[ObjectStorage] Allow migrating back to local storage

We have a bunch of rake task to migrate from local storage to remote
storage, but nothing to migrate from remote storage to local.
We add that here.

This commits adds migration from object storage to local storage for:

- uploads
- artifacts (with metadata)
- traces
- LFS objects

app/models/ci/build.rb

@@ -118,8 +118,6 @@ module Ci
 
     scope :eager_load_job_artifacts, -> { includes(:job_artifacts) }
 
-    scope :with_artifacts_stored_locally, -> { with_existing_job_artifacts(Ci::JobArtifact.archive.with_files_stored_locally) }
-    scope :with_archived_trace_stored_locally, -> { with_existing_job_artifacts(Ci::JobArtifact.trace.with_files_stored_locally) }
     scope :with_artifacts_not_expired, ->() { with_artifacts_archive.where('artifacts_expire_at IS NULL OR artifacts_expire_at > ?', Time.now) }
     scope :with_expired_artifacts, ->() { with_artifacts_archive.where('artifacts_expire_at < ?', Time.now) }
     scope :last_month, ->() { where('created_at > ?', Date.today - 1.month) }

app/models/ci/job_artifact.rb

@@ -65,6 +65,7 @@ module Ci
     after_save :update_file_store, if: :saved_change_to_file?
 
     scope :with_files_stored_locally, -> { where(file_store: [nil, ::JobArtifactUploader::Store::LOCAL]) }
+    scope :with_files_stored_remotely, -> { where(file_store: ::JobArtifactUploader::Store::REMOTE) }
 
     scope :with_file_types, -> (file_types) do
       types = self.file_types.select { |file_type| file_types.include?(file_type) }.values

app/models/lfs_object.rb

@@ -9,6 +9,7 @@ class LfsObject < ApplicationRecord
   has_many :projects, -> { distinct }, through: :lfs_objects_projects
 
   scope :with_files_stored_locally, -> { where(file_store: LfsObjectUploader::Store::LOCAL) }
+  scope :with_files_stored_remotely, -> { where(file_store: LfsObjectUploader::Store::REMOTE) }
 
   validates :oid, presence: true, uniqueness: true
 

changelogs/unreleased/59036-object-to-local-storage.yml

+---
+title: "[ObjectStorage] Allow migrating back to local storage"
+merge_request: 16868
+author:
+type: added

doc/administration/job_artifacts.md

@@ -92,7 +92,7 @@ Use an object storage option like AWS S3 to store job artifacts.
 DANGER: **Danger:**
 If you're enabling S3 in [GitLab HA](high_availability/README.md), you will need to have an [NFS mount set up for CI traces and artifacts](high_availability/nfs.md#a-single-nfs-mount) or enable [live tracing](job_traces.md#new-live-trace-architecture). If these settings are not set, you will risk job traces disappearing or not being saved.
 
-### Object Storage Settings
+#### Object Storage Settings
 
 For source installations the following settings are nested under `artifacts:` and then `object_store:`. On Omnibus GitLab installs they are prefixed by `artifacts_object_store_`.
 
@@ -105,7 +105,7 @@ For source installations the following settings are nested under `artifacts:` an
 | `proxy_download` | Set to true to enable proxying all files served. Option allows to reduce egress traffic as this allows clients to download directly from remote storage instead of proxying all data | `false` |
 | `connection` | Various connection options described below | |
 
-#### S3 compatible connection settings
+##### S3 compatible connection settings
 
 The connection settings match those provided by [Fog](https://github.com/fog), and are as follows:
 
@@ -188,6 +188,14 @@ _The artifacts are stored by default in
    sudo -u git -H bundle exec rake gitlab:artifacts:migrate RAILS_ENV=production
    ```
 
+### Migrating from object storage to local storage
+
+In order to migrate back to local storage:
+
+1. Set both `direct_upload` and `background_upload` to false under the artifacts object storage settings. Don't forget to restart GitLab.
+1. Run `rake gitlab:artifacts:migrate_to_local` on your console.
+1. Disable `object_storage` for artifacts in `gitlab.rb`. Remember to restart GitLab afterwards.
+
 ## Expiring artifacts
 
 If an expiry date is used for the artifacts, they are marked for deletion

doc/administration/job_traces.md

@@ -59,46 +59,6 @@ job traces are automatically migrated to it along with the other job artifacts.
 
