Move Sidekiq exporter logs to log/sidekiq_exporter.log

The Sidekiq exporter logs were mixing with the normal Sidekiq logs. In order
to support structured logging in Sidekiq, we either need to split this data
out or convert the exporter to produce structured logs. Since Sidekiq job
processing is fundamentally different information from Web server traffic,
it seems cleaner to move the metrics traffic into a separate file, where they
can be parsed by a different filter if needed.

Relates to #20060

1 files changed, 9 insertions, 1 deletions

diff --git a/lib/gitlab/metrics/sidekiq_metrics_exporter.rb b/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
index db8bdde74b2..47b4af5d649 100644
--- a/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
+++ b/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
@@ -4,6 +4,8 @@ require 'prometheus/client/rack/exporter'
 module Gitlab
   module Metrics
     class SidekiqMetricsExporter < Daemon
+      LOG_FILENAME = File.join(Rails.root, 'log', 'sidekiq_exporter.log')
+
       def enabled?
         Gitlab::Metrics.metrics_folder_present? && settings.enabled
       end
@@ -17,7 +19,13 @@ module Gitlab
       attr_reader :server
 
       def start_working
-        @server = ::WEBrick::HTTPServer.new(Port: settings.port, BindAddress: settings.address)
+        logger = WEBrick::Log.new(LOG_FILENAME)
+        access_log = [
+          [logger, WEBrick::AccessLog::COMBINED_LOG_FORMAT]
+        ]
+
+        @server = ::WEBrick::HTTPServer.new(Port: settings.port, BindAddress: settings.address,
+                                            Logger: logger, AccessLog: access_log)
         server.mount "/", Rack::Handler::WEBrick, rack_app
         server.start
       end