Add single db variant of partitioning rake tasks

Add variants for the `gitlab:db:create_dynamic_partitions` rake task
that allow it to be run against a single database.

Also use the new single database variants when called in an `enhance`
block on other single database rake tasks like `db:migrate:main`.

lib/tasks/gitlab/db.rake

@@ -2,6 +2,14 @@
 
 databases = ActiveRecord::Tasks::DatabaseTasks.setup_initial_database_yaml
 
+def each_database(databases, include_geo: false)
+  ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |database|
+    next if !include_geo && database == 'geo'
+
+    yield database
+  end
+end
+
 namespace :gitlab do
   namespace :db do
     desc 'GitLab | DB | Manually insert schema migration version on all configured databases'
@@ -10,10 +18,10 @@ namespace :gitlab do
     end
 
     namespace :mark_migration_complete do
-      ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |database|
-        desc "Gitlab | DB | Manually insert schema migration version on #{database} database"
-        task database, [:version] => :environment do |_, args|
-          mark_migration_complete(args[:version], only_on: database)
+      each_database(databases) do |database_name|
+        desc "Gitlab | DB | Manually insert schema migration version on #{database_name} database"
+        task database_name, [:version] => :environment do |_, args|
+          mark_migration_complete(args[:version], only_on: database_name)
         end
       end
     end
@@ -39,10 +47,10 @@ namespace :gitlab do
     end
 
     namespace :drop_tables do
-      ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |database|
-        desc "GitLab | DB | Drop all tables on the #{database} database"
-        task database => :environment do
-          drop_tables(only_on: database)
+      each_database(databases) do |database_name|
+        desc "GitLab | DB | Drop all tables on the #{database_name} database"
+        task database_name => :environment do
+          drop_tables(only_on: database_name)
         end
       end
     end
@@ -155,6 +163,15 @@ namespace :gitlab do
       Gitlab::Database::Partitioning.sync_partitions
     end
 
+    namespace :create_dynamic_partitions do
+      each_database(databases) do |database_name|
+        desc "Create missing dynamic database partitions on the #{database_name} database"
+        task database_name => :environment do
+          Gitlab::Database::Partitioning.sync_partitions(only_on: database_name)
+        end
+      end
+    end
+
     # This is targeted towards deploys and upgrades of GitLab.
     # Since we're running migrations already at this time,
     # we also check and create partitions as needed here.
@@ -162,14 +179,12 @@ namespace :gitlab do
       Rake::Task['gitlab:db:create_dynamic_partitions'].invoke
     end
 
-    ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |name|
     # We'll temporarily skip this enhancement for geo, since in some situations we
     # wish to setup the geo database before the other databases have been setup,
     # and partition management attempts to connect to the main database.
-      next if name == 'geo'
-
-      Rake::Task["db:migrate:#{name}"].enhance do
-        Rake::Task['gitlab:db:create_dynamic_partitions'].invoke
+    each_database(databases) do |database_name|
+      Rake::Task["db:migrate:#{database_name}"].enhance do
+        Rake::Task["gitlab:db:create_dynamic_partitions:#{database_name}"].invoke
       end
     end
 
@@ -185,15 +200,15 @@ namespace :gitlab do
       Rake::Task['gitlab:db:create_dynamic_partitions'].invoke
     end
 
-    ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |name|
     # We'll temporarily skip this enhancement for geo, since in some situations we
     # wish to setup the geo database before the other databases have been setup,
     # and partition management attempts to connect to the main database.
-      next if name == 'geo'
-
-      Rake::Task["db:schema:load:#{name}"].enhance do
-        Rake::Task['gitlab:db:create_dynamic_partitions'].invoke
+    each_database(databases) do |database_name|
+      # :nocov:
+      Rake::Task["db:schema:load:#{database_name}"].enhance do
+        Rake::Task["gitlab:db:create_dynamic_partitions:#{database_name}"].invoke
       end
+      # :nocov:
     end
 
     desc "Clear all connections"
@@ -229,7 +244,7 @@ namespace :gitlab do
     end
 
     namespace :reindex do
-      ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |database_name|
+      each_database(databases) do |database_name|
         desc "Reindex #{database_name} database without downtime to eliminate bloat"
         task database_name => :environment do
           unless Gitlab::Database::Reindexing.enabled?