 See "Phase 4: uploading" in [Data flow](#data-flow) to learn about the process.
 
-## How to archive legacy job trace files
-
-Legacy job traces, which were created before GitLab 10.5, were not archived regularly.
-It's the same state with the "2: overwriting" in the above [Data flow](#data-flow).
-To archive those legacy job traces, please follow the instruction below.
-
-1. Execute the following command
-
-   ```bash
-   gitlab-rake gitlab:traces:archive
-   ```
-
-   After you executed this task, GitLab instance queues up Sidekiq jobs (asynchronous processes)
-   for migrating job trace files from local storage to object storage.
-   It could take time to complete the all migration jobs. You can check the progress by the following command
-
-   ```bash
-   sudo gitlab-rails console
-   ```
-
-   ```bash
-   [1] pry(main)> Sidekiq::Stats.new.queues['pipeline_background:archive_trace']
-   => 100
-   ```
-
-   If the count becomes zero, the archiving processes are done
-
-## How to migrate archived job traces to object storage
-
-> [Introduced][ce-21193] in GitLab 11.3.
-
-If job traces have already been archived into local storage, and you want to migrate those traces to object storage, please follow the instruction below.
-
-1. Ensure [Object storage integration for Job Artifacts](job_artifacts.md#object-storage-settings) is enabled
-1. Execute the following command
-
-   ```bash
-   gitlab-rake gitlab:traces:migrate
-   ```
-
 ## How to remove job traces
 
 There isn't a way to automatically expire old job logs, but it's safe to remove

doc/administration/merge_request_diffs.md

@@ -61,6 +61,9 @@ To enable external storage of merge request diffs, follow the instructions below
 
 ## Using object storage
 
+CAUTION: **WARNING:**
+  Currently migrating to object storage is **non-reversible**
+
 Instead of storing the external diffs on disk, we recommended the use of an object
 store like AWS S3 instead. This configuration relies on valid AWS credentials to
 be configured already.

doc/administration/raketasks/uploads/migrate.md

@@ -113,3 +113,39 @@ To migrate all uploads created by legacy uploaders, run:
 ```shell
 bundle exec rake gitlab:uploads:legacy:migrate
 ```
+
+## Migrate from object storage to local storage
+
+If you need to disable Object Storage for any reason, first you need to migrate
+your data out of Object Storage and back into your local storage.
+
+**Before proceeding, it is important to disable both `direct_upload` and `background_upload` under `uploads` settings in `gitlab.rb`**
+
+CAUTION: **Warning:**
+   **Extended downtime is required** so no new files are created in object storage during
+   the migration. A configuration setting will be added soon to allow migrating
+   from object storage to local files with only a brief moment of downtime for configuration changes.
+   See issue [gitlab-org/gitlab-ce#66144](https://gitlab.com/gitlab-org/gitlab-ce/issues/66144)
+
+### All-in-one rake task
+
+GitLab provides a wrapper rake task that migrates all uploaded files - avatars,
+logos, attachments, favicon, etc. - to local storage in one go. Under the hood,
+it invokes individual rake tasks to migrate files falling under each of this
+category one by one. For details on these rake tasks please [refer to the section above](#individual-rake-tasks),
+keeping in mind the task name in this case is `gitlab:uploads:migrate_to_local`.
+
+**Omnibus Installation**
+
+```bash
+gitlab-rake "gitlab:uploads:migrate_to_local:all"
+```
+
+**Source Installation**
+
+```bash
+sudo RAILS_ENV=production -u git -H bundle exec rake gitlab:uploads:migrate_to_local:all
+```
+
+After this is done, you may disable Object Storage by undoing the changes described
+in the instructions to [configure object storage](../../uploads.md#using-object-storage-core-only)

doc/workflow/lfs/lfs_administration.md

@@ -218,6 +218,14 @@ For source installations the settings are nested under `lfs:` and then
    will be forwarded to object storage unless `background_upload` is set to
    false.
 
