Proper fix for artifacts trace migration which is fully safe

app/workers/create_trace_artifact_worker.rb

@@ -2,9 +2,11 @@ class CreateTraceArtifactWorker
   include ApplicationWorker
   include PipelineQueue
 
+  # TODO: this worker should use BackgroundMigration or ObjectStorage queue
+
   def perform(job_id)
     Ci::Build.preload(:project, :user).find_by(id: job_id).try do |job|
-      Ci::CreateTraceArtifactService.new(job.project, job.user).execute(job)
+      job.trace.archive!
     end
   end
 end

lib/gitlab/ci/trace.rb

@@ -93,8 +93,39 @@ module Gitlab
         job.erase_old_trace!
       end
 
+      def archive!
+        return if trace_artifact
+
+        if current_path
+          File.open(current_path) do |f|
+            archive_stream!(f)
+            f.unlink
+          end
+        elsif old_trace
+          StringIO(old_trace).tap do |stream|
+            archive_stream!(stream)
+            job.erase_old_trace!
+          end
+        end
+      end
+
       private
 
+      def archive_stream!(stream)
+        file = Tempfile.new('trace.log')
+        size = IO.copy_stream(file, stream)
+        raise 'Not all saved' unless size == stream.size
+        file.close
+
+        job.create_job_artifacts_trace!(
+          project: job.project,
+          file_type: :trace,
+          file: file)
+      ensure
+        file&.close
+        file&.unlink
+      end
+
       def ensure_path
         return current_path if current_path