Unify direct and caching RuleStores in ruler

Instead of using two different `RuleStore` implementations within the Ruler,
use a single caching implementation and selectively disable caching when
required.

This change removes the "direct" `RuleStore` implementation from the Ruler's
gRPC and HTTP API layers. Instead, the caching implementation is used for all
calls. In cases where caching returning stale results would not be acceptable,
the caching is disabled _just_ for that call.

This allows rule group contents to be safety cached with the understanding
that it is safe to cache them because they will correctly invalidated when
deleted or modified.

Part of #9386

development/mimir-microservices-mode/docker-compose.jsonnet

@@ -294,7 +294,7 @@ std.manifestYamlDoc({
 
   memcached:: {
     memcached: {
-      image: 'memcached:1.6.19-alpine',
+      image: 'memcached:1.6.28-alpine',
       ports: [
         '11211:11211',
       ],
@@ -303,7 +303,7 @@ std.manifestYamlDoc({
 
   memcached_exporter:: {
     'memcached-exporter': {
-      image: 'prom/memcached-exporter:v0.6.0',
+      image: 'prom/memcached-exporter:v0.14.4',
       command: ['--memcached.address=memcached:11211', '--web.listen-address=0.0.0.0:9150'],
     },
   },

development/mimir-microservices-mode/docker-compose.yml

@@ -275,14 +275,14 @@
     "ports":
       - "9900:9900"
   "memcached":
-    "image": "memcached:1.6.19-alpine"
+    "image": "memcached:1.6.28-alpine"
     "ports":
       - "11211:11211"
   "memcached-exporter":
     "command":
       - "--memcached.address=memcached:11211"
       - "--web.listen-address=0.0.0.0:9150"
-    "image": "prom/memcached-exporter:v0.6.0"
+    "image": "prom/memcached-exporter:v0.14.4"
   "minio":
     "command":
       - "server"

pkg/mimir/mimir.go

@@ -723,8 +723,7 @@ type Mimir struct {
 	QueryFrontendTopicOffsetsReader *ingest.TopicOffsetsReader
 	QueryFrontendCodec              querymiddleware.Codec
 	Ruler                           *ruler.Ruler
-	RulerDirectStorage              rulestore.RuleStore
-	RulerCachedStorage              rulestore.RuleStore
+	RulerStorage                    rulestore.RuleStore
 	Alertmanager                    *alertmanager.MultitenantAlertmanager
 	Compactor                       *compactor.MultitenantCompactor
 	StoreGateway                    *storegateway.StoreGateway

pkg/mimir/modules.go

@@ -830,13 +830,12 @@ func (t *Mimir) initRulerStorage() (serv services.Service, err error) {
 	// we do accept stale data for about a polling interval (2 intervals in the worst
 	// case scenario due to the jitter applied).
 	cacheTTL := t.Cfg.Ruler.PollInterval
-
-	t.RulerDirectStorage, t.RulerCachedStorage, err = ruler.NewRuleStore(context.Background(), t.Cfg.RulerStorage, t.Overrides, rules.FileLoader{}, cacheTTL, util_log.Logger, t.Registerer)
+	t.RulerStorage, err = ruler.NewRuleStore(context.Background(), t.Cfg.RulerStorage, t.Overrides, rules.FileLoader{}, cacheTTL, util_log.Logger, t.Registerer)
 	return
 }
 
 func (t *Mimir) initRuler() (serv services.Service, err error) {
-	if t.RulerDirectStorage == nil {
+	if t.RulerStorage == nil {
 		level.Info(util_log.Logger).Log("msg", "The ruler storage has not been configured. Not starting the ruler.")
 		return nil, nil
 	}
@@ -939,8 +938,7 @@ func (t *Mimir) initRuler() (serv services.Service, err error) {
 		manager,
 		t.Registerer,
 		util_log.Logger,
-		t.RulerDirectStorage,
-		t.RulerCachedStorage,
+		t.RulerStorage,
 		t.Overrides,
 	)
 	if err != nil {
@@ -951,7 +949,7 @@ func (t *Mimir) initRuler() (serv services.Service, err error) {
 	t.API.RegisterRuler(t.Ruler)
 
