verification state to the Model

The Geo primary site needs to checksum every replicable so secondaries can verify their own checksums. To do this, Geo requires the Model to have an associated table to track verification state.

• Create the migration file in db/migrate:

  bin/rails generate migration CreateProjectWikiRepositoryStates

• Replace the contents of the migration file with:

  # frozen_string_literal: true
  
  class CreateProjectWikiRepositoryStates < Gitlab::Database::Migration[2.0]
    VERIFICATION_STATE_INDEX_NAME = "index_project_wiki_repository_states_on_verification_state"
    PENDING_VERIFICATION_INDEX_NAME = "index_project_wiki_repository_states_pending_verification"
    FAILED_VERIFICATION_INDEX_NAME = "index_project_wiki_repository_states_failed_verification"
    NEEDS_VERIFICATION_INDEX_NAME = "index_project_wiki_repository_states_needs_verification"
  
    enable_lock_retries!
  
    def up
      create_table :project_wiki_repository_states, id: false do |t|
        t.datetime_with_timezone :verification_started_at
        t.datetime_with_timezone :verification_retry_at
        t.datetime_with_timezone :verified_at
        t.references :project_wiki_repository, primary_key: true, default: nil, index: false, foreign_key: { on_delete: :cascade }
        t.integer :verification_state, default: 0, limit: 2, null: false
        t.integer :verification_retry_count, default: 0, limit: 2, null: false
        t.binary :verification_checksum, using: 'verification_checksum::bytea'
        t.text :verification_failure, limit: 255
  
        t.index :verification_state, name: VERIFICATION_STATE_INDEX_NAME
        t.index :verified_at, where: "(verification_state = 0)", order: { verified_at: 'ASC NULLS FIRST' }, name: PENDING_VERIFICATION_INDEX_NAME
        t.index :verification_retry_at, where: "(verification_state = 3)", order: { verification_retry_at: 'ASC NULLS FIRST' }, name: FAILED_VERIFICATION_INDEX_NAME
        t.index :verification_state, where: "(verification_state = 0 OR verification_state = 3)", name: NEEDS_VERIFICATION_INDEX_NAME
      end
    end
  
    def down
      drop_table :project_wiki_repository_states
    end
  end

• If deviating from the above example, then be sure to order columns according to our guidelines.

• Add the new table to the database dictionary defined in db/docs/:

  table_name: project_wiki_repository_states
  description: Description example
  introduced_by_url: Merge request link
  milestone: Milestone example
  feature_categories:
   - Feature category example
  classes:
   - Class example
  gitlab_schema: gitlab_main

• Run database migrations:

  bin/rake db:migrate

• Be sure to commit the relevant changes in db/structure.sql and the file under db/schema_migrations

• Add an entry for the state table in db/docs/project_wiki_repository_states.yml

  ---
  table_name: project_wiki_repository_states
  classes:
    - Geo::ProjectWikiRepositoryState
  feature_categories:
    - geo_replication
  description: Separate table for project wiki repository verification states
  introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/XXXXX
  milestone: '15.8'

That's all of the required database changes.

Implement Geo support of Project Wiki Repositories behind a feature flag

Step 1. Implement replication and verification

• Add the following lines to the wiki_repository model to accomplish some important tasks:

  • Include ::Geo::ReplicableModel in the Projects::WikiRepository class, and specify the Replicator class with_replicator Geo::ProjectWikiReplicator.
  • Include the ::Geo::VerifiableModel concern.
  • Delegate verification related methods to the project_wiki_repository_state model.
  • For verification, override some scopes to use the project_wiki_repository_states table instead of the model table.
  • Implement the verification_state_object method to return the object that holds the verification details
  • Override some methods to use the project_wiki_repository_states table in verification-related queries.

  Pay some attention to method pool_repository. Not every repository type uses repository pooling. As Geo prefers to use repository snapshotting, it can lead to data loss. Make sure to overwrite pool_repository so it returns nil for repositories that do not have pools.

