Merge branch 'check_if_it_should_be_archived_in_backup' into 'master'

Check which folders and archives should be packed before passing to tar command.

If user uses backup task with SKIP and skips one of the archives listed(uploads, builds, artifacts) backup create will give an error: `Cannot stat: No such file or directory`.

This MR fixes that by checking for skipped items.
Additionally, compact everything to avoid `TypeError: no implicit conversion of nil into String` errors.

See merge request !1824

lib/backup/manager.rb

@@ -150,17 +150,15 @@ module Backup
     private
 
     def backup_contents
-      folders_to_backup + ["uploads.tar.gz", "builds.tar.gz", "artifacts.tar.gz", "backup_information.yml"]
+      folders_to_backup + archives_to_backup + ["backup_information.yml"]
     end
 
-    def folders_to_backup
-      folders = %w{repositories db}
-
-      if ENV["SKIP"]
-        return folders.reject{ |folder| ENV["SKIP"].include?(folder) }
-      end
+    def archives_to_backup
+      %w{uploads builds artifacts}.map{ |name| (name + ".tar.gz") unless skipped?(name) }.compact
+    end
 
-      folders
+    def folders_to_backup
+      %w{repositories db}.reject{ |name| skipped?(name) }
     end
 
     def settings

spec/tasks/gitlab/backup_rake_spec.rb

@@ -149,7 +149,7 @@ describe 'gitlab:app namespace rake task' do
       # Redirect STDOUT and run the rake task
       orig_stdout = $stdout
       $stdout = StringIO.new
-      ENV["SKIP"] = "repositories"
+      ENV["SKIP"] = "repositories,uploads"
       run_rake_task('gitlab:backup:create')
       $stdout = orig_stdout
 
@@ -180,6 +180,7 @@ describe 'gitlab:app namespace rake task' do
 
       expect(Rake::Task["gitlab:backup:db:restore"]).to receive :invoke
       expect(Rake::Task["gitlab:backup:repo:restore"]).not_to receive :invoke
+      expect(Rake::Task["gitlab:backup:uploads:restore"]).not_to receive :invoke
       expect(Rake::Task["gitlab:backup:builds:restore"]).to receive :invoke
       expect(Rake::Task["gitlab:backup:artifacts:restore"]).to receive :invoke
       expect(Rake::Task["gitlab:shell:setup"]).to receive :invoke