Add the BG migration worker for the ci database

Add a CiDatabaseWorker, which will process background migrations
scheduled to execute agains the ci database.

app/workers/all_queues.yml

@@ -1947,6 +1947,15 @@
   :weight: 1
   :idempotent:
   :tags: []
+- :name: background_migration_ci_database
+  :worker_name: BackgroundMigration::CiDatabaseWorker
+  :feature_category: :database
+  :has_external_dependencies:
+  :urgency: :throttled
+  :resource_boundary: :unknown
+  :weight: 1
+  :idempotent:
+  :tags: []
 - :name: bulk_import
   :worker_name: BulkImportWorker
   :feature_category: :importers

app/workers/background_migration/ci_database_worker.rb

+# frozen_string_literal: true
+
+module BackgroundMigration
+  class CiDatabaseWorker # rubocop:disable Scalability/IdempotentWorker
+    include SingleDatabaseWorker
+
+    def self.tracking_database
+      @tracking_database ||= Gitlab::Database::CI_DATABASE_NAME
+    end
+  end
+end

app/workers/background_migration/single_database_worker.rb

@@ -32,10 +32,6 @@ module BackgroundMigration
       def tracking_database
         raise NotImplementedError, "#{self.name} does not implement #{__method__}"
       end
-
-      def unhealthy_metric_name
-        raise NotImplementedError, "#{self.name} does not implement #{__method__}"
-      end
     end
 
     # Performs the background migration.
@@ -55,8 +51,12 @@ module BackgroundMigration
 
     private
 
+    def tracking_database
+      self.class.tracking_database
+    end
+
     def job_coordinator
-      @job_coordinator ||= Gitlab::BackgroundMigration.coordinator_for_database(self.class.tracking_database)
+      @job_coordinator ||= Gitlab::BackgroundMigration.coordinator_for_database(tracking_database)
     end
 
     def perform_with_connection(class_name, arguments, lease_attempts)
@@ -91,7 +91,7 @@ module BackgroundMigration
       healthy_db = healthy_database?
       perform = lease_obtained && healthy_db
 
-      database_unhealthy_counter.increment if lease_obtained && !healthy_db
+      database_unhealthy_counter.increment(db_config_name: tracking_database) if lease_obtained && !healthy_db
 
       # When the DB is unhealthy or the lease can't be obtained after several tries,
       # then give up on the job and log a warning. Otherwise we could end up in
@@ -140,7 +140,7 @@ module BackgroundMigration
 
     def database_unhealthy_counter
       Gitlab::Metrics.counter(
-        self.class.unhealthy_metric_name,
+        :background_migration_database_health_reschedules,
         'The number of times a background migration is rescheduled because the database is unhealthy.'
       )
     end

app/workers/background_migration_worker.rb

@@ -6,8 +6,4 @@ class BackgroundMigrationWorker # rubocop:disable Scalability/IdempotentWorker
   def self.tracking_database
     @tracking_database ||= Gitlab::BackgroundMigration::DEFAULT_TRACKING_DATABASE
   end
-
-  def self.unhealthy_metric_name
-    @unhealthy_metric_name ||= :background_migration_database_health_reschedules
-  end
 end

config/sidekiq_queues.yml

@@ -55,6 +55,8 @@
   - 3
 - - background_migration
   - 1
+- - background_migration_ci_database
+  - 1
 - - bulk_import
   - 1
 - - bulk_imports_entity

lib/gitlab/background_migration/job_coordinator.rb

@@ -10,28 +10,32 @@ module Gitlab
     # Also provides a database connection to the correct tracking database.
     class JobCoordinator # rubocop:disable Metrics/ClassLength
       class << self
+        def for_tracking_database(tracking_database)
+          worker_class = worker_for_tracking_database[tracking_database]
+
+          if worker_class.nil?
+            raise ArgumentError, "tracking_database must be one of [#{worker_for_tracking_database.keys.join(', ')}]"
+          end
+
+          new(worker_class)
+        end
+
+        private
+
         def worker_classes
           @worker_classes ||= [
-            BackgroundMigrationWorker
+            ::BackgroundMigrationWorker,
+            ::BackgroundMigration::CiDatabaseWorker
           ].freeze
         end
 
         def worker_for_tracking_database
           @worker_for_tracking_database ||= worker_classes
+            .select { |worker_class| Gitlab::Database.has_config?(worker_class.tracking_database) }
             .index_by(&:tracking_database)
             .with_indifferent_access
             .freeze
         end
-
-        def for_tracking_database(tracking_database)
-          worker_class = worker_for_tracking_database[tracking_database]
-
-          if worker_class.nil?
-            raise ArgumentError, "tracking_database must be one of [#{worker_for_tracking_database.keys.join(', ')}]"
-          end
-
-          new(worker_class)
-        end
       end
 
       attr_reader :worker_class
@@ -146,7 +150,7 @@ module Gitlab
       def connection
         @connection ||= Gitlab::Database
           .database_base_models
-          .fetch(worker_class.tracking_database, Gitlab::Database::PRIMARY_DATABASE_NAME)
+          .fetch(worker_class.tracking_database)
           .connection
       end
     end

