Setup Phabricator import

This sets up all the basics for importing Phabricator tasks into
GitLab issues.

To import all tasks from a Phabricator instance into GitLab, we'll
import all of them into a new project that will have its repository
disabled.

The import is hooked into a regular ProjectImport setup, but similar
to the GitHub parallel importer takes care of all the imports itself.

In this iteration, we're importing each page of tasks in a separate
sidekiq job.

The first thing we do when requesting a new page of tasks is schedule
the next page to be imported. But to avoid deadlocks, we only allow a
single job per worker type to run at the same time.

For now we're only importing basic Issue information, this should be
extended to richer information.

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/gitlab/phabricator_import.rb b/lib/gitlab/phabricator_import.rb
new file mode 100644
index 00000000000..3885a9934d5
--- /dev/null
+++ b/lib/gitlab/phabricator_import.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module PhabricatorImport
+    BaseError = Class.new(StandardError)
+
+    def self.available?
+      Feature.enabled?(:phabricator_import) &&
+        Gitlab::CurrentSettings.import_sources.include?('phabricator')
+    end
+  end
+end