distributor: allow skipping label count validation

CHANGELOG.md

@@ -27,6 +27,7 @@
 * [FEATURE] Alertmanager: limit added for maximum size of the Grafana state (`-alertmanager.max-grafana-state-size-bytes`). #9475
 * [FEATURE] Alertmanager: limit added for maximum size of the Grafana configuration (`-alertmanager.max-config-size-bytes`). #9402
 * [FEATURE] Ingester: Experimental support for ingesting out-of-order native histograms. This is disabled by default and can be enabled by setting `-ingester.ooo-native-histograms-ingestion-enabled` to `true`. #7175
+* [FEATURE] Distributor: Added `-api.skip-label-count-validation-header-enabled` option to allow skipping label count validation on the HTTP write path based on `X-Mimir-SkipLabelCountValidation` header being `true` or not. #9576
 * [ENHANCEMENT] mimirtool: Adds bearer token support for mimirtool's analyze ruler/prometheus commands. #9587
 * [ENHANCEMENT] Ruler: Support `exclude_alerts` parameter in `<prometheus-http-prefix>/api/v1/rules` endpoint. #9300
 * [ENHANCEMENT] Distributor: add a metric to track tenants who are sending newlines in their label values called `cortex_distributor_label_values_with_newlines_total`. #9400

cmd/mimir/config-descriptor.json

@@ -85,6 +85,17 @@
           "fieldType": "boolean",
           "fieldCategory": "advanced"
         },
+        {
+          "kind": "field",
+          "name": "skip_label_count_validation_header_enabled",
+          "required": false,
+          "desc": "Allows to disable enforcement of the label count limit \"max_label_names_per_series\" via X-Mimir-SkipLabelCountValidation header on the http write path. Allowing this for external clients allows any client to send invalid label counts. After enabling it, requests with a specific HTTP header set to true will not have label counts validated.",
+          "fieldValue": null,
+          "fieldDefaultValue": false,
+          "fieldFlag": "api.skip-label-count-validation-header-enabled",
+          "fieldType": "boolean",
+          "fieldCategory": "advanced"
+        },
         {
           "kind": "field",
           "name": "get_request_for_ingester_shutdown_enabled",

cmd/mimir/help-all.txt.tmpl

@@ -313,6 +313,8 @@ Usage of ./cmd/mimir/mimir:
     	The URL under which Alertmanager is externally reachable (eg. could be different than -http.alertmanager-http-prefix in case Alertmanager is served via a reverse proxy). This setting is used both to configure the internal requests router and to generate links in alert templates. If the external URL has a path portion, it will be used to prefix all HTTP endpoints served by Alertmanager, both the UI and API. (default http://localhost:8080/alertmanager)
   -api.get-request-for-ingester-shutdown-enabled
     	[deprecated] Enable GET requests to the /ingester/shutdown endpoint to trigger an ingester shutdown. This is a potentially dangerous operation and should only be enabled consciously.
+  -api.skip-label-count-validation-header-enabled
+    	Allows to disable enforcement of the label count limit "max_label_names_per_series" via X-Mimir-SkipLabelCountValidation header on the http write path. Allowing this for external clients allows any client to send invalid label counts. After enabling it, requests with a specific HTTP header set to true will not have label counts validated.
   -api.skip-label-name-validation-header-enabled
     	Allows to skip label name validation via X-Mimir-SkipLabelNameValidation header on the http write path. Use with caution as it breaks PromQL. Allowing this for external clients allows any client to send invalid label names. After enabling it, requests with a specific HTTP header set to true will not have label names validated.
   -auth.multitenancy-enabled

docs/sources/mimir/configure/configuration-parameters/index.md

@@ -141,6 +141,14 @@ api:
   # CLI flag: -api.skip-label-name-validation-header-enabled
   [skip_label_name_validation_header_enabled: <boolean> | default = false]
 
