28 KiB
Replicate Cool Widgets
This issue is for implementing Geo replication and verification of Cool Widgets.
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:
- Modify database schemas to prepare to add Geo support for Cool Widgets
- Implement Geo support of Cool Widgets behind a feature flag
- Release Geo support of Cool Widgets
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 examples of MRs for implementing replication/verification for a new blob type:
- Add db changes and add verification for MR diffs using SSF
- Verify Terraform state versions
- Verify LFS objects
Modify database schemas to prepare to add Geo support for Cool Widgets
You might do this section in its own merge request, but it is not required.
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 geo_migration CreateCoolWidgetRegistry
-
Replace the contents of the migration file with the following. Note that we cannot add a foreign key constraint on
cool_widget_id
because thecool_widgets
table is in a different database. The application code must handle logic such as propagating deletions.# frozen_string_literal: true class CreateCoolWidgetRegistry < Gitlab::Database::Migration[1.0] disable_ddl_transaction! def up ActiveRecord::Base.transaction do create_table :cool_widget_registry, id: :bigserial, force: :cascade do |t| t.bigint :cool_widget_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.binary :verification_checksum t.binary :verification_checksum_mismatched t.text :verification_failure, limit: 255 t.text :last_sync_failure, limit: 255 t.index :cool_widget_id, name: :index_cool_widget_registry_on_cool_widget_id, unique: true t.index :retry_at t.index :state # To optimize performance of CoolWidgetRegistry.verification_failed_batch t.index :verification_retry_at, name: :cool_widget_registry_failed_verification, order: "NULLS FIRST", where: "((state = 2) AND (verification_state = 3))" # To optimize performance of CoolWidgetRegistry.needs_verification_count t.index :verification_state, name: :cool_widget_registry_needs_verification, where: "((state = 2) AND (verification_state = ANY (ARRAY[0, 3])))" # To optimize performance of CoolWidgetRegistry.verification_pending_batch t.index :verified_at, name: :cool_widget_registry_pending_verification, order: "NULLS FIRST", where: "((state = 2) AND (verification_state = 0))" end end end def down drop_table :cool_widget_registry end end
-
If deviating from the above example, then be sure to order columns according to our guidelines.
-
Run Geo tracking database migrations:
bin/rake db:migrate:geo
-
Be sure to commit the relevant changes in
ee/db/geo/structure.sql
Add verification state fields on the Geo primary site
The Geo primary site needs to checksum every replicable so secondaries can verify their own checksums. To do this, Geo requires fields on the Model. Add verification state fields to a separate table. Consult a database expert if needed.
Add verification state fields to a new table
-
Create the migration file in
db/migrate
:bin/rails generate migration CreateCoolWidgetStates
-
Replace the contents of the migration file with:
# frozen_string_literal: true class CreateCoolWidgetStates < Gitlab::Database::Migration[1.0] VERIFICATION_STATE_INDEX_NAME = "index_cool_widget_states_on_verification_state" PENDING_VERIFICATION_INDEX_NAME = "index_cool_widget_states_pending_verification" FAILED_VERIFICATION_INDEX_NAME = "index_cool_widget_states_failed_verification" NEEDS_VERIFICATION_INDEX_NAME = "index_cool_widget_states_needs_verification" enable_lock_retries! def up create_table :cool_widget_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 :cool_widget, primary_key: true, null: false, foreign_key: { on_delete: :cascade } t.integer :verification_state, default: 0, limit: 2, null: false t.integer :verification_retry_count, limit: 2 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 :cool_widget_states end end
-
If deviating from the above example, then be sure to order columns according to our guidelines.
-
Run database migrations:
bin/rake db:migrate
-
If
cool_widgets
is a high-traffic table, follow the database documentation to usewith_lock_retries
-
Be sure to commit the relevant changes in
db/structure.sql
That's all of the required database changes.