lib/gitlab/sidekiq_middleware/size_limiter/validator.rb

@@ -29,7 +29,7 @@ module Gitlab
         # The worker classes aren't constants here, because that would force
         # Application Settings to be loaded earlier causing failures loading
         # the environment in rake tasks
-        EXEMPT_WORKER_NAMES = ["BackgroundMigrationWorker", "Database::BatchedBackgroundMigrationWorker"].to_set
+        EXEMPT_WORKER_NAMES = %w[BackgroundMigrationWorker BackgroundMigration::CiDatabaseWorker Database::BatchedBackgroundMigrationWorker].to_set
         JOB_STATUS_KEY = 'size_limiter'
 
         class << self

spec/lib/gitlab/database/migrations/background_migration_helpers_spec.rb

@@ -299,7 +299,7 @@ RSpec.describe Gitlab::Database::Migrations::BackgroundMigrationHelpers do
 
       before do
         allow(Gitlab::BackgroundMigration).to receive(:coordinator_for_database)
-          .with('main').and_return(coordinator)
+          .with(tracking_database).and_return(coordinator)
 
         expect(coordinator).to receive(:migration_class_for)
           .with(job_class_name).at_least(:once) { job_class }
@@ -403,7 +403,7 @@ RSpec.describe Gitlab::Database::Migrations::BackgroundMigrationHelpers do
       end
 
       context 'when a specific coordinator is given' do
-        let(:coordinator) { Gitlab::BackgroundMigration::JobCoordinator.for_tracking_database('main') }
+        let(:coordinator) { Gitlab::BackgroundMigration::JobCoordinator.for_tracking_database(tracking_database) }
 
         it 'uses that coordinator' do
           expect(coordinator).to receive(:perform_in).with(10.minutes, 'Class', 'Hello', 'World').and_call_original
@@ -438,6 +438,10 @@ RSpec.describe Gitlab::Database::Migrations::BackgroundMigrationHelpers do
     it_behaves_like 'helpers that enqueue background migrations', BackgroundMigrationWorker, 'main'
   end
 
+  context 'when the migration is running against the ci database', if: Gitlab::Database.has_config?(:ci) do
+    it_behaves_like 'helpers that enqueue background migrations', BackgroundMigration::CiDatabaseWorker, 'ci'
+  end
+
   describe '#delete_job_tracking' do
     let!(:job_class_name) { 'TestJob' }
 

spec/support/shared_examples/workers/background_migration_worker_shared_examples.rb

 # frozen_string_literal: true
 
-RSpec.shared_examples 'it runs background migration jobs' do |tracking_database, metric_name|
+RSpec.shared_examples 'it runs background migration jobs' do |tracking_database|
   describe 'defining the job attributes' do
     it 'defines the data_consistency as always' do
       expect(described_class.get_data_consistency).to eq(:always)
@@ -33,16 +33,6 @@ RSpec.shared_examples 'it runs background migration jobs' do |tracking_database,
     end
   end
 
-  describe '.unhealthy_metric_name' do
-    it 'does not raise an error' do
-      expect { described_class.unhealthy_metric_name }.not_to raise_error
-    end
-
-    it 'overrides the method to return the unhealthy metric name' do
-      expect(described_class.unhealthy_metric_name).to eq(metric_name)
-    end
-  end
-
   describe '.minimum_interval' do
     it 'returns 2 minutes' do
       expect(described_class.minimum_interval).to eq(2.minutes.to_i)
@@ -189,11 +179,11 @@ RSpec.shared_examples 'it runs background migration jobs' do |tracking_database,
       end
 
       it 'increments the unhealthy counter' do
-        counter = Gitlab::Metrics.counter(metric_name, 'msg')
+        counter = Gitlab::Metrics.counter(:background_migration_database_health_reschedules, 'msg')
 
         expect(described_class).to receive(:perform_in)
 
-        expect { worker.perform('Foo', [10, 20]) }.to change { counter.get }.by(1)
+        expect { worker.perform('Foo', [10, 20]) }.to change { counter.get(db_config_name: tracking_database) }.by(1)
       end
 
       context 'when lease_attempts is 0' do

spec/workers/background_migration/ci_database_worker_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe BackgroundMigration::CiDatabaseWorker, :clean_gitlab_redis_shared_state, if: Gitlab::Database.has_config?(:ci) do
+  it_behaves_like 'it runs background migration jobs', 'ci'
+end

spec/workers/background_migration_worker_spec.rb

@@ -3,5 +3,5 @@
 require 'spec_helper'
 
 RSpec.describe BackgroundMigrationWorker, :clean_gitlab_redis_shared_state do
-  it_behaves_like 'it runs background migration jobs', 'main', :background_migration_database_health_reschedules
+  it_behaves_like 'it runs background migration jobs', 'main'
 end

spec/workers/every_sidekiq_worker_spec.rb

@@ -135,6 +135,7 @@ RSpec.describe 'Every Sidekiq worker' do
         'AutoDevops::DisableWorker' => 3,
         'AutoMergeProcessWorker' => 3,
         'BackgroundMigrationWorker' => 3,
+        'BackgroundMigration::CiDatabaseWorker' => 3,
         'BuildFinishedWorker' => 3,
         'BuildHooksWorker' => 3,
         'BuildQueueWorker' => 3,