enable virtual read write targets (#4498)

Co-Authored-By: Mauro Stettler <mauro.stettler@gmail.com>

Co-authored-by: Mauro Stettler <mauro.stettler@gmail.com>

pkg/loki/loki.go

@@ -425,7 +425,10 @@ func (t *Loki) setupModuleManager() error {
 	mm.RegisterModule(Compactor, t.initCompactor)
 	mm.RegisterModule(IndexGateway, t.initIndexGateway)
 	mm.RegisterModule(QueryScheduler, t.initQueryScheduler)
+
 	mm.RegisterModule(All, nil)
+	mm.RegisterModule(Read, nil)
+	mm.RegisterModule(Write, nil)
 
 	// Add dependencies
 	deps := map[string][]string{
@@ -446,6 +449,8 @@ func (t *Loki) setupModuleManager() error {
 		IndexGateway:             {Server},
 		IngesterQuerier:          {Ring},
 		All:                      {QueryScheduler, QueryFrontend, Querier, Ingester, Distributor, Ruler},
+		Read:                     {QueryScheduler, QueryFrontend, Querier, Ruler},
+		Write:                    {Ingester, Distributor},
 	}
 
 	// Add IngesterQuerier as a dependency for store when target is either ingester or querier.

pkg/loki/modules.go

@@ -81,6 +81,8 @@ const (
 	IndexGateway             string = "index-gateway"
 	QueryScheduler           string = "query-scheduler"
 	All                      string = "all"
+	Read                     string = "read"
+	Write                    string = "write"
 )
 
 func (t *Loki) initServer() (services.Service, error) {
@@ -194,7 +196,7 @@ func (t *Loki) initDistributor() (services.Service, error) {
 
 	// Register the distributor to receive Push requests over GRPC
 	// EXCEPT when running with `-target=all` or `-target=` contains `ingester`
-	if !t.Cfg.isModuleEnabled(All) && !t.Cfg.isModuleEnabled(Ingester) {
+	if !t.Cfg.isModuleEnabled(All) && !t.Cfg.isModuleEnabled(Write) && !t.Cfg.isModuleEnabled(Ingester) {
 		logproto.RegisterPusherServer(t.Server.GRPC, t.distributor)
 	}
 
@@ -221,6 +223,7 @@ func (t *Loki) initQuerier() (services.Service, error) {
 
 	querierWorkerServiceConfig := querier.WorkerServiceConfig{
 		AllEnabled:            t.Cfg.isModuleEnabled(All),
+		ReadEnabled:           t.Cfg.isModuleEnabled(Read),
 		GrpcListenPort:        t.Cfg.Server.GRPCListenPort,
 		QuerierMaxConcurrent:  t.Cfg.Querier.MaxConcurrent,
 		QuerierWorkerConfig:   &t.Cfg.Worker,

pkg/querier/worker_service.go

@@ -21,6 +21,7 @@ import (
 
 type WorkerServiceConfig struct {
 	AllEnabled            bool
+	ReadEnabled           bool
 	GrpcListenPort        int
 	QuerierMaxConcurrent  int
 	QuerierWorkerConfig   *querier_worker.Config
@@ -144,12 +145,13 @@ func registerRoutesExternally(routes []string, externalRouter *mux.Router, inter
 }
 
 func querierRunningStandalone(cfg WorkerServiceConfig) bool {
-	runningStandalone := !cfg.QueryFrontendEnabled && !cfg.QuerySchedulerEnabled && !cfg.AllEnabled
+	runningStandalone := !cfg.QueryFrontendEnabled && !cfg.QuerySchedulerEnabled && !cfg.ReadEnabled && !cfg.AllEnabled
 	level.Debug(util_log.Logger).Log(
 		"msg", "determining if querier is running as standalone target",
 		"runningStandalone", runningStandalone,
 		"queryFrontendEnabled", cfg.QueryFrontendEnabled,
 		"queryScheduleEnabled", cfg.QuerySchedulerEnabled,
+		"readEnabled", cfg.ReadEnabled,
 		"allEnabled", cfg.AllEnabled,
 	)