  At this point the Projects::WikiRepository class should look like this:

  # frozen_string_literal: true
  
  class Projects::WikiRepository < ApplicationRecord
    ...
    include ::Geo::ReplicableModel
    include ::Geo::VerifiableModel
  
    delegate(*::Geo::VerificationState::VERIFICATION_METHODS, to: :project_wiki_repository_state)
  
    with_replicator Geo::ProjectWikiReplicator
  
    has_one :project_wiki_repository_state, autosave: false, inverse_of: :project_wiki_repository, class_name: 'Geo::ProjectWikiRepositoryState'
  
    after_save :save_verification_details
  
    scope :with_verification_state, ->(state) { joins(:project_wiki_repository_state).where(project_wiki_repository_states: { verification_state: verification_state_value(state) }) }
    scope :checksummed, -> { joins(:project_wiki_repository_state).where.not(project_wiki_repository_states: { verification_checksum: nil } ) }
    scope :not_checksummed, -> { joins(:project_wiki_repository_state).where(project_wiki_repository_states: { verification_checksum: nil } ) }
  
    scope :available_verifiables, -> { joins(:project_wiki_repository_state) }
  
    # Override the `all` default if not all records can be replicated. For an
    # example of an existing Model that needs to do this, see
    # `EE::MergeRequestDiff`.
    # scope :available_replicables, -> { all }
    def verification_state_object
  
      project_wiki_repository_state
    end
    ...
  
    class_methods do
      extend ::Gitlab::Utils::Override
      ...
  
      # @param primary_key_in [Range, Projects::WikiRepository] arg to pass to primary_key_in scope
      # @return [ActiveRecord::Relation<Projects::WikiRepository>] everything that should be synced to this node, restricted by primary key
      def replicables_for_current_secondary(primary_key_in)
        # This issue template does not help you write this method.
        #
        # This method is called only on Geo secondary sites. It is called when
        # we want to know which records to replicate. This is not easy to automate
        # because for example:
        #
        # * The "selective sync" feature allows admins to choose which namespaces #   to replicate, per secondary site. Most Models are scoped to a
        #   namespace, but the nature of the relationship to a namespace varies
        #   between Models.
        # * The "selective sync" feature allows admins to choose which shards to
        #   replicate, per secondary site. Repositories are associated with
        #   shards. Most blob types are not, but Project Uploads are.
        # * Remote stored replicables are not replicated, by default. But the
        #   setting `sync_object_storage` enables replication of remote stored
        #   replicables.
        #
        # Search the codebase for examples, and consult a Geo expert if needed.
      end
  
      override :verification_state_table_class
      def verification_state_table_class
        Geo::ProjectWikiRepositoryState
      end
    end
  
    # Geo checks this method in FrameworkRepositorySyncService to avoid
    # snapshotting repositories using object pools
    def pool_repository
      nil
    end
  
    def project_wiki_repository_state
      super || build_project_wiki_repository_state
    end
  
    ...
  end

• Implement Projects::WikiRepository.replicables_for_current_secondary above.

• Ensure Projects::WikiRepository.replicables_for_current_secondary is well-tested. Search the codebase for replicables_for_current_secondary to find examples of parameterized table specs. You may need to add more FactoryBot traits.

• Add the following shared examples to ee/spec/models/ee/projects/wiki_repository_spec.rb:

    include_examples 'a replicable model with a separate table for verification state' do
      let(:verifiable_model_record) { build(:project_wiki_repository) } # add extra params if needed to make sure the record is included in `available_verifiables`
      let(:unverifiable_model_record) { build(:project_wiki_repository) } # add extra params if needed to make sure the record is NOT included in `available_verifiables`
    end

• Create ee/app/replicators/geo/project_wiki_replicator.rb. Implement the #repository method which should return a <Repository> instance, and implement the class method .model to return the Projects::WikiRepository class:

  # frozen_string_literal: true
  
  module Geo
    class ProjectWikiReplicator < Gitlab::Geo::Replicator
      include ::Geo::RepositoryReplicatorStrategy
      extend ::Gitlab::Utils::Override
  
      def self.model
        ::Projects::WikiRepository
      end
  
      def repository
        model_record.repository
      end
  
      def self.git_access_class
        ::Gitlab::GitAccessWiki
      end
  
      def self.no_repo_message
        git_access_class.error_message(:no_repo)
      end
  
      override :verification_feature_flag_enabled?
      def self.verification_feature_flag_enabled?
        # We are adding verification at the same time as replication, so we
        # don't need to toggle verification separately from replication. When
        # the replication feature flag is off, then verification is also off
        # (see `VerifiableReplicator.verification_enabled?`)
        true
      end
  
      override :housekeeping_enabled?
      def self.housekeeping_enabled?
        # Remove this method if the new Git repository type supports git
        # repository housekeeping and the ::Projects::WikiRepository#git_garbage_collect_worker_klass
        # is implemented. If the data type requires any action to be performed
        # before running the housekeeping override the `before_housekeeping` method
        # (see `RepositoryReplicatorStrategy#before_housekeeping`)
        false
      end
    end
  end