+### Migrating back to local storage
+
+In order to migrate back to local storage:
+
+1. Set both `direct_upload` and `background_upload` to false under the LFS object storage settings. Don't forget to restart GitLab.
+1. Run `rake gitlab:lfs:migrate_to_local` on your console.
+1. Disable `object_storage` for LFS objects in `gitlab.rb`. Remember to restart GitLab afterwards.
+
 ## Storage statistics
 
 You can see the total storage used for LFS objects on groups and projects

lib/gitlab/artifacts/migration_helper.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Artifacts
+    class MigrationHelper
+      def migrate_to_remote_storage(&block)
+        artifacts = ::Ci::JobArtifact.with_files_stored_locally
+        migrate(artifacts, ObjectStorage::Store::REMOTE, &block)
+      end
+
+      def migrate_to_local_storage(&block)
+        artifacts = ::Ci::JobArtifact.with_files_stored_remotely
+        migrate(artifacts, ObjectStorage::Store::LOCAL, &block)
+      end
+
+      private
+
+      def batch_size
+        ENV.fetch('MIGRATION_BATCH_SIZE', 10).to_i
+      end
+
+      def migrate(artifacts, store, &block)
+        artifacts.find_each(batch_size: batch_size) do |artifact| # rubocop:disable CodeReuse/ActiveRecord
+          artifact.file.migrate!(store)
+
+          yield artifact if block
+        rescue => e
+          raise StandardError.new("Failed to transfer artifact of type #{artifact.file_type} and ID #{artifact.id} with error: #{e.message}")
+        end
+      end
+    end
+  end
+end

lib/gitlab/uploads/migration_helper.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Uploads
+    class MigrationHelper
+      attr_reader :logger
+
+      CATEGORIES = [%w(AvatarUploader Project :avatar),
+                    %w(AvatarUploader Group :avatar),
+                    %w(AvatarUploader User :avatar),
+                    %w(AttachmentUploader Note :attachment),
+                    %w(AttachmentUploader Appearance :logo),
+                    %w(AttachmentUploader Appearance :header_logo),
+                    %w(FaviconUploader Appearance :favicon),
+                    %w(FileUploader Project),
+                    %w(PersonalFileUploader Snippet),
+                    %w(NamespaceFileUploader Snippet),
+                    %w(FileUploader MergeRequest)].freeze
+
+      def initialize(args, logger)
+        prepare_variables(args, logger)
+      end
+
+      def migrate_to_remote_storage
+        @to_store = ObjectStorage::Store::REMOTE
+
+        uploads.each_batch(of: batch_size, &method(:enqueue_batch))
+      end
+
+      def migrate_to_local_storage
+        @to_store = ObjectStorage::Store::LOCAL
+
+        uploads(ObjectStorage::Store::REMOTE).each_batch(of: batch_size, &method(:enqueue_batch))
+      end
+
+      private
+
+      def batch_size
+        ENV.fetch('MIGRATION_BATCH_SIZE', 200).to_i
+      end
+
+      def prepare_variables(args, logger)
+        @mounted_as     = args.mounted_as&.gsub(':', '')&.to_sym
+        @uploader_class = args.uploader_class.constantize
+        @model_class    = args.model_class.constantize
+        @logger         = logger
+      end
+
+      def enqueue_batch(batch, index)
+        job = ObjectStorage::MigrateUploadsWorker.enqueue!(batch,
+                                                           @model_class,
+                                                           @mounted_as,
+                                                           @to_store)
+        logger.info(message: "[Uploads migration] Enqueued upload migration job", index: index, job_id: job)
+      rescue ObjectStorage::MigrateUploadsWorker::SanityCheckError => e
+        # continue for the next batch
+        logger.warn(message: "[Uploads migration] Could not enqueue batch", ids: batch.ids, reason: e.message) # rubocop:disable CodeReuse/ActiveRecord
+      end
+
+      # rubocop:disable CodeReuse/ActiveRecord
+      def uploads(store_type = [nil, ObjectStorage::Store::LOCAL])
+        Upload.class_eval { include EachBatch } unless Upload < EachBatch
+
+        Upload
+          .where(store: store_type,
+                 uploader: @uploader_class.to_s,
+                 model_type: @model_class.base_class.sti_name)
+      end
+      # rubocop:enable CodeReuse/ActiveRecord
+    end
+  end
+end

