Add option to enable Sidekiq Exporter logs

In https://gitlab.com/gitlab-org/gitlab/-/merge_requests/42267, we are
disabling the Sidekiq Exporter logs by default since they are noisy and
don't add a lot of value.  This change allows admins to enable them if
needed.

changelogs/unreleased/sh-add-sidekiq-exporter-log-config.yml

+---
+title: Add option to enable Sidekiq Exporter logs
+merge_request: 4573
+author:
+type: changed

files/gitlab-config-template/gitlab.rb.template

@@ -929,6 +929,7 @@ gitlab_rails['object_store']['objects']['terraform_state']['bucket'] = nil
 # sidekiq['negate'] = false
 # sidekiq['metrics_enabled'] = true
+# sidekiq['exporter_log_enabled'] = false
 # sidekiq['listen_address'] = "localhost"
 # sidekiq['listen_port'] = 8082

files/gitlab-cookbooks/gitlab/attributes/default.rb

@@ -526,6 +526,7 @@ default['gitlab']['sidekiq']['log_format'] = "json"
 default['gitlab']['sidekiq']['shutdown_timeout'] = 25
 default['gitlab']['sidekiq']['concurrency'] = 25
 default['gitlab']['sidekiq']['metrics_enabled'] = true
+default['gitlab']['sidekiq']['exporter_log_enabled'] = false
 # Sidekiq http listener
 default['gitlab']['sidekiq']['listen_address'] = "127.0.0.1"

files/gitlab-cookbooks/gitlab/templates/default/gitlab.yml.erb

@@ -764,6 +764,7 @@ production: &base
     # Sidekiq exporter is webserver built in to Sidekiq to expose Prometheus metrics
     sidekiq_exporter:
       enabled: <%= @sidekiq['metrics_enabled'] %>
+      log_enabled: <%= @sidekiq['exporter_log_enabled'] %>
       address: <%= @sidekiq['listen_address'] %>
       port: <%= @sidekiq['listen_port'] %>

spec/chef/recipes/gitlab-rails_spec.rb

@@ -1785,6 +1785,30 @@ RSpec.describe 'gitlab::gitlab-rails' do
       end
     end
+    context 'Sidekiq exporter settings' do
+      it 'exporter enabled but log disabled by default' do
+        expect(chef_run).to render_file(gitlab_yml_path).with_content { |content|
+          yaml_data = YAML.safe_load(content, [], [], true)
+          expect(yaml_data['production']['monitoring']['sidekiq_exporter']).to include('enabled' => true, 'log_enabled' => false)
+        }
+      end
+
+      context 'when exporter log enabled' do
+        before do
+          stub_gitlab_rb(
+            sidekiq: { exporter_log_enabled: true }
+          )
+        end
+
+        it 'enables the log' do
+          expect(chef_run).to render_file(gitlab_yml_path).with_content { |content|
+            yaml_data = YAML.safe_load(content, [], [], true)
+            expect(yaml_data['production']['monitoring']['sidekiq_exporter']).to include('enabled' => true, 'log_enabled' => true)
+          }
+        end
+      end
+    end
+
     context 'Shutdown settings' do
       context 'Blackout setting' do
         it 'default setting' do