• Make sure Geo push events are created. Usually it needs some change in the app/workers/post_receive.rb file. Example:

  def replicate_project_wiki_repository_changes(project_wiki_repository)
    if ::Gitlab::Geo.primary?
      project_wiki_repository.replicator.handle_after_update if project_wiki_repository
    end
  end

  See app/workers/post_receive.rb for more examples.

• Make sure the repository removal is also handled. You may need to add something like the following in the destroy service of the repository:

  project_wiki_repository.replicator.handle_after_destroy if project_wiki_repository.repository

• Make sure a Geo secondary site can request and download Project Wiki Repositories on the Geo primary site. You may need to make some changes to Gitlab::GitAccessCoolWidget. For example, see this change for Group-level Wikis.

• Make sure a Geo secondary site can replicate Project Wiki Repositories where repository does not exist on the Geo primary site. The only way to know about this is to parse the error text. You may need to make some changes to Gitlab::ProjectWikiReplicator.no_repo_message to return the proper error message. For example, see this change for Group-level Wikis.

• Generate the feature flag definition files by running the feature flag commands and following the command prompts:

  bin/feature-flag --ee geo_project_wiki_repository_replication --type development --group 'group::geo'

• Add this replicator class to the method replicator_classes in ee/lib/gitlab/geo.rb:

  REPLICATOR_CLASSES = [
    ::Geo::PackageFileReplicator,
    ::Geo::ProjectWikiReplicator
  ]

• Create ee/spec/replicators/geo/project_wiki_repository_replicator_spec.rb and perform the necessary setup to define the model_record variable for the shared examples:

  # frozen_string_literal: true
  
  require 'spec_helper'
  
  RSpec.describe Geo::ProjectWikiReplicator do
    let(:model_record) { build(:project_wiki_repository) }
  
    include_examples 'a repository replicator'
    include_examples 'a verifiable replicator'
  end

• Create ee/app/models/geo/project_wiki_repository_registry.rb:

  # frozen_string_literal: true
  
  module Geo
    class ProjectWikiRepositoryRegistry < Geo::BaseRegistry
      include ::Geo::ReplicableRegistry
      include ::Geo::VerifiableRegistry
  
      MODEL_CLASS = ::CoolWidget
      MODEL_FOREIGN_KEY = :project_id
  
      belongs_to :project_wiki_repository, class_name: 'CoolWidget'
    end
  end

• Update REGISTRY_CLASSES in ee/app/workers/geo/secondary/registry_consistency_worker.rb.

• Add a custom factory name if needed in def model_class_factory_name in ee/spec/support/helpers/ee/geo_helpers.rb.

• Update it 'creates missing registries for each registry class' in ee/spec/workers/geo/secondary/registry_consistency_worker_spec.rb.

• Add project_wiki_repository_registry to ActiveSupport::Inflector.inflections in config/initializers_before_autoloader/000_inflections.rb.

• Create ee/spec/factories/geo/project_wiki_repository_registry.rb:

  # frozen_string_literal: true
  
  FactoryBot.define do
    factory :geo_project_wiki_repository_registry, class: 'Geo::ProjectWikiRepositoryRegistry' do
      project_wiki_repository # This association should have data, like a file or repository
      state { Geo::ProjectWikiRepositoryRegistry.state_value(:pending) }
  
      trait :synced do
        state { Geo::ProjectWikiRepositoryRegistry.state_value(:synced) }
        last_synced_at { 5.days.ago }
      end
  
      trait :failed do
        state { Geo::ProjectWikiRepositoryRegistry.state_value(:failed) }
        last_synced_at { 1.day.ago }
        retry_count { 2 }
        last_sync_failure { 'Random error' }
      end
  
      trait :started do
        state { Geo::ProjectWikiRepositoryRegistry.state_value(:started) }
        last_synced_at { 1.day.ago }
        retry_count { 0 }
      end
  
      trait :verification_succeeded do
        verification_checksum { 'e079a831cab27bcda7d81cd9b48296d0c3dd92ef' }
        verification_state { Geo::ProjectWikiRepositoryRegistry.verification_state_value(:verification_succeeded) }
        verified_at { 5.days.ago }
      end
    end
  end