Implement Geo support of Cool Widgets behind a feature flag
Step 1. Implement replication and verification
-
Add the following lines to the
cool_widget
model to accomplish some important tasks:- Include
::Geo::ReplicableModel
in theCoolWidget
class, and specify the Replicator classwith_replicator Geo::CoolWidgetReplicator
. - Include the
::Geo::VerifiableModel
concern. - Delegate verification related methods to the
cool_widget_state
model. - For verification, override some scopes to use the
cool_widget_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
cool_widget_states
table in verification-related queries.
At this point the
CoolWidget
class should look like this:# frozen_string_literal: true class CoolWidget < ApplicationRecord ... include ::Geo::ReplicableModel include ::Geo::VerifiableModel delegate(*::Geo::VerificationState::VERIFICATION_METHODS, to: :cool_widget_state) with_replicator Geo::CoolWidgetReplicator mount_uploader :file, CoolWidgetUploader has_one :cool_widget_state, autosave: false, inverse_of: :cool_widget, class_name: 'Geo::CoolWidgetState' after_save :save_verification_details scope :with_verification_state, ->(state) { joins(:cool_widget_state).where(cool_widget_states: { verification_state: verification_state_value(state) }) } scope :checksummed, -> { joins(:cool_widget_state).where.not(cool_widget_states: { verification_checksum: nil } ) } scope :not_checksummed, -> { joins(:cool_widget_state).where(cool_widget_states: { verification_checksum: nil } ) } scope :available_verifiables, -> { joins(:cool_widget_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 cool_widget_state end ... class_methods do extend ::Gitlab::Utils::Override ... # @param primary_key_in [Range, CoolWidget] arg to pass to primary_key_in scope # @return [ActiveRecord::Relation<CoolWidget>] everything that should be synced to this node, restricted by primary key def self.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 CoolWidgetState end end ... def cool_widget_state super || build_cool_widget_state end ... end
- Include
-
Implement
CoolWidget.replicables_for_current_secondary
above. -
Ensure
CoolWidget.replicables_for_current_secondary
is well-tested. Search the codebase forreplicables_for_current_secondary
to find examples of parameterized table specs. You may need to add moreFactoryBot
traits. -
Add the following shared examples to
ee/spec/models/ee/cool_widget_spec.rb
:include_examples 'a replicable model with a separate table for verification state' do let(:verifiable_model_record) { build(:cool_widget) } # add extra params if needed to make sure the record is included in `available_verifiables` let(:unverifiable_model_record) { build(:cool_widget) } # add extra params if needed to make sure the record is NOT included in `available_verifiables` end
-
Create
ee/app/replicators/geo/cool_widget_replicator.rb
. Implement the#carrierwave_uploader
method which should return aCarrierWave::Uploader
, and implement the class method.model
to return theCoolWidget
class:# frozen_string_literal: true module Geo class CoolWidgetReplicator < Gitlab::Geo::Replicator include ::Geo::BlobReplicatorStrategy extend ::Gitlab::Utils::Override def self.model ::CoolWidget end def carrierwave_uploader model_record.file 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 end end
-
Generate the feature flag definition fileы by running the feature flag commands and following the command prompts:
bin/feature-flag --ee geo_cool_widget_replication --type development --group 'group::geo' bin/feature-flag --ee geo_cool_widget_verification --type development --group 'group::geo'
-
Add this replicator class to the method
replicator_classes
inee/lib/gitlab/geo.rb
:REPLICATOR_CLASSES = [ ::Geo::PackageFileReplicator, ::Geo::CoolWidgetReplicator ] end
-
Create
ee/spec/replicators/geo/cool_widget_replicator_spec.rb
and perform the necessary setup to define themodel_record