 	// Expose HTTP configuration and prometheus-compatible Ruler APIs
-	t.API.RegisterRulerAPI(ruler.NewAPI(t.Ruler, t.RulerDirectStorage, util_log.Logger), t.Cfg.Ruler.EnableAPI, t.BuildInfoHandler)
+	t.API.RegisterRulerAPI(ruler.NewAPI(t.Ruler, t.RulerStorage, util_log.Logger), t.Cfg.Ruler.EnableAPI, t.BuildInfoHandler)
 
 	return t.Ruler, nil
 }

pkg/mimir/modules_test.go

@@ -159,11 +159,9 @@ func TestMimir_InitRulerStorage(t *testing.T) {
 			require.NoError(t, err)
 
 			if testData.expectedInit {
-				assert.NotNil(t, mimir.RulerDirectStorage)
-				assert.NotNil(t, mimir.RulerCachedStorage)
+				assert.NotNil(t, mimir.RulerStorage)
 			} else {
-				assert.Nil(t, mimir.RulerDirectStorage)
-				assert.Nil(t, mimir.RulerCachedStorage)
+				assert.Nil(t, mimir.RulerStorage)
 			}
 		})
 	}

pkg/ruler/api.go

@@ -473,7 +473,9 @@ func (a *API) ListRules(w http.ResponseWriter, req *http.Request) {
 	}
 
 	level.Debug(logger).Log("msg", "retrieving rule groups with namespace", "userID", userID, "namespace", namespace)
-	rgs, err := a.store.ListRuleGroupsForUserAndNamespace(ctx, userID, namespace)
+	// Disable any caching when getting list of all rule groups since listing results
+	// are cached and not invalidated and this API is expected to be strongly consistent.
+	rgs, err := a.store.ListRuleGroupsForUserAndNamespace(ctx, userID, namespace, rulestore.WithCacheDisabled())
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
@@ -606,7 +608,9 @@ func (a *API) CreateRuleGroup(w http.ResponseWriter, req *http.Request) {
 
 	// Only list rule groups when enforcing a max number of groups for this tenant and namespace.
 	if a.ruler.IsMaxRuleGroupsLimited(userID, namespace) {
-		rgs, err := a.store.ListRuleGroupsForUserAndNamespace(ctx, userID, "")
+		// Disable any caching when getting list of all rule groups since listing results
+		// are cached and not invalidated and we need the most up-to-date number.
+		rgs, err := a.store.ListRuleGroupsForUserAndNamespace(ctx, userID, "", rulestore.WithCacheDisabled())
 		if err != nil {
 			level.Error(logger).Log("msg", "unable to fetch current rule groups for validation", "err", err.Error(), "user", userID)
 			http.Error(w, err.Error(), http.StatusInternalServerError)

pkg/ruler/api_test.go

@@ -163,7 +163,7 @@ func TestRuler_ListRules(t *testing.T) {
 			store.setMissingRuleGroups(tc.missingRules)
 
 			r := prepareRuler(t, cfg, store, withStart())
-			a := NewAPI(r, r.directStore, log.NewNopLogger())
+			a := NewAPI(r, r.store, log.NewNopLogger())
 
 			router := mux.NewRouter()
 			router.Path("/prometheus/config/v1/rules").Methods("GET").HandlerFunc(a.ListRules)
@@ -936,7 +936,7 @@ func TestRuler_PrometheusRules(t *testing.T) {
 				return len(rls.Groups)
 			})
 
-			a := NewAPI(r, r.directStore, log.NewNopLogger())
+			a := NewAPI(r, r.store, log.NewNopLogger())
 
 			req := requestFor(t, http.MethodGet, "https://localhost:8080/prometheus/api/v1/rules"+tc.queryParams, nil, userID)
 			w := httptest.NewRecorder()
@@ -993,7 +993,7 @@ func TestRuler_PrometheusAlerts(t *testing.T) {
 		return len(rls.Groups)
 	})
 
-	a := NewAPI(r, r.directStore, log.NewNopLogger())
+	a := NewAPI(r, r.store, log.NewNopLogger())
 
 	req := requestFor(t, http.MethodGet, "https://localhost:8080/prometheus/api/v1/alerts", nil, "user1")
 	w := httptest.NewRecorder()
@@ -1172,7 +1172,7 @@ rules:
 
 			reg := prometheus.NewPedanticRegistry()
 			r := prepareRuler(t, rulerCfg, newMockRuleStore(make(map[string]rulespb.RuleGroupList)), withStart(), withRulerAddrAutomaticMapping(), withPrometheusRegisterer(reg))
-			a := NewAPI(r, r.directStore, log.NewNopLogger())
+			a := NewAPI(r, r.store, log.NewNopLogger())
 