• Create ee/spec/models/geo/project_wiki_repository_registry_spec.rb:

  # frozen_string_literal: true
  
  require 'spec_helper'
  
  RSpec.describe Geo::ProjectWikiRepositoryRegistry, :geo, type: :model do
    let_it_be(:registry) { create(:geo_project_wiki_repository_registry) }
  
    specify 'factory is valid' do
      expect(registry).to be_valid
    end
  
    include_examples 'a Geo framework registry'
    include_examples 'a Geo verifiable registry'
  end

• Add the following to ee/spec/factories/project_wiki_repositories.rb:

  FactoryBot.modify do
    trait :verification_succeeded do
        with_file
        verification_checksum { 'abc' }
        verification_state { CoolWidget.verification_state_value(:verification_succeeded) }
    end
  
    trait :verification_failed do
        with_file
        verification_failure { 'Could not calculate the checksum' }
        verification_state { CoolWidget.verification_state_value(:verification_failed) }
    end
  end

  If there is not an existing factory for the object in spec/factories/project_wiki_repositories.rb, wrap the traits in FactoryBot.create instead of FactoryBot.modify.

• Make sure the factory also allows setting a project attribute. If the model does not have a direct relation to a project, you can use a transient attribute. Check out spec/factories/merge_request_diffs.rb for an example.

• Following the example of Merge Request Diffs add a Geo::ProjectWikiRepositoryState model in ee/app/models/geo/project_wiki_repository_state.rb:

  # frozen_string_literal: true
  
  module Geo
    class ProjectWikiRepositoryState < ApplicationRecord
      include EachBatch
      include ::Geo::VerificationStateDefinition
  
      self.primary_key = :project_id
  
      belongs_to :project_wiki_repository, inverse_of: :project_wiki_repository_state
  
      validates :verification_failure, length: { maximum: 255 }
      validates :verification_state, :project_wiki_repository, presence: true
    end
  end

• Add a factory for project_wiki_repository_state, in ee/spec/factories/geo/project_wiki_repository_states.rb:

  # frozen_string_literal: true
  
  FactoryBot.define do
    factory :geo_project_wiki_repository_state, class: 'Geo::ProjectWikiRepositoryState' do
      project_wiki_repository
  
      trait :checksummed do
        verification_checksum { 'abc' }
      end
  
      trait :checksum_failure do
        verification_failure { 'Could not calculate the checksum' }
      end
    end
  end

• Add [:project_wiki_repository, :remote_store] and [:geo_project_wiki_repository_state, any] to skipped in spec/models/factories_spec.rb

Step 2. Implement metrics gathering

Metrics are gathered by Geo::MetricsUpdateWorker, persisted in GeoNodeStatus for display in the UI, and sent to Prometheus:

• Add the following fields to Geo Node Status example responses in doc/api/geo_nodes.md:
  • project_wiki_repositories_count
  • project_wiki_repositories_checksum_total_count
  • project_wiki_repositories_checksummed_count
  • project_wiki_repositories_checksum_failed_count
  • project_wiki_repositories_synced_count
  • project_wiki_repositories_failed_count
  • project_wiki_repositories_registry_count
  • project_wiki_repositories_verification_total_count
  • project_wiki_repositories_verified_count
  • project_wiki_repositories_verification_failed_count
  • project_wiki_repositories_synced_in_percentage
  • project_wiki_repositories_verified_in_percentage
• Add the same fields to GET /geo_nodes/status example response in ee/spec/fixtures/api/schemas/public_api/v4/geo_node_status.json.
• Add the following fields to the Sidekiq metrics table in doc/administration/monitoring/prometheus/gitlab_metrics.md:

