Revert "Merge branch 'mg-cleanup-redis-cluster-sessions-migration-helper' into 'master'"

This reverts merge request !181631

config/feature_flags/gitlab_com_derisk/use_primary_and_secondary_stores_for_sessions.yml

+---
+name: use_primary_and_secondary_stores_for_sessions
+feature_issue_url: https://gitlab.com/gitlab-com/gl-infra/data-access/durability/team/-/issues/28
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/175735
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/509337
+milestone: '17.9'
+group: group::durability
+type: gitlab_com_derisk
+default_enabled: false

config/feature_flags/gitlab_com_derisk/use_primary_store_as_default_for_sessions.yml

+---
+name: use_primary_store_as_default_for_sessions
+feature_issue_url: https://gitlab.com/gitlab-com/gl-infra/data-access/durability/team/-/issues/28
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/175735
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/509338
+milestone: '17.9'
+group: group::durability
+type: gitlab_com_derisk
+default_enabled: false

lib/gitlab/redis.rb

@@ -10,6 +10,7 @@ module Redis
     ALL_CLASSES = [
       Gitlab::Redis::BufferedCounter,
       Gitlab::Redis::Cache,
+      Gitlab::Redis::ClusterSessions,
       Gitlab::Redis::DbLoadBalancing,
       Gitlab::Redis::FeatureFlag,
       *Gitlab::Redis::Queues.instances.values, # dynamically adds QueueShard* classes

lib/gitlab/redis/cluster_sessions.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Redis
+    class ClusterSessions < ::Gitlab::Redis::Wrapper
+      class << self
+        # The data we store on Sessions used to be stored on SharedState.
+        def config_fallback
+          SharedState
+        end
+      end
+    end
+  end
+end

lib/gitlab/redis/sessions.rb

@@ -2,7 +2,7 @@
 
 module Gitlab
   module Redis
-    class Sessions < ::Gitlab::Redis::Wrapper
+    class Sessions < ::Gitlab::Redis::MultiStoreWrapper
       SESSION_NAMESPACE = 'session:gitlab'
       USER_SESSIONS_NAMESPACE = 'session:user:gitlab'
       USER_SESSIONS_LOOKUP_NAMESPACE = 'session:lookup:user:gitlab'
@@ -13,6 +13,10 @@ class Sessions < ::Gitlab::Redis::Wrapper
       def self.config_fallback
         SharedState
       end
+
+      def self.multistore
+        MultiStore.create_using_pool(ClusterSessions.pool, pool, store_name)
+      end
     end
   end
 end

spec/lib/gitlab/redis/cluster_sessions_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Redis::ClusterSessions, feature_category: :scalability do
+  include_examples "redis_new_instance_shared_examples", 'cluster_sessions', Gitlab::Redis::SharedState
+end

spec/lib/gitlab/redis/sessions_spec.rb

@@ -3,6 +3,7 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::Redis::Sessions, feature_category: :shared do
+  include_examples "multi_store_wrapper_shared_examples"
   include_examples "redis_new_instance_shared_examples", 'sessions', Gitlab::Redis::SharedState
 
   describe '#store' do
@@ -13,4 +14,9 @@
       expect([::Redis::Store, ::Gitlab::Redis::ClusterStore].include?(store.class)).to eq(true)
     end
   end
+
+  it 'migrates from self to ClusterSessions' do
+    expect(described_class.multistore.secondary_pool).to eq(described_class.pool)
+    expect(described_class.multistore.primary_pool).to eq(Gitlab::Redis::ClusterSessions.pool)
+  end
 end