+  # (advanced) Allows to disable enforcement of the label count limit
+  # "max_label_names_per_series" via X-Mimir-SkipLabelCountValidation header on
+  # the http write path. Allowing this for external clients allows any client to
+  # send invalid label counts. After enabling it, requests with a specific HTTP
+  # header set to true will not have label counts validated.
+  # CLI flag: -api.skip-label-count-validation-header-enabled
+  [skip_label_count_validation_header_enabled: <boolean> | default = false]
+
   # (deprecated) Enable GET requests to the /ingester/shutdown endpoint to
   # trigger an ingester shutdown. This is a potentially dangerous operation and
   # should only be enabled consciously.

pkg/api/api.go

@@ -48,7 +48,8 @@ import (
 type ConfigHandler func(actualCfg interface{}, defaultCfg interface{}) http.HandlerFunc
 
 type Config struct {
-	SkipLabelNameValidationHeader bool `yaml:"skip_label_name_validation_header_enabled" category:"advanced"`
+	SkipLabelNameValidationHeader  bool `yaml:"skip_label_name_validation_header_enabled" category:"advanced"`
+	SkipLabelCountValidationHeader bool `yaml:"skip_label_count_validation_header_enabled" category:"advanced"`
 
 	// TODO: Remove option in Mimir 2.15.
 	GETRequestForIngesterShutdownEnabled bool `yaml:"get_request_for_ingester_shutdown_enabled" category:"deprecated"`
@@ -70,6 +71,7 @@ type Config struct {
 // RegisterFlags adds the flags required to config this to the given FlagSet.
 func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.BoolVar(&cfg.SkipLabelNameValidationHeader, "api.skip-label-name-validation-header-enabled", false, "Allows to skip label name validation via X-Mimir-SkipLabelNameValidation header on the http write path. Use with caution as it breaks PromQL. Allowing this for external clients allows any client to send invalid label names. After enabling it, requests with a specific HTTP header set to true will not have label names validated.")
+	f.BoolVar(&cfg.SkipLabelCountValidationHeader, "api.skip-label-count-validation-header-enabled", false, "Allows to disable enforcement of the label count limit \"max_label_names_per_series\" via X-Mimir-SkipLabelCountValidation header on the http write path. Allowing this for external clients allows any client to send invalid label counts. After enabling it, requests with a specific HTTP header set to true will not have label counts validated.")
 	f.BoolVar(&cfg.GETRequestForIngesterShutdownEnabled, "api.get-request-for-ingester-shutdown-enabled", false, "Enable GET requests to the /ingester/shutdown endpoint to trigger an ingester shutdown. This is a potentially dangerous operation and should only be enabled consciously.")
 	cfg.RegisterFlagsWithPrefix("", f)
 }
@@ -262,7 +264,7 @@ const OTLPPushEndpoint = "/otlp/v1/metrics"
 func (a *API) RegisterDistributor(d *distributor.Distributor, pushConfig distributor.Config, reg prometheus.Registerer, limits *validation.Overrides) {
 	distributorpb.RegisterDistributorServer(a.server.GRPC, d)
 
-	a.RegisterRoute(PrometheusPushEndpoint, distributor.Handler(pushConfig.MaxRecvMsgSize, d.RequestBufferPool, a.sourceIPs, a.cfg.SkipLabelNameValidationHeader, limits, pushConfig.RetryConfig, d.PushWithMiddlewares, d.PushMetrics, a.logger), true, false, "POST")
+	a.RegisterRoute(PrometheusPushEndpoint, distributor.Handler(pushConfig.MaxRecvMsgSize, d.RequestBufferPool, a.sourceIPs, a.cfg.SkipLabelNameValidationHeader, a.cfg.SkipLabelCountValidationHeader, limits, pushConfig.RetryConfig, d.PushWithMiddlewares, d.PushMetrics, a.logger), true, false, "POST")
 	a.RegisterRoute(OTLPPushEndpoint, distributor.OTLPHandler(pushConfig.MaxOTLPRequestSize, d.RequestBufferPool, a.sourceIPs, limits, pushConfig.RetryConfig, d.PushWithMiddlewares, d.PushMetrics, reg, a.logger, pushConfig.DirectOTLPTranslationEnabled), true, false, "POST")
 
 	a.indexPage.AddLinks(defaultWeight, "Distributor", []IndexPageLink{

pkg/distributor/distributor.go

@@ -198,10 +198,14 @@ type Config struct {
 	// for testing and for extending the ingester by adding calls to the client
 	IngesterClientFactory ring_client.PoolFactory `yaml:"-"`
 
