Initialize redis stoer and use it for session_store

- Add specs and ENV variable

config/initializers/session_store.rb

@@ -18,16 +18,33 @@ cookie_key = if Rails.env.development?
              else
                "_gitlab_session"
              end
+if Gitlab::Utils.to_boolean(ENV['GITLAB_LEGACY_SESSION_STORE'], default: false)
+  sessions_config = Gitlab::Redis::SharedState.params
+  sessions_config[:namespace] = Gitlab::Redis::SharedState::SESSION_NAMESPACE
+
+
+  Gitlab::Application.config.session_store(
+    :redis_store, # Using the cookie_store would enable session replay attacks.
+    servers: sessions_config,
+    key: cookie_key,
+    secure: Gitlab.config.gitlab.https,
+    httponly: true,
+    expires_in: Settings.gitlab['session_expire_delay'] * 60,
+    path: Rails.application.config.relative_url_root.presence || '/'
+  )
+else
+  store = Gitlab::Redis::SharedState.store(
+    namespace: Gitlab::Redis::SharedState::SESSION_NAMESPACE
+  )
+
+  Gitlab::Application.config.session_store(
+    :redis_store, # Using the cookie_store would enable session replay attacks.
+    redis_store: store,
+    key: cookie_key,
+    expires_in: Settings.gitlab['session_expire_delay'] * 60,
+    httponly: true,
+    secure: Gitlab.config.gitlab.https
+  )
+end
+
 
-sessions_config = Gitlab::Redis::SharedState.params
-sessions_config[:namespace] = Gitlab::Redis::SharedState::SESSION_NAMESPACE
-
-Gitlab::Application.config.session_store(
-  :redis_store, # Using the cookie_store would enable session replay attacks.
-  servers: sessions_config,
-  key: cookie_key,
-  secure: Gitlab.config.gitlab.https,
-  httponly: true,
-  expires_in: Settings.gitlab['session_expire_delay'] * 60,
-  path: Rails.application.config.relative_url_root.presence || '/'
-)

lib/gitlab/redis/wrapper.rb

@@ -17,7 +17,7 @@ module Gitlab
   module Redis
     class Wrapper
       class << self
-        delegate :params, :url, to: :new
+        delegate :params, :url, :store, to: :new
 
         def with
           pool.with { |redis| yield redis }
@@ -126,6 +126,10 @@ module Gitlab
         sentinels && !sentinels.empty?
       end
 
+      def store(extras = {})
+        ::Redis::Store::Factory.create(redis_store_options.merge(extras))
+      end
+
       private
 
       def redis_store_options

spec/initializers/session_store_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Session initializer for GitLab' do
+  subject { Gitlab::Application.config }
+
+  let(:load_session_store) do
+    load Rails.root.join('config/initializers/session_store.rb')
+  end
+
+  describe 'config#session_store' do
+    context 'when the GITLAB_LEGACY_SESSION_STORE env is enabled' do
+      before do
+        stub_env('GITLAB_LEGACY_SESSION_STORE', true)
+      end
+
+      it 'returns the regular cookie without a suffix' do
+        expect(subject).to receive(:session_store).with(:redis_store, a_hash_including(servers: kind_of(Hash)))
+
+        load_session_store
+      end
+
+    end
+
+    context 'when the GITLAB_LEGACY_SESSION_STORE env is not set' do
+      before do
+        stub_env('GITLAB_LEGACY_SESSION_STORE', nil)
+      end
+
+      it 'returns the regular cookie without a suffix' do
+        expect(subject).to receive(:session_store).with(:redis_store, a_hash_including(redis_store: kind_of(::Redis::Store)))
+
+        load_session_store
+      end
+    end
+  end
+end

spec/support/redis/redis_shared_examples.rb

@@ -87,6 +87,43 @@ RSpec.shared_examples "redis_shared_examples" do
     end
   end
 
+  describe '.store' do
+    let(:rails_env) { 'development' }
+
+    subject { described_class.new(rails_env).store }
+
+    shared_examples 'redis store' do
+      it 'instantiates Redis::Store' do
+        is_expected.to be_a(::Redis::Store)
+        expect(subject.to_s).to eq("Redis Client connected to #{host} against DB #{redis_database}")
+      end
+
+      context 'with the namespace' do
+        let(:namespace) { 'namespace_name' }
+
+        subject { described_class.new(rails_env).store(namespace: namespace) }
+
+        it "uses specified namespace" do
+          expect(subject.to_s).to eq("Redis Client connected to #{host} against DB #{redis_database} with namespace #{namespace}")
+        end
+      end
+    end
+
+    context 'with old format' do
+      it_behaves_like 'redis store' do
+        let(:config_file_name) { config_old_format_host }
+        let(:host) { "localhost:#{redis_port}" }
+      end
+    end
+
+    context 'with new format' do
+      it_behaves_like 'redis store' do
+        let(:config_file_name) { config_new_format_host }
+        let(:host) { "development-host:#{redis_port}" }
+      end
+    end
+  end
+
   describe '.params' do
     subject { described_class.new(rails_env).params }