 			router := mux.NewRouter()
 			router.Path("/prometheus/config/v1/rules/{namespace}").Methods("POST").HandlerFunc(a.CreateRuleGroup)
@@ -1237,7 +1237,7 @@ func TestAPI_DeleteNamespace(t *testing.T) {
 
 	reg := prometheus.NewPedanticRegistry()
 	r := prepareRuler(t, cfg, newMockRuleStore(mockRulesNamespaces), withStart(), withRulerAddrAutomaticMapping(), withPrometheusRegisterer(reg))
-	a := NewAPI(r, r.directStore, log.NewNopLogger())
+	a := NewAPI(r, r.store, log.NewNopLogger())
 
 	router := mux.NewRouter()
 	router.Path("/prometheus/config/v1/rules/{namespace}").Methods(http.MethodDelete).HandlerFunc(a.DeleteNamespace)
@@ -1294,7 +1294,7 @@ func TestAPI_DeleteRuleGroup(t *testing.T) {
 
 	reg := prometheus.NewPedanticRegistry()
 	r := prepareRuler(t, cfg, newMockRuleStore(mockRulesNamespaces), withStart(), withRulerAddrAutomaticMapping(), withPrometheusRegisterer(reg))
-	a := NewAPI(r, r.directStore, log.NewNopLogger())
+	a := NewAPI(r, r.store, log.NewNopLogger())
 
 	router := mux.NewRouter()
 	router.Path("/prometheus/config/v1/rules/{namespace}/{groupName}").Methods(http.MethodDelete).HandlerFunc(a.DeleteRuleGroup)
@@ -1336,7 +1336,7 @@ func TestRuler_LimitsPerGroup(t *testing.T) {
 		defaults.RulerMaxRulesPerRuleGroup = 1
 	})))
 
-	a := NewAPI(r, r.directStore, log.NewNopLogger())
+	a := NewAPI(r, r.store, log.NewNopLogger())
 
 	tc := []struct {
 		name   string
@@ -1389,7 +1389,7 @@ func TestRuler_RulerGroupLimits(t *testing.T) {
 		defaults.RulerMaxRulesPerRuleGroup = 1
 	})))
 
-	a := NewAPI(r, r.directStore, log.NewNopLogger())
+	a := NewAPI(r, r.store, log.NewNopLogger())
 
 	tc := []struct {
 		name   string
@@ -1449,7 +1449,7 @@ func TestRuler_RulerGroupLimitsDisabled(t *testing.T) {
 		defaults.RulerMaxRulesPerRuleGroup = 0
 	})))
 
-	a := NewAPI(r, r.directStore, log.NewNopLogger())
+	a := NewAPI(r, r.store, log.NewNopLogger())
 
 	tc := []struct {
 		name   string
@@ -1551,7 +1551,7 @@ func TestAPIRoutesCorrectlyHandleInvalidOrgID(t *testing.T) {
 
 		r := prepareRuler(t, cfg, newMockRuleStore(map[string]rulespb.RuleGroupList{}), withStart())
 
-		a := NewAPI(r, r.directStore, log.NewNopLogger())
+		a := NewAPI(r, r.store, log.NewNopLogger())
 
 		router := mux.NewRouter()
 		router.Path("/api/v1/rules").Methods(http.MethodGet).HandlerFunc(a.PrometheusRules)

pkg/ruler/ruler.go

@@ -38,7 +38,6 @@ import (
 	"github.com/grafana/mimir/pkg/mimirpb"
 	"github.com/grafana/mimir/pkg/ruler/rulespb"
 	"github.com/grafana/mimir/pkg/ruler/rulestore"
-	"github.com/grafana/mimir/pkg/storage/tsdb/bucketcache"
 	"github.com/grafana/mimir/pkg/util"
 	"github.com/grafana/mimir/pkg/util/grpcencoding/s2"
 	util_log "github.com/grafana/mimir/pkg/util/log"
@@ -314,13 +313,12 @@ type MultiTenantManager interface {
 type Ruler struct {
 	services.Service
 