variable for the shared examples:# frozen_string_literal: true require 'spec_helper' RSpec.describe Geo::CoolWidgetReplicator do let(:model_record) { build(:cool_widget) } include_examples 'a blob replicator' include_examples 'a verifiable replicator' end
-
Create
ee/app/models/geo/cool_widget_registry.rb
:# frozen_string_literal: true class Geo::CoolWidgetRegistry < Geo::BaseRegistry include ::Geo::ReplicableRegistry include ::Geo::VerifiableRegistry MODEL_CLASS = ::CoolWidget MODEL_FOREIGN_KEY = :cool_widget_id belongs_to :cool_widget, class_name: 'CoolWidget' end
-
Update
REGISTRY_CLASSES
inee/app/workers/geo/secondary/registry_consistency_worker.rb
. -
Add a custom factory name if needed in
def model_class_factory_name
inee/spec/services/geo/registry_consistency_service_spec.rb
. -
Update
it 'creates missing registries for each registry class'
inee/spec/workers/geo/secondary/registry_consistency_worker_spec.rb
. -
Add
cool_widget_registry
toActiveSupport::Inflector.inflections
inconfig/initializers_before_autoloader/000_inflections.rb
. -
Create
ee/spec/factories/geo/cool_widget_registry.rb
:# frozen_string_literal: true FactoryBot.define do factory :geo_cool_widget_registry, class: 'Geo::CoolWidgetRegistry' do cool_widget # This association should have data, like a file or repository state { Geo::CoolWidgetRegistry.state_value(:pending) } trait :synced do state { Geo::CoolWidgetRegistry.state_value(:synced) } last_synced_at { 5.days.ago } end trait :failed do state { Geo::CoolWidgetRegistry.state_value(:failed) } last_synced_at { 1.day.ago } retry_count { 2 } last_sync_failure { 'Random error' } end trait :started do state { Geo::CoolWidgetRegistry.state_value(:started) } last_synced_at { 1.day.ago } retry_count { 0 } end trait :verification_succeeded do verification_checksum { 'e079a831cab27bcda7d81cd9b48296d0c3dd92ef' } verification_state { Geo::CoolWidgetRegistry.verification_state_value(:verification_succeeded) } verified_at { 5.days.ago } end end end
-
Create
ee/spec/models/geo/cool_widget_registry_spec.rb
:# frozen_string_literal: true require 'spec_helper' RSpec.describe Geo::CoolWidgetRegistry, :geo, type: :model do let_it_be(:registry) { create(:geo_cool_widget_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
spec/factories/cool_widgets.rb
: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
-
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 atransient
attribute. Check outspec/factories/merge_request_diffs.rb
for an example. -
Following the example of Merge Request Diffs add a
Geo::CoolWidgetState
model inee/app/models/ee/geo/cool_widget_state.rb
:module Geo class CoolWidgetState < ApplicationRecord include EachBatch include ::Geo::VerificationStateDefinition self.primary_key = :cool_widget_id belongs_to :cool_widget, inverse_of: :cool_widget_state validates :verification_failure, length: { maximum: 255 } validates :verification_state, :cool_widget, presence: true end end
-
Add a
factory
forcool_widget_state
, inee/spec/factories/geo/cool_widget_states.rb
:# frozen_string_literal: true FactoryBot.define do factory :geo_cool_widget_state, class: 'Geo::CoolWidgetState' do cool_widget trait(:checksummed) do verification_checksum { 'abc' } end trait(:checksum_failure) do verification_failure { 'Could not calculate the checksum' } end end end
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
:cool_widgets_count
cool_widgets_checksum_total_count
cool_widgets_checksummed_count
cool_widgets_checksum_failed_count
cool_widgets_synced_count
cool_widgets_failed_count
cool_widgets_registry_count
cool_widgets_verification_total_count
cool_widgets_verified_count
cool_widgets_verification_failed_count
cool_widgets_synced_in_percentage
cool_widgets_verified_in_percentage
-
Add the same fields to
GET /geo_nodes/status
example response inee/spec/fixtures/api/schemas/public_api/v4/geo_node_status.json
. -
Add the following fields to the
Sidekiq metrics
table indoc/administration/monitoring/prometheus/gitlab_metrics.md
