Merge branch 'enable-query-analyzers-in-production' into 'master'

Allow to enable query analyzers in production

See merge request gitlab-org/gitlab!74078

config/initializers/database_query_analyzers.rb

 # frozen_string_literal: true
 
 # Currently we register validator only for `dev` or `test` environment
-Gitlab::Database::QueryAnalyzer.new.hook! if Gitlab.dev_or_test_env?
+if Gitlab.dev_or_test_env? || Gitlab::Utils.to_boolean(ENV['GITLAB_ENABLE_QUERY_ANALYZERS'], default: false)
+  Gitlab::Database::QueryAnalyzer.instance.hook!
+end

lib/gitlab/database/query_analyzer.rb

@@ -5,6 +5,8 @@ module Gitlab
     # The purpose of this class is to implement a various query analyzers based on `pg_query`
     # And process them all via `Gitlab::Database::QueryAnalyzers::*`
     class QueryAnalyzer
+      include ::Singleton
+
       ANALYZERS = [].freeze
 
       Parsed = Struct.new(

spec/lib/gitlab/database/query_analyzer_spec.rb

@@ -65,7 +65,7 @@ RSpec.describe Gitlab::Database::QueryAnalyzer do
 
     def process_sql(sql)
       ApplicationRecord.load_balancer.read_write do |connection|
-        described_class.new.send(:process_sql, sql, connection)
+        described_class.instance.send(:process_sql, sql, connection)
       end
     end
   end