-	cfg         Config
-	lifecycler  *ring.BasicLifecycler
-	ring        *ring.Ring
-	directStore rulestore.RuleStore
-	cachedStore rulestore.RuleStore
-	manager     MultiTenantManager
-	limits      RulesLimits
+	cfg        Config
+	lifecycler *ring.BasicLifecycler
+	ring       *ring.Ring
+	store      rulestore.RuleStore
+	manager    MultiTenantManager
+	limits     RulesLimits
 
 	metrics *rulerMetrics
 
@@ -346,20 +344,14 @@ type Ruler struct {
 }
 
 // NewRuler creates a new ruler from a distributor and chunk store.
-func NewRuler(cfg Config, manager MultiTenantManager, reg prometheus.Registerer, logger log.Logger, directStore, cachedStore rulestore.RuleStore, limits RulesLimits) (*Ruler, error) {
-	// If the cached store is not configured, just fallback to the direct one.
-	if cachedStore == nil {
-		cachedStore = directStore
-	}
-
-	return newRuler(cfg, manager, reg, logger, directStore, cachedStore, limits, newRulerClientPool(cfg.ClientTLSConfig, logger, reg))
+func NewRuler(cfg Config, manager MultiTenantManager, reg prometheus.Registerer, logger log.Logger, store rulestore.RuleStore, limits RulesLimits) (*Ruler, error) {
+	return newRuler(cfg, manager, reg, logger, store, limits, newRulerClientPool(cfg.ClientTLSConfig, logger, reg))
 }
 
-func newRuler(cfg Config, manager MultiTenantManager, reg prometheus.Registerer, logger log.Logger, directStore, cachedStore rulestore.RuleStore, limits RulesLimits, clientPool ClientsPool) (*Ruler, error) {
+func newRuler(cfg Config, manager MultiTenantManager, reg prometheus.Registerer, logger log.Logger, store rulestore.RuleStore, limits RulesLimits, clientPool ClientsPool) (*Ruler, error) {
 	ruler := &Ruler{
 		cfg:               cfg,
-		directStore:       directStore,
-		cachedStore:       cachedStore,
+		store:             store,
 		manager:           manager,
 		registry:          reg,
 		logger:            logger,
@@ -633,7 +625,7 @@ func (r *Ruler) syncRules(ctx context.Context, userIDs []string, reason rulesSyn
 func (r *Ruler) loadRuleGroupsToSync(ctx context.Context, configs map[string]rulespb.RuleGroupList) (map[string]rulespb.RuleGroupList, error) {
 	// Load rule groups.
 	start := time.Now()
-	missing, err := r.directStore.LoadRuleGroups(ctx, configs)
+	missing, err := r.store.LoadRuleGroups(ctx, configs)
 	r.metrics.loadRuleGroups.Observe(time.Since(start).Seconds())
 
 	if err != nil {
@@ -660,7 +652,12 @@ func (r *Ruler) listRuleGroupsToSyncForAllUsers(ctx context.Context, reason rule
 
 	// In order to reduce API calls to the object storage among all ruler replicas,
 	// we support lookup of stale data for a short period.
-	users, err := r.cachedStore.ListAllUsers(bucketcache.WithCacheLookupEnabled(ctx, cacheLookupEnabled))
+	var opts []rulestore.Option
+	if !cacheLookupEnabled {
+		opts = append(opts, rulestore.WithCacheDisabled())
+	}
+
+	users, err := r.store.ListAllUsers(ctx, opts...)
 	if err != nil {
 		return nil, errors.Wrap(err, "unable to list users of ruler")
 	}
@@ -711,11 +708,16 @@ func (r *Ruler) listRuleGroupsToSyncForUsers(ctx context.Context, userIDs []stri
 		concurrency = len(userRings)
 	}
 
+	var opts []rulestore.Option
+	if !cacheLookupEnabled {
+		opts = append(opts, rulestore.WithCacheDisabled())
+	}
+
 	g, gctx := errgroup.WithContext(ctx)
 	for i := 0; i < concurrency; i++ {
 		g.Go(func() error {
 			for userID := range userCh {
-				groups, err := r.cachedStore.ListRuleGroupsForUserAndNamespace(bucketcache.WithCacheLookupEnabled(gctx, cacheLookupEnabled), userID, "")
+				groups, err := r.store.ListRuleGroupsForUserAndNamespace(gctx, userID, "", opts...)
 				if err != nil {
 					return errors.Wrapf(err, "failed to fetch rule groups for user %s", userID)
 				}
@@ -1224,7 +1226,7 @@ func (r *Ruler) DeleteTenantConfiguration(w http.ResponseWriter, req *http.Reque
 		return
 	}
 