lib/tasks/gitlab/artifacts/migrate.rake

@@ -6,18 +6,31 @@ namespace :gitlab do
   namespace :artifacts do
     task migrate: :environment do
       logger = Logger.new(STDOUT)
-      logger.info('Starting transfer of artifacts')
+      logger.info('Starting transfer of artifacts to remote storage')
 
-      Ci::Build.joins(:project)
-        .with_artifacts_stored_locally
-        .find_each(batch_size: 10) do |build|
+      helper = Gitlab::Artifacts::MigrationHelper.new
 
-        build.artifacts_file.migrate!(ObjectStorage::Store::REMOTE)
-        build.artifacts_metadata.migrate!(ObjectStorage::Store::REMOTE)
+      begin
+        helper.migrate_to_remote_storage do |artifact|
+          logger.info("Transferred artifact ID #{artifact.id} of type #{artifact.file_type} with size #{artifact.size} to object storage")
+        end
+      rescue => e
+        logger.error(e.message)
+      end
+    end
+
+    task migrate_to_local: :environment do
+      logger = Logger.new(STDOUT)
+      logger.info('Starting transfer of artifacts to local storage')
+
+      helper = Gitlab::Artifacts::MigrationHelper.new
 
-        logger.info("Transferred artifact ID #{build.id} with size #{build.artifacts_size} to object storage")
+      begin
+        helper.migrate_to_local_storage do |artifact|
+          logger.info("Transferred artifact ID #{artifact.id} of type #{artifact.file_type} with size #{artifact.size} to local storage")
+        end
       rescue => e
-        logger.error("Failed to transfer artifacts of #{build.id} with error: #{e.message}")
+        logger.error(e.message)
       end
     end
   end

lib/tasks/gitlab/lfs/migrate.rake

@@ -17,5 +17,20 @@ namespace :gitlab do
           logger.error("Failed to transfer LFS object #{lfs_object.oid} with error: #{e.message}")
         end
     end
+
+    task migrate_to_local: :environment do
+      logger = Logger.new(STDOUT)
+      logger.info('Starting transfer of LFS files to local storage')
+
+      LfsObject.with_files_stored_remotely
+        .find_each(batch_size: 10) do |lfs_object|
+
+        lfs_object.file.migrate!(LfsObjectUploader::Store::LOCAL)
+
+        logger.info("Transferred LFS object #{lfs_object.oid} of size #{lfs_object.size.to_i.bytes} to local storage")
+      rescue => e
+        logger.error("Failed to transfer LFS object #{lfs_object.oid} with error: #{e.message}")
+      end
+    end
   end
 end

