Sidekiq queue migration for HashedStorage::MigratorWorker

Migrate jobs from `storage_migrator` to
`hashed_storage:hashed_storage_migrator`.

db/post_migrate/20190124200344_migrate_storage_migrator_sidekiq_queue.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class MigrateStorageMigratorSidekiqQueue < ActiveRecord::Migration[5.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    sidekiq_queue_migrate 'storage_migrator', to: 'hashed_storage:hashed_storage_migrator'
+  end
+
+  def down
+    sidekiq_queue_migrate 'hashed_storage:hashed_storage_migrator', to: 'storage_migrator'
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20190115054216) do
+ActiveRecord::Schema.define(version: 20190124200344) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"

spec/migrations/migrate_storage_migrator_sidekiq_queue_spec.rb

@@ -0,0 +1,47 @@
+require 'spec_helper'
+require Rails.root.join('db', 'post_migrate', '20190124200344_migrate_storage_migrator_sidekiq_queue.rb')
+
+describe MigrateStorageMigratorSidekiqQueue, :sidekiq, :redis do
+  include Gitlab::Database::MigrationHelpers
+
+  context 'when there are jobs in the queues' do
+    it 'correctly migrates queue when migrating up' do
+      Sidekiq::Testing.disable! do
+        stubbed_worker(queue: :storage_migrator).perform_async(1, 5)
+
+        described_class.new.up
+
+        expect(sidekiq_queue_length('storage_migrator')).to eq 0
+        expect(sidekiq_queue_length('hashed_storage:hashed_storage_migrator')).to eq 1
+      end
+    end
+
+    it 'correctly migrates queue when migrating down' do
+      Sidekiq::Testing.disable! do
+        stubbed_worker(queue: :'hashed_storage:hashed_storage_migrator').perform_async(1, 5)
+
+        described_class.new.down
+
+        expect(sidekiq_queue_length('storage_migrator')).to eq 1
+        expect(sidekiq_queue_length('hashed_storage:hashed_storage_migrator')).to eq 0
+      end
+    end
+  end
+
+  context 'when there are no jobs in the queues' do
+    it 'does not raise error when migrating up' do
+      expect { described_class.new.up }.not_to raise_error
+    end
+
+    it 'does not raise error when migrating down' do
+      expect { described_class.new.down }.not_to raise_error
+    end
+  end
+
+  def stubbed_worker(queue:)
+    Class.new do
+      include Sidekiq::Worker
+      sidekiq_options queue: queue
+    end
+  end
+end