Merge branch 'pages-debug-log' into 'master'

Log errors in UpdatePagesService

See merge request !10335

app/services/base_service.rb

@@ -24,6 +24,10 @@ class BaseService
     Gitlab::AppLogger.info message
   end
 
+  def log_error(message)
+    Gitlab::AppLogger.error message
+  end
+
   def system_hook_service
     SystemHooksService.new
   end

app/services/projects/update_pages_service.rb

@@ -46,6 +46,7 @@ module Projects
     end
 
     def error(message, http_status = nil)
+      log_error("Projects::UpdatePagesService: #{message}")
       @status.allow_failure = !latest?
       @status.description = message
       @status.drop

changelogs/unreleased/pages-debug-log.yml

+---
+title: Log errors during generating of Gitlab Pages to debug log
+merge_request: 10335
+author: Danilo Bargen