lib/tasks/gitlab/traces.rake

-require 'logger'
-require 'resolv-replace'
-
-desc "GitLab | Archive legacy traces to trace artifacts"
-namespace :gitlab do
-  namespace :traces do
-    task archive: :environment do
-      logger = Logger.new(STDOUT)
-      logger.info('Archiving legacy traces')
-
-      Ci::Build.finished.without_archived_trace
-        .order(id: :asc)
-        .find_in_batches(batch_size: 1000) do |jobs|
-        job_ids = jobs.map { |job| [job.id] }
-
-        ArchiveTraceWorker.bulk_perform_async(job_ids)
-
-        logger.info("Scheduled #{job_ids.count} jobs. From #{job_ids.min} to #{job_ids.max}")
-      end
-    end
-
-    task migrate: :environment do
-      logger = Logger.new(STDOUT)
-      logger.info('Starting transfer of job traces')
-
-      Ci::Build.joins(:project)
-        .with_archived_trace_stored_locally
-        .find_each(batch_size: 10) do |build|
-
-        build.job_artifacts_trace.file.migrate!(ObjectStorage::Store::REMOTE)
-
-        logger.info("Transferred job trace of #{build.id} to object storage")
-      rescue => e
-        logger.error("Failed to transfer artifacts of #{build.id} with error: #{e.message}")
-      end
-    end
-  end
-end

lib/tasks/gitlab/uploads/migrate.rake

@@ -3,19 +3,7 @@ namespace :gitlab do
     namespace :migrate do
       desc "GitLab | Uploads | Migrate all uploaded files to object storage"
       task all: :environment do
-        categories = [%w(AvatarUploader Project :avatar),
-                      %w(AvatarUploader Group :avatar),
-                      %w(AvatarUploader User :avatar),
-                      %w(AttachmentUploader Note :attachment),
-                      %w(AttachmentUploader Appearance :logo),
-                      %w(AttachmentUploader Appearance :header_logo),
-                      %w(FaviconUploader Appearance :favicon),
-                      %w(FileUploader Project),
-                      %w(PersonalFileUploader Snippet),
-                      %w(NamespaceFileUploader Snippet),
-                      %w(FileUploader MergeRequest)]
-
-        categories.each do |args|
+        Gitlab::Uploads::MigrationHelper::CATEGORIES.each do |args|
           Rake::Task["gitlab:uploads:migrate"].invoke(*args)
           Rake::Task["gitlab:uploads:migrate"].reenable
         end
@@ -25,34 +13,23 @@ namespace :gitlab do
     # The following is the actual rake task that migrates uploads of specified
     # category to object storage
     desc 'GitLab | Uploads | Migrate the uploaded files of specified type to object storage'
-    task :migrate, [:uploader_class, :model_class, :mounted_as] => :environment do |task, args|
-      batch_size     = ENV.fetch('BATCH', 200).to_i
-      @to_store      = ObjectStorage::Store::REMOTE
-      @mounted_as    = args.mounted_as&.gsub(':', '')&.to_sym
-      @uploader_class = args.uploader_class.constantize
-      @model_class    = args.model_class.constantize
-
-      uploads.each_batch(of: batch_size, &method(:enqueue_batch))
+    task :migrate, [:uploader_class, :model_class, :mounted_as] => :environment do |_t, args|
+      Gitlab::Uploads::MigrationHelper.new(args, Logger.new(STDOUT)).migrate_to_remote_storage
     end
 
-    def enqueue_batch(batch, index)
-      job = ObjectStorage::MigrateUploadsWorker.enqueue!(batch,
-                                                         @model_class,
-                                                         @mounted_as,
-                                                         @to_store)
-      puts "Enqueued job ##{index}: #{job}"
-    rescue ObjectStorage::MigrateUploadsWorker::SanityCheckError => e
-      # continue for the next batch
-      puts "Could not enqueue batch (#{batch.ids}) #{e.message}".color(:red)
+    namespace :migrate_to_local do
+      desc "GitLab | Uploads | Migrate all uploaded files to local storage"
+      task all: :environment do
+        Gitlab::Uploads::MigrationHelper::CATEGORIES.each do |args|
+          Rake::Task["gitlab:uploads:migrate_to_local"].invoke(*args)
+          Rake::Task["gitlab:uploads:migrate_to_local"].reenable
+        end
+      end
     end
 
