1 files changed, 43 insertions, 0 deletions
diff --git a/app/controllers/concerns/impersonation.rb b/app/controllers/concerns/impersonation.rb
new file mode 100644
index 00000000000..a4f2c263eb4
--- /dev/null
+++ b/app/controllers/concerns/impersonation.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Impersonation
+  include Gitlab::Utils::StrongMemoize
+
+  def current_user
+    user = super
+
+    user.impersonator = impersonator if impersonator
+
+    user
+  end
+
+  protected
+
+  def check_impersonation_availability
+    return unless session[:impersonator_id]
+
+    unless Gitlab.config.gitlab.impersonation_enabled
+      stop_impersonation
+      access_denied! _('Impersonation has been disabled')
+    end
+  end
+
+  def stop_impersonation
+    log_impersonation_event
+
+    warden.set_user(impersonator, scope: :user)
+    session[:impersonator_id] = nil
+
+    current_user
+  end
+
+  def log_impersonation_event
+    Gitlab::AppLogger.info("User #{impersonator.username} has stopped impersonating #{current_user.username}")
+  end
+
+  def impersonator
+    strong_memoize(:impersonator) do
+      User.find(session[:impersonator_id]) if session[:impersonator_id]
+    end
+  end
+end