-	err = r.directStore.DeleteNamespace(req.Context(), userID, "") // Empty namespace = delete all rule groups.
+	err = r.store.DeleteNamespace(req.Context(), userID, "") // Empty namespace = delete all rule groups.
 	if err != nil && !errors.Is(err, rulestore.ErrGroupNamespaceNotFound) {
 		respondServerError(logger, w, err.Error())
 		return
@@ -1238,8 +1240,8 @@ func (r *Ruler) DeleteTenantConfiguration(w http.ResponseWriter, req *http.Reque
 
 func (r *Ruler) ListAllRules(w http.ResponseWriter, req *http.Request) {
 	logger := util_log.WithContext(req.Context(), r.logger)
-
-	userIDs, err := r.directStore.ListAllUsers(req.Context())
+	// Disable caching when getting a list of users since this API is expected to be strongly consistent.
+	userIDs, err := r.store.ListAllUsers(req.Context(), rulestore.WithCacheDisabled())
 	if err != nil {
 		level.Error(logger).Log("msg", errListAllUser, "err", err)
 		http.Error(w, fmt.Sprintf("%s: %s", errListAllUser, err.Error()), http.StatusInternalServerError)
@@ -1255,12 +1257,14 @@ func (r *Ruler) ListAllRules(w http.ResponseWriter, req *http.Request) {
 	}()
 
 	err = concurrency.ForEachUser(req.Context(), userIDs, fetchRulesConcurrency, func(ctx context.Context, userID string) error {
-		rg, err := r.directStore.ListRuleGroupsForUserAndNamespace(ctx, userID, "")
+		// Disable any caching when getting list of all rule groups since listing results
+		// are cached and not invalidated and this API is expected to be strongly consistent.
+		rg, err := r.store.ListRuleGroupsForUserAndNamespace(ctx, userID, "", rulestore.WithCacheDisabled())
 		if err != nil {
 			return errors.Wrapf(err, "failed to fetch ruler config for user %s", userID)
 		}
 		userRules := map[string]rulespb.RuleGroupList{userID: rg}
-		if missing, err := r.directStore.LoadRuleGroups(ctx, userRules); err != nil {
+		if missing, err := r.store.LoadRuleGroups(ctx, userRules); err != nil {
 			return errors.Wrapf(err, "failed to load ruler config for user %s", userID)
 		} else if len(missing) > 0 {
 			// This API is expected to be strongly consistent, so it's an error if any rule group was missing.

pkg/ruler/ruler_test.go

@@ -54,12 +54,12 @@ import (
 	"github.com/grafana/mimir/pkg/storage/bucket"
 	"github.com/grafana/mimir/pkg/storage/bucket/filesystem"
 	"github.com/grafana/mimir/pkg/util"
-	util_test "github.com/grafana/mimir/pkg/util/test"
+	utiltest "github.com/grafana/mimir/pkg/util/test"
 	"github.com/grafana/mimir/pkg/util/validation"
 )
 
 func TestMain(m *testing.M) {
-	util_test.VerifyNoLeakTestMain(m)
+	utiltest.VerifyNoLeakTestMain(m)
 }
 
 func defaultRulerConfig(t testing.TB) Config {
@@ -210,7 +210,7 @@ func prepareRuler(t *testing.T, cfg Config, storage rulestore.RuleStore, opts ..
 	options := applyPrepareOptions(t, cfg.Ring.Common.InstanceID, opts...)
 	manager := prepareRulerManager(t, cfg, opts...)
 
-	ruler, err := newRuler(cfg, manager, options.registerer, options.logger, storage, storage, options.limits, newMockClientsPool(cfg, options.logger, options.registerer, options.rulerAddrMap))
+	ruler, err := newRuler(cfg, manager, options.registerer, options.logger, storage, options.limits, newMockClientsPool(cfg, options.logger, options.registerer, options.rulerAddrMap))
 	require.NoError(t, err)
 
 	if options.rulerAddrAutoMap {
@@ -1571,7 +1571,7 @@ func verifyExpectedDeletedRuleGroupsForUser(t *testing.T, r *Ruler, userID strin
 	ctx := context.Background()
 
 	t.Run("ListRuleGroupsForUserAndNamespace()", func(t *testing.T) {
-		list, err := r.directStore.ListRuleGroupsForUserAndNamespace(ctx, userID, "")
+		list, err := r.store.ListRuleGroupsForUserAndNamespace(ctx, userID, "")
 		require.NoError(t, err)
 
 		if expectedDeleted {