-    def uploads
-      Upload.class_eval { include EachBatch } unless Upload < EachBatch
-
-      Upload
-        .where(store: [nil, ObjectStorage::Store::LOCAL],
-               uploader: @uploader_class.to_s,
-               model_type: @model_class.base_class.sti_name)
+    desc 'GitLab | Uploads | Migrate the uploaded files of specified type to local storage'
+    task :migrate_to_local, [:uploader_class, :model_class, :mounted_as] => :environment do |_t, args|
+      Gitlab::Uploads::MigrationHelper.new(args, Logger.new(STDOUT)).migrate_to_local_storage
     end
   end
 end

spec/tasks/gitlab/artifacts/migrate_rake_spec.rb

@@ -11,10 +11,11 @@ describe 'gitlab:artifacts namespace rake task' do
     stub_artifacts_object_storage(enabled: object_storage_enabled)
   end
 
-  subject { run_rake_task('gitlab:artifacts:migrate') }
+  describe 'gitlab:artifacts:migrate' do
+    subject { run_rake_task('gitlab:artifacts:migrate') }
 
-  context 'job artifacts' do
     let!(:artifact) { create(:ci_job_artifact, :archive, file_store: store) }
+    let!(:job_trace) { create(:ci_job_artifact, :trace, file_store: store) }
 
     context 'when local storage is used' do
       let(:store) { ObjectStorage::Store::LOCAL }
@@ -27,6 +28,7 @@ describe 'gitlab:artifacts namespace rake task' do
           subject
 
           expect(artifact.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
+          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
         end
       end
 
@@ -37,6 +39,7 @@ describe 'gitlab:artifacts namespace rake task' do
           subject
 
           expect(artifact.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
+          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
         end
       end
 
@@ -45,6 +48,7 @@ describe 'gitlab:artifacts namespace rake task' do
           subject
 
           expect(artifact.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
+          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
         end
       end
     end
@@ -57,6 +61,40 @@ describe 'gitlab:artifacts namespace rake task' do
         subject
 
         expect(artifact.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
+        expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
+      end
+    end
+  end
+
+  describe 'gitlab:artifacts:migrate_to_local' do
+    let(:object_storage_enabled) { true }
+
+    subject { run_rake_task('gitlab:artifacts:migrate_to_local') }
+
+    let!(:artifact) { create(:ci_job_artifact, :archive, file_store: store) }
+    let!(:job_trace) { create(:ci_job_artifact, :trace, file_store: store) }
+
+    context 'when remote storage is used' do
+      let(:store) { ObjectStorage::Store::REMOTE }
+
+      context 'and job has remote file store defined' do
+        it "migrates file to local storage" do
+          subject
+
+          expect(artifact.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
+          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
+        end
+      end
+    end
+
+    context 'when local storage is used' do
+      let(:store) { ObjectStorage::Store::LOCAL }
+
+      it 'file stays on local storage' do
+        subject
+
+        expect(artifact.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
+        expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
       end
     end
   end

spec/tasks/gitlab/lfs/migrate_rake_spec.rb

@@ -5,32 +5,49 @@ describe 'gitlab:lfs namespace rake task' do
     Rake.application.rake_require 'tasks/gitlab/lfs/migrate'
   end
 
-  describe 'migrate' do
+  context 'migration tasks' do
     let(:local) { ObjectStorage::Store::LOCAL }
     let(:remote) { ObjectStorage::Store::REMOTE }
-    let!(:lfs_object) { create(:lfs_object, :with_file, file_store: local) }
 
-    def lfs_migrate
-      run_rake_task('gitlab:lfs:migrate')
+    before do
+      stub_lfs_object_storage(background_upload: false, direct_upload: false)
     end
 
