closed by field added

app/models/issue.rb

@@ -27,6 +27,7 @@ class Issue < ActiveRecord::Base
 
   belongs_to :project
   belongs_to :moved_to, class_name: 'Issue'
+  belongs_to :closed_by, class_name: 'User'
 
   has_internal_id :iid, scope: :project, init: ->(s) { s&.project&.issues&.maximum(:iid) }
 

app/services/issues/close_service.rb

@@ -23,6 +23,7 @@ module Issues
       end
 
       if project.issues_enabled? && issue.close
+        issue.update(closed_by: current_user)
         event_service.close_issue(issue, current_user)
         create_note(issue, commit) if system_note
         notification_service.close_issue(issue, current_user) if notifications

db/migrate/20180209165249_add_closed_by_to_issues.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddClosedByToIssues < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  def change
+    add_column :issues, :closed_by_id, :integer
+  end
+end

lib/api/entities.rb

@@ -407,6 +407,7 @@ module API
 
     class IssueBasic < ProjectEntity
       expose :closed_at
+      expose :closed_by, using: Entities::UserBasic
       expose :labels do |issue, options|
         # Avoids an N+1 query since labels are preloaded
         issue.labels.map(&:title).sort