:geo_cool_widgets
geo_cool_widgets_checksum_total
geo_cool_widgets_checksummed
geo_cool_widgets_checksum_failed
geo_cool_widgets_synced
geo_cool_widgets_failed
geo_cool_widgets_registry
geo_cool_widgets_verification_total
geo_cool_widgets_verified
geo_cool_widgets_verification_failed
-
Add the following to the parameterized table in the
context 'Replicator stats' do
block inee/spec/models/geo_node_status_spec.rb
:Geo::CoolWidgetReplicator | :cool_widget | :geo_cool_widget_registry
Cool Widget 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
inee/app/graphql/types/geo/geo_node_type.rb
:field :cool_widget_registries, ::Types::Geo::CoolWidgetRegistryType.connection_type, null: true, resolver: ::Resolvers::Geo::CoolWidgetRegistriesResolver, description: 'Find Cool Widget registries on this Geo node', feature_flag: :geo_cool_widget_replication
-
Add the new
cool_widget_registries
field name to theexpected_fields
array inee/spec/graphql/types/geo/geo_node_type_spec.rb
. -
Create
ee/app/graphql/resolvers/geo/cool_widget_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/cool_widget_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_cool_widget_registry end
-
Create
ee/app/finders/geo/cool_widget_registry_finder.rb
:# frozen_string_literal: true module Geo class CoolWidgetRegistryFinder include FrameworkRegistryFinder end end
-
Create
ee/spec/finders/geo/cool_widget_registry_finder_spec.rb
:# frozen_string_literal: true require 'spec_helper' RSpec.describe Geo::CoolWidgetRegistryFinder do it_behaves_like 'a framework registry finder', :geo_cool_widget_registry end
-
Create
ee/app/graphql/types/geo/cool_widget_registry_type.rb
:# frozen_string_literal: true module Types module Geo # rubocop:disable Graphql/AuthorizeTypes because it is included class CoolWidgetRegistryType < BaseObject include ::Types::Geo::RegistryType graphql_name 'CoolWidgetRegistry' description 'Represents the Geo replication and verification state of a cool_widget' field :cool_widget_id, GraphQL::ID_TYPE, null: false, description: 'ID of the Cool Widget' end end end
-
Create
ee/spec/graphql/types/geo/cool_widget_registry_type_spec.rb
:# frozen_string_literal: true require 'spec_helper' RSpec.describe GitlabSchema.types['CoolWidgetRegistry'] do it_behaves_like 'a Geo registry type' it 'has the expected fields (other than those included in RegistryType)' do expected_fields = %i[cool_widget_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: 'CoolWidgetRegistry', registry_factory: :geo_cool_widget_registry, registry_foreign_key_field_name: 'coolWidgetId' }
-
Update the GraphQL reference documentation:
bundle exec rake gitlab:graphql:compile_docs
Individual Cool Widget 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(:cool_widget) }
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: :cool_widget, event_name: :deleted), :count).by(1)
payload = Geo::Event.where(replicable_name: :cool_widget, 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
Release Geo support of Cool Widgets
-
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 Cool Widgets 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 Cool Widgets, and then a Geo engineer may take it from there.
-
In
ee/config/feature_flags/development/geo_cool_widget_replication.yml
, setdefault_enabled: true
-
In
ee/app/graphql/types/geo/geo_node_type.rb
, remove thefeature_flag
option for the released type:field :cool_widget_registries, ::Types::Geo::CoolWidgetRegistryType.connection_type, null: true, resolver: ::Resolvers::Geo::CoolWidgetRegistriesResolver, description: 'Find Cool Widget registries on this Geo node', feature_flag: :geo_cool_widget_replication # REMOVE THIS LINE
-
Run
bundle exec rake gitlab:graphql:compile_docs
after the step above to regenerate the GraphQL docs. -
Add a row for Cool Widgets to the
Data types
table in Geo data types support -
Add a row for Cool Widgets 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.