-    context 'object storage disabled' do
-      before do
-        stub_lfs_object_storage(enabled: false)
+    describe 'migrate' do
+      subject { run_rake_task('gitlab:lfs:migrate') }
+
+      let!(:lfs_object) { create(:lfs_object, :with_file) }
+
+      context 'object storage disabled' do
+        before do
+          stub_lfs_object_storage(enabled: false)
+        end
+
+        it "doesn't migrate files" do
+          expect { subject }.not_to change { lfs_object.reload.file_store }
+        end
       end
 
-      it "doesn't migrate files" do
-        expect { lfs_migrate }.not_to change { lfs_object.reload.file_store }
+      context 'object storage enabled' do
+        it 'migrates local file to object storage' do
+          expect { subject }.to change { lfs_object.reload.file_store }.from(local).to(remote)
+        end
       end
     end
 
-    context 'object storage enabled' do
+    describe 'migrate_to_local' do
+      subject { run_rake_task('gitlab:lfs:migrate_to_local') }
+
+      let(:lfs_object) { create(:lfs_object, :with_file, :object_storage) }
+
       before do
-        stub_lfs_object_storage
+        stub_lfs_object_storage(background_upload: false, direct_upload: true)
       end
 
-      it 'migrates local file to object storage' do
-        expect { lfs_migrate }.to change { lfs_object.reload.file_store }.from(local).to(remote)
+      context 'object storage enabled' do
+        it 'migrates remote files to local storage' do
+          expect { subject }.to change { lfs_object.reload.file_store }.from(remote).to(local)
+        end
       end
     end
   end

spec/tasks/gitlab/traces_rake_spec.rb

-require 'rake_helper'
-
-describe 'gitlab:traces rake tasks' do
-  before do
-    Rake.application.rake_require 'tasks/gitlab/traces'
-  end
-
-  describe 'gitlab:traces:archive' do
-    shared_examples 'passes the job id to worker' do
-      it do
-        expect(ArchiveTraceWorker).to receive(:bulk_perform_async).with([[job.id]])
-
-        run_rake_task('gitlab:traces:archive')
-      end
-    end
-
-    shared_examples 'does not pass the job id to worker' do
-      it do
-        expect(ArchiveTraceWorker).not_to receive(:bulk_perform_async)
-
-        run_rake_task('gitlab:traces:archive')
-      end
-    end
-
-    context 'when trace file stored in default path' do
-      let!(:job) { create(:ci_build, :success, :trace_live) }
-
-      it_behaves_like 'passes the job id to worker'
-    end
-
-    context 'when trace is stored in database' do
-      let!(:job) { create(:ci_build, :success) }
-
-      before do
-        job.update_column(:trace, 'trace in db')
-      end
-
-      it_behaves_like 'passes the job id to worker'
-    end
-
-    context 'when job has trace artifact' do
-      let!(:job) { create(:ci_build, :success) }
-
-      before do
-        create(:ci_job_artifact, :trace, job: job)
-      end
-
-      it_behaves_like 'does not pass the job id to worker'
-    end
-
-    context 'when job is not finished yet' do
-      let!(:build) { create(:ci_build, :running, :trace_live) }
-
-      it_behaves_like 'does not pass the job id to worker'
-    end
-  end
-
-  describe 'gitlab:traces:migrate' do
-    let(:object_storage_enabled) { false }
-
-    before do
-      stub_artifacts_object_storage(enabled: object_storage_enabled)
-    end
-
-    subject { run_rake_task('gitlab:traces:migrate') }
-
-    let!(:job_trace) { create(:ci_job_artifact, :trace, file_store: store) }
-
-    context 'when local storage is used' do
-      let(:store) { ObjectStorage::Store::LOCAL }
-
-      context 'and job does not have file store defined' do
-        let(:object_storage_enabled) { true }
-        let(:store) { nil }
-
-        it "migrates file to remote storage" do
-          subject
-
-          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
-        end
-      end
-
-      context 'and remote storage is defined' do
-        let(:object_storage_enabled) { true }
-
-        it "migrates file to remote storage" do
-          subject
-
-          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
-        end
-      end
-
-      context 'and remote storage is not defined' do
-        it "fails to migrate to remote storage" do
-          subject
-
-          expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::LOCAL)
-        end
-      end
-    end
-
-    context 'when remote storage is used' do
-      let(:object_storage_enabled) { true }
-      let(:store) { ObjectStorage::Store::REMOTE }
-
-      it "file stays on remote storage" do
-        subject
-
-        expect(job_trace.reload.file_store).to eq(ObjectStorage::Store::REMOTE)
-      end
-    end
-  end
-end