-	// when true the distributor does not validate the label name and value, Mimir doesn't directly use
-	// this (and should never use it) but this feature is used by other projects built on top of it
+	// When SkipLabelValidation is true the distributor does not validate the label name and value, Mimir doesn't directly use
+	// this (and should never use it) but this feature is used by other projects built on top of it.
 	SkipLabelValidation bool `yaml:"-"`
 
+	// When SkipLabelCountValidation is true the distributor does not validate the number of labels, Mimir doesn't directly use
+	// this (and should never use it) but this feature is used by other projects built on top of it.
+	SkipLabelCountValidation bool `yaml:"-"`
+
 	// This config is dynamically injected because it is defined in the querier config.
 	ShuffleShardingLookbackPeriod              time.Duration `yaml:"-"`
 	StreamingChunksPerIngesterSeriesBufferSize uint64        `yaml:"-"`
@@ -713,8 +717,8 @@ func (d *Distributor) checkSample(ctx context.Context, userID, cluster, replica
 // May alter timeseries data in-place.
 // The returned error may retain the series labels.
 // It uses the passed nowt time to observe the delay of sample timestamps.
-func (d *Distributor) validateSeries(nowt time.Time, ts *mimirpb.PreallocTimeseries, userID, group string, skipLabelValidation bool, minExemplarTS, maxExemplarTS int64) error {
-	if err := validateLabels(d.sampleValidationMetrics, d.limits, userID, group, ts.Labels, skipLabelValidation); err != nil {
+func (d *Distributor) validateSeries(nowt time.Time, ts *mimirpb.PreallocTimeseries, userID, group string, skipLabelValidation, skipLabelCountValidation bool, minExemplarTS, maxExemplarTS int64) error {
+	if err := validateLabels(d.sampleValidationMetrics, d.limits, userID, group, ts.Labels, skipLabelValidation, skipLabelCountValidation); err != nil {
 		return err
 	}
 
@@ -1051,8 +1055,10 @@ func (d *Distributor) prePushValidationMiddleware(next PushFunc) PushFunc {
 			d.labelsHistogram.Observe(float64(len(ts.Labels)))
 
 			skipLabelValidation := d.cfg.SkipLabelValidation || req.GetSkipLabelValidation()
+			skipLabelCountValidation := d.cfg.SkipLabelCountValidation || req.GetSkipLabelCountValidation()
+
 			// Note that validateSeries may drop some data in ts.
-			validationErr := d.validateSeries(now, &req.Timeseries[tsIdx], userID, group, skipLabelValidation, minExemplarTS, maxExemplarTS)
+			validationErr := d.validateSeries(now, &req.Timeseries[tsIdx], userID, group, skipLabelValidation, skipLabelCountValidation, minExemplarTS, maxExemplarTS)
 
 			// Errors in validation are considered non-fatal, as one series in a request may contain
 			// invalid data but all the remaining series could be perfectly valid.

pkg/distributor/distributor_ingest_storage_test.go

@@ -301,7 +301,7 @@ func TestDistributor_Push_ShouldReturnErrorMappedTo4xxStatusCodeIfWriteRequestCo
 		sourceIPs, _ := middleware.NewSourceIPs("SomeField", "(.*)", false)
 
