first iteration of the gitlab:uploads:migrate task

app/models/upload.rb

@@ -36,8 +36,8 @@ class Upload < ActiveRecord::Base
     self.checksum = self.class.hexdigest(absolute_path)
   end
 
-  def build_uploader
-    uploader_class.new(model, mount_point, **uploader_context).tap do |uploader|
+  def build_uploader(mounted_as = nil)
+    uploader_class.new(model, mounted_as || mount_point).tap do |uploader|
       uploader.upload = self
       uploader.retrieve_from_store!(identifier)
     end

lib/tasks/gitlab/uploads.rake

@@ -19,6 +19,77 @@ namespace :gitlab do
       puts 'Done!'
     end
 
+    desc 'GitLab | Uploads | Migrate the uploaded files to object storage'
+    task :migrate, [:uploader_class, :model_class, :mounted_as] => :environment do |task, args|
+      MIGRATE_TO_STORE = ObjectStorage::Store::REMOTE
+
+      class MigrationResult
+        attr_reader :upload
+        attr_accessor :error
+
+        def initialize(upload, error = nil)
+          @upload, @error = upload, error
+        end
+
+        def success?
+          error.nil?
+        end
+
+        def to_s
+          success? ? "Migration sucessful." : "Error while migrating #{upload.id}: #{error.message}"
+        end
+      end
+
+      uploader_class = args.uploader_class.constantize
+      model_class = args.model_class.constantize
+      mounted_as = args.mounted_as&.gsub(':', '')&.to_sym
+
+      global_results = []
+      Upload.preload(:model)
+        .where.not(store: MIGRATE_TO_STORE)
+        .where(uploader: uploader_class.to_s,
+               model_type: model_class.to_s)
+        .in_batches(of: batch_size) do |batch|
+
+        results = migrate(build_uploaders(batch, mounted_as))
+        report(results)
+
+        global_results.concat(results)
+      end
+
+      puts "\n === Migration summary ==="
+      report(global_results)
+    end
+
+    def report(results)
+      results = results.group_by(&:success?)
+      success, errors = [
+        results.fetch(true, []),
+        results.fetch(false, [])
+      ]
+      batch_color = errors.count == 0 ? :green : :red
+
+      puts "Migrated #{success.count}/#{success.count + errors.count} files.".color(batch_color)
+      errors.each { |e| puts("\t#{e}").color(:red) }
+    end
+
+    def build_uploaders(uploads, mounted_as)
+      uploads.map { |upload| upload.build_uploader(mounted_as) }
+    end
+
+    def migrate(uploaders)
+      uploaders.map do |uploader|
+        result = MigrationResult.new(uploader.upload)
+        begin
+          uploader.migrate!(MIGRATE_TO_STORE)
+          result
+        rescue CarrierWave::UploadError => e
+          result.error = e
+          result
+        end
+      end
+    end
+
     def batch_size
       ENV.fetch('BATCH', 200).to_i
     end