spec/tasks/gitlab/uploads/migrate_rake_spec.rb

 require 'rake_helper'
 
-describe 'gitlab:uploads:migrate rake tasks' do
+describe 'gitlab:uploads:migrate and migrate_to_local rake tasks' do
   let(:model_class) { nil }
   let(:uploader_class) { nil }
   let(:mounted_as) { nil }
   let(:batch_size) { 3 }
 
   before do
-    stub_env('BATCH', batch_size.to_s)
+    stub_env('MIGRATION_BATCH_SIZE', batch_size.to_s)
     stub_uploads_object_storage(uploader_class)
     Rake.application.rake_require 'tasks/gitlab/uploads/migrate'
 
     allow(ObjectStorage::MigrateUploadsWorker).to receive(:perform_async)
   end
 
-  def run
+  def run(task)
     args = [uploader_class.to_s, model_class.to_s, mounted_as].compact
-    run_rake_task("gitlab:uploads:migrate", *args)
+    run_rake_task(task, *args)
   end
 
   shared_examples 'enqueue jobs in batch' do |batch:|
-    it do
+    it 'migrates local storage to remote object storage' do
       expect(ObjectStorage::MigrateUploadsWorker)
         .to receive(:perform_async).exactly(batch).times
-              .and_return("A fake job.")
+        .and_return("A fake job.")
 
-      run
+      run('gitlab:uploads:migrate')
+    end
+
+    it 'migrates remote object storage to local storage' do
+      expect(Upload).to receive(:where).exactly(batch + 1).times { Upload.all }
+      expect(ObjectStorage::MigrateUploadsWorker)
+        .to receive(:perform_async)
+        .with(anything, model_class.name, mounted_as, ObjectStorage::Store::LOCAL)
+        .exactly(batch).times
+        .and_return("A fake job.")
+
+      run('gitlab:uploads:migrate_to_local')
     end
   end
 

spec/uploaders/workers/object_storage/migrate_uploads_worker_spec.rb

@@ -11,8 +11,8 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
   let(:uploads) { Upload.all }
   let(:to_store) { ObjectStorage::Store::REMOTE }
 
-  def perform(uploads)
-    described_class.new.perform(uploads.ids, model_class.to_s, mounted_as, to_store)
+  def perform(uploads, store = nil)
+    described_class.new.perform(uploads.ids, model_class.to_s, mounted_as, store || to_store)
   rescue ObjectStorage::MigrateUploadsWorker::Report::MigrationFailures
     # swallow
   end
@@ -97,12 +97,28 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
 
       it_behaves_like 'outputs correctly', success: 10
 
-      it 'migrates files' do
+      it 'migrates files to remote storage' do
         perform(uploads)
 
         expect(Upload.where(store: ObjectStorage::Store::LOCAL).count).to eq(0)
       end
 
+      context 'reversed' do
+        let(:to_store) { ObjectStorage::Store::LOCAL }
+
+        before do
+          perform(uploads, ObjectStorage::Store::REMOTE)
+        end
+
+        it 'migrates files to local storage' do
+          expect(Upload.where(store: ObjectStorage::Store::REMOTE).count).to eq(10)
+
+          perform(uploads)
+
+          expect(Upload.where(store: ObjectStorage::Store::LOCAL).count).to eq(10)
+        end
+      end
+
       context 'migration is unsuccessful' do
         before do
           allow_any_instance_of(ObjectStorage::Concern)