Merge branch 'sc1-lock-migrated-shard' into 'master'

Define SIDEKIQ_MIGRATED_SHARDS for sidekiq shard router

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/150591



Merged-by: Sylvester Chin <schin@gitlab.com>
Approved-by: Bob Van Landuyt <bob@gitlab.com>

config/initializers/sidekiq.rb

@@ -15,6 +15,9 @@ def load_cron_jobs!
   end
 end
 
+# initialise migrated_shards on start-up to catch any malformed SIDEKIQ_MIGRATED_SHARD lists.
+Gitlab::SidekiqSharding::Router.migrated_shards
+
 # Custom Queues configuration
 #
 # We omit :command_builder since Sidekiq::RedisConnection performs a deep clone using

lib/gitlab/sidekiq_sharding/router.rb

@@ -38,11 +38,16 @@ def route(klass)
           end
         end
 
+        def migrated_shards
+          @migrated_shards ||= Set.new(Gitlab::Json.parse(ENV.fetch('SIDEKIQ_MIGRATED_SHARDS', '[]')))
+        end
+
         private
 
         def route_to(shard_name)
           # early return if main since we do not want a redundant feature flag check
           return shard_name if shard_name == Gitlab::Redis::Queues::SIDEKIQ_MAIN_SHARD_INSTANCE_NAME
+          return shard_name if migrated_shards.include?(shard_name)
 
           if shard_name.nil? ||
               Feature.disabled?(:"sidekiq_route_to_#{shard_name}", type: :worker, default_enabled_if_undefined: false)

spec/lib/gitlab/sidekiq_sharding/router_spec.rb

@@ -106,6 +106,25 @@
         end
       end
 
+      context 'when shard is migrated' do
+        before do
+          stub_env('SIDEKIQ_MIGRATED_SHARDS', "[\"queues_shard_test\"]")
+
+          if described_class.instance_variable_defined?(:@migrated_shards)
+            described_class.remove_instance_variable(:@migrated_shards)
+          end
+        end
+
+        it 'returns shard without checking feature flag' do
+          expect(Feature).not_to receive(:enabled?)
+
+          name, redis = get_test_shard
+
+          expect(name).to eq('queues_shard_test')
+          expect(redis).to eq(shard_sidekiq_redis)
+        end
+      end
+
       context 'when feature flag is enabled' do
         before do
           allow(Feature).to receive(:enabled?)