  | `geo_project_wiki_repositories` | Gauge | XX.Y | Number of Project Wiki Repositories on primary | `url` |
  | `geo_project_wiki_repositories_checksum_total` | Gauge | XX.Y | Number of Project Wiki Repositories checksummed successfully on primary | `url` |
  | `geo_project_wiki_repositories_checksummed` | Gauge | XX.Y | Number of Project Wiki Repositories failed to calculate the checksum on primary | `url` |
  | `geo_project_wiki_repositories_checksum_failed` | Gauge | XX.Y | Number of Project Wiki Repositories tried to checksum on primary | `url` |
  | `geo_project_wiki_repositories_synced` | Gauge | XX.Y | Number of syncable Project Wiki Repositories synced on secondary | `url` |
  | `geo_project_wiki_repositories_failed` | Gauge | XX.Y | Number of syncable Project Wiki Repositories failed to sync on secondary | `url` |
  | `geo_project_wiki_repositories_registry` | Gauge | XX.Y | Number of Project Wiki Repositories in the registry | `url` |
  | `geo_project_wiki_repositories_verification_total` | Gauge | XX.Y | Number of Project Wiki Repositories verified on secondary | `url` |
  | `geo_project_wiki_repositories_verified` | Gauge | XX.Y | Number of Project Wiki Repositories' verifications failed on secondary | `url` |
  | `geo_project_wiki_repositories_verification_failed` | Gauge | XX.Y | Number of Project Wiki Repositories' verifications tried on secondary | `url` |

Project Wiki Repository replication and verification metrics should now be available in the API, the Admin > Geo > Nodes view, and Prometheus.

Step 3. Implement the GraphQL API

The GraphQL API is used by Admin > Geo > Replication Details views, and is directly queryable by administrators.

• Add a new field to GeoNodeType in ee/app/graphql/types/geo/geo_node_type.rb:

  field :project_wiki_repository_registries, ::Types::Geo::ProjectWikiRepositoryRegistryType.connection_type,
        null: true,
        resolver: ::Resolvers::Geo::CoolWidgetRegistriesResolver,
        description: 'Find Project Wiki Repository registries on this Geo node. '\
                     'Ignored if `geo_project_wiki_repository_replication` feature flag is disabled.',
        alpha: { milestone: '15.5' } # Update the milestone

• Add the new project_wiki_repository_registries field name to the expected_fields array in ee/spec/graphql/types/geo/geo_node_type_spec.rb.

• Create ee/app/graphql/resolvers/geo/project_wiki_repository_registries_resolver.rb:

  # frozen_string_literal: true
  
  module Resolvers
    module Geo
      class CoolWidgetRegistriesResolver < BaseResolver
        type ::Types::Geo::GeoNodeType.connection_type, null: true
  
        include RegistriesResolver
      end
    end
  end

• Create ee/spec/graphql/resolvers/geo/project_wiki_repository_registries_resolver_spec.rb:

  # frozen_string_literal: true
  
  require 'spec_helper'
  
  RSpec.describe Resolvers::Geo::CoolWidgetRegistriesResolver do
    it_behaves_like 'a Geo registries resolver', :geo_project_wiki_repository_registry
  end

• Create ee/app/finders/geo/project_wiki_repository_registry_finder.rb:

  # frozen_string_literal: true
  
  module Geo
    class ProjectWikiRepositoryRegistryFinder
      include FrameworkRegistryFinder
    end
  end

• Create ee/spec/finders/geo/project_wiki_repository_registry_finder_spec.rb:

  # frozen_string_literal: true
  
  require 'spec_helper'
  
  RSpec.describe Geo::ProjectWikiRepositoryRegistryFinder do
    it_behaves_like 'a framework registry finder', :geo_project_wiki_repository_registry
  end

• Create ee/app/graphql/types/geo/project_wiki_repository_registry_type.rb:

  # frozen_string_literal: true
  
  module Types
    module Geo
      # rubocop:disable Graphql/AuthorizeTypes because it is included
      class ProjectWikiRepositoryRegistryType < BaseObject
        graphql_name 'ProjectWikiRepositoryRegistry'
  
        include ::Types::Geo::RegistryType
  
        description 'Represents the Geo replication and verification state of a project_wiki_repository'
  
        field :project_id, GraphQL::Types::ID, null: false, description: 'ID of the Project Wiki Repository.'
      end
      # rubocop:enable Graphql/AuthorizeTypes
    end
  end

• Create ee/spec/graphql/types/geo/project_wiki_repository_registry_type_spec.rb:

  # frozen_string_literal: true
  
  require 'spec_helper'
  
  RSpec.describe GitlabSchema.types['ProjectWikiRepositoryRegistry'] do
    it_behaves_like 'a Geo registry type'
  
    it 'has the expected fields (other than those included in RegistryType)' do
      expected_fields = %i[project_id]
  
      expect(described_class).to have_graphql_fields(*expected_fields).at_least
    end
  end