 		// Send write request through the HTTP handler.
-		h := Handler(maxRecvMsgSize, nil, sourceIPs, false, overrides, RetryConfig{}, distributors[0].PushWithMiddlewares, nil, log.NewNopLogger())
+		h := Handler(maxRecvMsgSize, nil, sourceIPs, false, false, overrides, RetryConfig{}, distributors[0].PushWithMiddlewares, nil, log.NewNopLogger())
 		h.ServeHTTP(resp, createRequest(t, marshalledReq))
 		assert.Equal(t, http.StatusBadRequest, resp.Code)
 	})

pkg/distributor/distributor_test.go

@@ -1661,7 +1661,7 @@ func TestDistributor_ExemplarValidation(t *testing.T) {
 			require.Len(t, regs, 1)
 
 			for _, ts := range tc.req.Timeseries {
-				err := ds[0].validateSeries(now, &ts, "user", "test-group", false, tc.minExemplarTS, tc.maxExemplarTS)
+				err := ds[0].validateSeries(now, &ts, "user", "test-group", false, false, tc.minExemplarTS, tc.maxExemplarTS)
 				assert.NoError(t, err)
 			}
 
@@ -1768,7 +1768,7 @@ func TestDistributor_HistogramReduction(t *testing.T) {
 			require.Len(t, regs, 1)
 
 			for _, ts := range tc.req.Timeseries {
-				err := ds[0].validateSeries(now, &ts, "user", "test-group", false, 0, 0)
+				err := ds[0].validateSeries(now, &ts, "user", "test-group", false, false, 0, 0)
 				if tc.expectedError != nil {
 					require.ErrorAs(t, err, &tc.expectedError)
 				} else {

pkg/distributor/push.go

@@ -44,8 +44,10 @@ var (
 )
 
 const (
-	SkipLabelNameValidationHeader = "X-Mimir-SkipLabelNameValidation"
-	statusClientClosedRequest     = 499
+	SkipLabelNameValidationHeader  = "X-Mimir-SkipLabelNameValidation"
+	SkipLabelCountValidationHeader = "X-Mimir-SkipLabelCountValidation"
+
+	statusClientClosedRequest = 499
 )
 
 type RetryConfig struct {
@@ -77,13 +79,14 @@ func Handler(
 	requestBufferPool util.Pool,
 	sourceIPs *middleware.SourceIPExtractor,
 	allowSkipLabelNameValidation bool,
+	allowSkipLabelCountValidation bool,
 	limits *validation.Overrides,
 	retryCfg RetryConfig,
 	push PushFunc,
 	pushMetrics *PushMetrics,
 	logger log.Logger,
 ) http.Handler {
-	return handler(maxRecvMsgSize, requestBufferPool, sourceIPs, allowSkipLabelNameValidation, limits, retryCfg, push, logger, func(ctx context.Context, r *http.Request, maxRecvMsgSize int, buffers *util.RequestBuffers, req *mimirpb.PreallocWriteRequest, _ log.Logger) error {
+	return handler(maxRecvMsgSize, requestBufferPool, sourceIPs, allowSkipLabelNameValidation, allowSkipLabelCountValidation, limits, retryCfg, push, logger, func(ctx context.Context, r *http.Request, maxRecvMsgSize int, buffers *util.RequestBuffers, req *mimirpb.PreallocWriteRequest, _ log.Logger) error {
 		protoBodySize, err := util.ParseProtoReader(ctx, r.Body, int(r.ContentLength), maxRecvMsgSize, buffers, req, util.RawSnappy)
 		if errors.Is(err, util.MsgSizeTooLargeErr{}) {
 			err = distributorMaxWriteMessageSizeErr{actual: int(r.ContentLength), limit: maxRecvMsgSize}
@@ -130,6 +133,7 @@ func handler(
 	requestBufferPool util.Pool,
 	sourceIPs *middleware.SourceIPExtractor,
 	allowSkipLabelNameValidation bool,
+	allowSkipLabelCountValidation bool,
 	limits *validation.Overrides,
 	retryCfg RetryConfig,
 	push PushFunc,
@@ -177,6 +181,12 @@ func handler(
 				req.SkipLabelValidation = false
 			}
 
+			if allowSkipLabelCountValidation {
+				req.SkipLabelCountValidation = req.SkipLabelCountValidation && r.Header.Get(SkipLabelCountValidationHeader) == "true"
+			} else {
+				req.SkipLabelCountValidation = false
+			}
+
 			cleanup := func() {
 				mimirpb.ReuseSlice(req.Timeseries)
 				rb.CleanUp()