spec/tasks/gitlab/db_rake_spec.rb

@@ -80,6 +80,17 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
           run_rake_task('gitlab:db:mark_migration_complete:main', '[123]')
         end
       end
+
+      context 'with geo configured' do
+        before do
+          skip_unless_geo_configured
+        end
+
+        it 'does not create a task for the geo database' do
+          expect { run_rake_task('gitlab:db:mark_migration_complete:geo') }
+            .to raise_error(/Don't know how to build task 'gitlab:db:mark_migration_complete:geo'/)
+        end
+      end
     end
 
     context 'when the migration is already marked complete' do
@@ -319,6 +330,17 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
           run_rake_task('gitlab:db:drop_tables:main')
         end
       end
+
+      context 'with geo configured' do
+        before do
+          skip_unless_geo_configured
+        end
+
+        it 'does not create a task for the geo database' do
+          expect { run_rake_task('gitlab:db:drop_tables:geo') }
+            .to raise_error(/Don't know how to build task 'gitlab:db:drop_tables:geo'/)
+        end
+      end
     end
 
     def expect_objects_to_be_dropped(connection)
@@ -336,9 +358,61 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
     end
   end
 
+  describe 'create_dynamic_partitions' do
+    context 'with a single database' do
+      before do
+        skip_if_multiple_databases_are_setup
+      end
+
+      it 'delegates syncing of partitions without limiting databases' do
+        expect(Gitlab::Database::Partitioning).to receive(:sync_partitions)
+
+        run_rake_task('gitlab:db:create_dynamic_partitions')
+      end
+    end
+
+    context 'with multiple databases' do
+      before do
+        skip_if_multiple_databases_not_setup
+      end
+
+      context 'when running the multi-database variant' do
+        it 'delegates syncing of partitions without limiting databases' do
+          expect(Gitlab::Database::Partitioning).to receive(:sync_partitions)
+
+          run_rake_task('gitlab:db:create_dynamic_partitions')
+        end
+      end
+
+      context 'when running a single-database variant' do
+        it 'delegates syncing of partitions for the chosen database' do
+          expect(Gitlab::Database::Partitioning).to receive(:sync_partitions).with(only_on: 'main')
+
+          run_rake_task('gitlab:db:create_dynamic_partitions:main')
+        end
+      end
+    end
+
+    context 'with geo configured' do
+      before do
+        skip_unless_geo_configured
+      end
+
+      it 'does not create a task for the geo database' do
+        expect { run_rake_task('gitlab:db:create_dynamic_partitions:geo') }
+          .to raise_error(/Don't know how to build task 'gitlab:db:create_dynamic_partitions:geo'/)
+      end
+    end
+  end
+
   describe 'reindex' do
+    context 'with a single database' do
+      before do
+        skip_if_multiple_databases_are_setup
+      end
+
       it 'delegates to Gitlab::Database::Reindexing' do
-      expect(Gitlab::Database::Reindexing).to receive(:invoke)
+        expect(Gitlab::Database::Reindexing).to receive(:invoke).with(no_args)
 
         run_rake_task('gitlab:db:reindex')
       end
@@ -353,21 +427,46 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
       end
     end
 
-  databases = ActiveRecord::Tasks::DatabaseTasks.setup_initial_database_yaml
-  ActiveRecord::Tasks::DatabaseTasks.for_each(databases) do |database_name|
-    describe "reindex:#{database_name}" do
-      it 'delegates to Gitlab::Database::Reindexing' do
-        expect(Gitlab::Database::Reindexing).to receive(:invoke).with(database_name)
+    context 'with multiple databases' do
+      let(:base_models) { { 'main' => double(:model), 'ci' => double(:model) } }
 
