Delete file action for satellites

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

lib/gitlab/satellite/files/delete_file_action.rb

+require_relative 'file_action'
+
+module Gitlab
+  module Satellite
+    class DeleteFileAction < FileAction
+      # Deletes file and creates a new commit for it
+      #
+      # Returns false if committing the change fails
+      # Returns false if pushing from the satellite to bare repo failed or was rejected
+      # Returns true otherwise
+      def commit!(content, commit_message)
+        in_locked_and_timed_satellite do |repo|
+          prepare_satellite!(repo)
+
+          # create target branch in satellite at the corresponding commit from bare repo
+          repo.git.checkout({raise: true, timeout: true, b: true}, ref, "origin/#{ref}")
+
+          # update the file in the satellite's working dir
+          file_path_in_satellite = File.join(repo.working_dir, file_path)
+          File.delete(file_path_in_satellite)
+
+          # add removed file
+          repo.add(file_path_in_satellite)
+
+          # commit the changes
+          # will raise CommandFailed when commit fails
+          repo.git.commit(raise: true, timeout: true, a: true, m: commit_message)
+
+
+          # push commit back to bare repo
+          # will raise CommandFailed when push fails
+          repo.git.push({raise: true, timeout: true}, :origin, ref)
+
+          # everything worked
+          true
+        end
+      rescue Grit::Git::CommandFailed => ex
+        Gitlab::GitLogger.error(ex.message)
+        false
+      end
+    end
+  end
+end