• Add integration tests for providing CoolWidget registry data to the frontend via the GraphQL API, by duplicating and modifying the following shared examples in ee/spec/requests/api/graphql/geo/registries_spec.rb:

  it_behaves_like 'gets registries for', {
    field_name: 'coolWidgetRegistries',
    registry_class_name: 'ProjectWikiRepositoryRegistry',
    registry_factory: :geo_project_wiki_repository_registry,
    registry_foreign_key_field_name: 'coolWidgetId'
  }

• Update the GraphQL reference documentation:

  bundle exec rake gitlab:graphql:compile_docs

Individual Project Wiki Repository replication and verification data should now be available via the GraphQL API.

Step 4. Handle batch destroy

If batch destroy logic is implemented for a replicable, then that logic must be "replicated" by Geo secondaries. The easiest way to do this is use Geo::BatchEventCreateWorker to bulk insert a delete event for each replicable.

For example, if FastDestroyAll is used, then you may be able to use begin_fast_destroy and finalize_fast_destroy hooks, like we did for uploads.

Or if a special service is used to batch delete records and their associated data, then you probably need to hook into that service, like we did for job artifacts.

As illustrated by the above two examples, batch destroy logic cannot be handled automatically by Geo secondaries without restricting the way other teams perform batch destroys. It is up to you to produce Geo::BatchEventCreateWorker attributes before the records are deleted, and then enqueue Geo::BatchEventCreateWorker after the records are deleted.

• Ensure that any batch destroy of this replicable is replicated to secondary sites
• Regardless of implementation details, please verify in specs that when the parent object is removed, the new Geo::Event records are created:

  describe '#destroy' do
    subject { create(:project_wiki_repository) }

    context 'when running in a Geo primary node' do
      let_it_be(:primary) { create(:geo_node, :primary) }
      let_it_be(:secondary) { create(:geo_node) }

      it 'logs an event to the Geo event log when bulk removal is used', :sidekiq_inline do
        stub_current_geo_node(primary)

        expect { subject.project.destroy! }.to change(Geo::Event.where(replicable_name: :project_wiki_repository, event_name: :deleted), :count).by(1)

        payload = Geo::Event.where(replicable_name: :project_wiki_repository, event_name: :deleted).last.payload

        expect(payload['model_record_id']).to eq(subject.id)
        expect(payload['blob_path']).to eq(subject.relative_path)
        expect(payload['uploader_class']).to eq('CoolWidgetUploader')
      end
    end
  end

Code Review

When requesting review from database reviewers:

• Include a comment mentioning that the change is based on a documented template.
• replicables_for_current_secondary and available_replicables may differ per Model. If their queries are new, then add query plans to the MR description. An easy place to gather SQL queries is your GDK's log/test.log when running tests of these methods.

Release Geo support of Project Wiki Repositories

• In the rollout issue you created when creating the feature flag, modify the Roll Out Steps:

  • Cross out any steps related to testing on production GitLab.com, because Geo is not running on production GitLab.com at the moment.
  • Add a step to Test replication and verification of Project Wiki Repositories on a non-GDK-deployment. For example, using GitLab Environment Toolkit.
  • Add a step to Ping the Geo PM and EM to coordinate testing. For example, you might add steps to generate Project Wiki Repositories, and then a Geo engineer may take it from there.

• In ee/config/feature_flags/development/geo_project_wiki_repository_replication.yml, set default_enabled: true

• In ee/app/graphql/types/geo/geo_node_type.rb, remove the alpha option for the released type:

  field :project_wiki_repository_registries, ::Types::Geo::ProjectWikiRepositoryRegistryType.connection_type,
        null: true,
        resolver: ::Resolvers::Geo::CoolWidgetRegistriesResolver,
        description: 'Find Project Wiki Repository registries on this Geo node. '\
                     'Ignored if `geo_project_wiki_repository_replication` feature flag is disabled.',
        alpha: { milestone: '15.5' } # Update the milestone

• Run bundle exec rake gitlab:graphql:compile_docs after the step above to regenerate the GraphQL docs.

• Add a row for Project Wiki Repositories to the Data types table in Geo data types support

• Add a row for Project Wiki Repositories to the Limitations on replication/verification table in Geo data types support. If the row already exists, then update it to show that Replication and Verification is released in the current version.