-        run_rake_task("gitlab:db:reindex:#{database_name}")
+      before do
+        skip_if_multiple_databases_not_setup
+
+        allow(Gitlab::Database).to receive(:database_base_models).and_return(base_models)
+      end
+
+      it 'delegates to Gitlab::Database::Reindexing without a specific database' do
+        expect(Gitlab::Database::Reindexing).to receive(:invoke).with(no_args)
+
+        run_rake_task('gitlab:db:reindex')
+      end
+
+      context 'when the single database task is used' do
+        it 'delegates to Gitlab::Database::Reindexing with a specific database' do
+          expect(Gitlab::Database::Reindexing).to receive(:invoke).with('ci')
+
+          run_rake_task('gitlab:db:reindex:ci')
         end
 
         context 'when reindexing is not enabled' do
           it 'is a no-op' do
             expect(Gitlab::Database::Reindexing).to receive(:enabled?).and_return(false)
-          expect(Gitlab::Database::Reindexing).not_to receive(:invoke).with(database_name)
+            expect(Gitlab::Database::Reindexing).not_to receive(:invoke)
 
-          expect { run_rake_task("gitlab:db:reindex:#{database_name}") }.to raise_error(SystemExit)
+            expect { run_rake_task('gitlab:db:reindex:ci') }.to raise_error(SystemExit)
+          end
+        end
+      end
+
+      context 'with geo configured' do
+        before do
+          skip_unless_geo_configured
+        end
+
+        it 'does not create a task for the geo database' do
+          expect { run_rake_task('gitlab:db:reindex:geo') }
+            .to raise_error(/Don't know how to build task 'gitlab:db:reindex:geo'/)
         end
       end
     end
@@ -466,7 +565,7 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
       skip_if_multiple_databases_not_setup
     end
 
-    describe 'db:structure:dump' do
+    describe 'db:structure:dump against a single database' do
       it 'invokes gitlab:db:clean_structure_sql' do
         expect(Rake::Task['gitlab:db:clean_structure_sql']).to receive(:invoke).twice.and_return(true)
 
@@ -474,7 +573,7 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
       end
     end
 
-    describe 'db:schema:dump' do
+    describe 'db:schema:dump against a single database' do
       it 'invokes gitlab:db:clean_structure_sql' do
         expect(Rake::Task['gitlab:db:clean_structure_sql']).to receive(:invoke).once.and_return(true)
 
@@ -482,26 +581,24 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
       end
     end
 
-    describe 'db:migrate' do
-      it 'invokes gitlab:db:create_dynamic_partitions' do
-        expect(Rake::Task['gitlab:db:create_dynamic_partitions']).to receive(:invoke).once.and_return(true)
+    describe 'db:migrate against a single database' do
+      it 'invokes gitlab:db:create_dynamic_partitions for the same database' do
+        expect(Rake::Task['gitlab:db:create_dynamic_partitions:main']).to receive(:invoke).once.and_return(true)
 
         expect { run_rake_task('db:migrate:main') }.not_to raise_error
       end
     end
 
     describe 'db:migrate:geo' do
-      it 'does not invoke gitlab:db:create_dynamic_partitions' do
-        skip 'Skipping because geo database is not setup' unless geo_configured?
+      before do
+        skip_unless_geo_configured
+      end
 
+      it 'does not invoke gitlab:db:create_dynamic_partitions' do
         expect(Rake::Task['gitlab:db:create_dynamic_partitions']).not_to receive(:invoke)
 
         expect { run_rake_task('db:migrate:geo') }.not_to raise_error
       end
-
-      def geo_configured?
-        !!ActiveRecord::Base.configurations.configs_for(env_name: Rails.env, name: 'geo')
-      end
     end
   end
 
@@ -559,4 +656,12 @@ RSpec.describe 'gitlab:db namespace rake task', :silence_stdout do
 
     run_rake_task(test_task_name)
   end
+
+  def skip_unless_geo_configured
+    skip 'Skipping because the geo database is not configured' unless geo_configured?
+  end
+
+  def geo_configured?
+    !!ActiveRecord::Base.configurations.configs_for(env_name: Rails.env, name: 'geo')
+  end
 end