Tsdb/index sampling endpoint (#6347)

* index sampling endpoint

* fix bug in withTenantLabelMatcher

* show zero values in stats

* handles new errcase

* fixes comments

docs/sources/api/_index.md

@@ -28,6 +28,8 @@ These endpoints are exposed by the querier and the query frontend:
 - [`GET /loki/api/v1/query_range`](#get-lokiapiv1query_range)
 - [`GET /loki/api/v1/labels`](#get-lokiapiv1labels)
 - [`GET /loki/api/v1/label/<name>/values`](#get-lokiapiv1labelnamevalues)
+- [`GET /loki/api/v1/series`](#series)
+- [`GET /loki/api/v1/index/stats`](#index-stats)
 - [`GET /loki/api/v1/tail`](#get-lokiapiv1tail)
 - [`POST /loki/api/v1/push`](#post-lokiapiv1push)
 - [`GET /ready`](#get-ready)
@@ -920,6 +922,38 @@ $ curl -s "http://localhost:3100/loki/api/v1/series" --data-urlencode 'match[]={
 }
 ```
 
+
+## Index Stats
+
+The `/loki/api/v1/index/stats` endpoint can be used to query the index for the number of `streams`, `chunks`, `entries`, and `bytes` that a query resolves to.
+
+URL query parameters:
+
+- `query`: The [LogQL](../logql/) matchers to check (i.e. `{job="foo", env!="dev"}`)
+- `start=<nanosecond Unix epoch>`: Start timestamp.
+- `end=<nanosecond Unix epoch>`: End timestamp.
+
+You can URL-encode these parameters directly in the request body by using the POST method and `Content-Type: application/x-www-form-urlencoded` header. This is useful when specifying a large or dynamic number of stream selectors that may breach server-side URL character limits.
+
+Response:
+```json
+{
+  "streams": 100,
+  "chunks": 1000,
+  "entries": 5000,
+  "bytes": 100000,
+}
+```
+
+It is an approximation with the following caveats:
+  * It does not include data from the ingesters
+  * It is a probabilistic technique
+  * streams/chunks which span multiple period configurations may be counted twice.
+
+These make it generally more helpful for larger queries.
+It can be used for better understanding the throughput requirements and data topology for a list of matchers over a period of time.
+
+
 ## Statistics
 
 Query endpoints such as `/api/prom/query`, `/loki/api/v1/query` and `/loki/api/v1/query_range` return a set of statistics about the query execution. Those statistics allow users to understand the amount of data processed and at which speed.

pkg/loki/modules.go

@@ -282,6 +282,7 @@ func (t *Loki) initQuerier() (services.Service, error) {
 		"/loki/api/v1/labels":              http.HandlerFunc(t.querierAPI.LabelHandler),
 		"/loki/api/v1/label/{name}/values": http.HandlerFunc(t.querierAPI.LabelHandler),
 		"/loki/api/v1/series":              http.HandlerFunc(t.querierAPI.SeriesHandler),
+		"/loki/api/v1/index/stats":         http.HandlerFunc(t.querierAPI.IndexStatsHandler),
 
 		"/api/prom/query":               httpMiddleware.Wrap(http.HandlerFunc(t.querierAPI.LogQueryHandler)),
 		"/api/prom/label":               http.HandlerFunc(t.querierAPI.LabelHandler),
@@ -675,6 +676,7 @@ func (t *Loki) initQueryFrontend() (_ services.Service, err error) {
 	t.Server.HTTP.Path("/loki/api/v1/labels").Methods("GET", "POST").Handler(frontendHandler)
 	t.Server.HTTP.Path("/loki/api/v1/label/{name}/values").Methods("GET", "POST").Handler(frontendHandler)
 	t.Server.HTTP.Path("/loki/api/v1/series").Methods("GET", "POST").Handler(frontendHandler)
+	t.Server.HTTP.Path("/loki/api/v1/index/stats").Methods("GET", "POST").Handler(frontendHandler)
 	t.Server.HTTP.Path("/api/prom/query").Methods("GET", "POST").Handler(frontendHandler)
 	t.Server.HTTP.Path("/api/prom/label").Methods("GET", "POST").Handler(frontendHandler)
 	t.Server.HTTP.Path("/api/prom/label/{name}/values").Methods("GET", "POST").Handler(frontendHandler)

pkg/querier/http.go

@@ -22,6 +22,7 @@ import (
 	"github.com/grafana/loki/pkg/logql/syntax"
 	"github.com/grafana/loki/pkg/logqlmodel"
 	"github.com/grafana/loki/pkg/logqlmodel/stats"
+	index_stats "github.com/grafana/loki/pkg/storage/stores/index/stats"
 	"github.com/grafana/loki/pkg/util/httpreq"
 	util_log "github.com/grafana/loki/pkg/util/log"
 	"github.com/grafana/loki/pkg/util/marshal"
@@ -419,6 +420,37 @@ func (q *QuerierAPI) SeriesHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// IndexStatsHandler queries the index for the data statistics related to a query
+func (q *QuerierAPI) IndexStatsHandler(w http.ResponseWriter, r *http.Request) {
+	// TODO(owen-d): use a specific type/validation instead
+	// of using range query parameters (superset)
+	req, err := loghttp.ParseRangeQuery(r)
+	if err != nil {
+		serverutil.WriteError(httpgrpc.Errorf(http.StatusBadRequest, err.Error()), w)
+		return
+	}
+
+	_, ctx := spanlogger.New(r.Context(), "query.IndexStats")
+
+	// TODO(owen-d): log metadata, record stats?
+	resp, err := q.querier.IndexStats(ctx, req)
+	if resp == nil {
+		// Some stores don't implement this
+		resp = &index_stats.Stats{}
+	}
+
+	if err != nil {
+		serverutil.WriteError(err, w)
+		return
+	}
+
+	err = marshal.WriteIndexStatsResponseJSON(resp, w)
+	if err != nil {
+		serverutil.WriteError(err, w)
+		return
+	}
+}
+
 // parseRegexQuery parses regex and query querystring from httpRequest and returns the combined LogQL query.
 // This is used only to keep regexp query string support until it gets fully deprecated.
 func parseRegexQuery(httpRequest *http.Request) (string, error) {

pkg/querier/multi_tenant_querier.go

@@ -10,9 +10,11 @@ import (
 	"github.com/grafana/dskit/tenant"
 
 	"github.com/grafana/loki/pkg/iter"
+	"github.com/grafana/loki/pkg/loghttp"
 	"github.com/grafana/loki/pkg/logproto"
 	"github.com/grafana/loki/pkg/logql"
 	"github.com/grafana/loki/pkg/logql/syntax"
+	"github.com/grafana/loki/pkg/storage/stores/index/stats"
 )
 
 const (
@@ -158,6 +160,32 @@ func (q *MultiTenantQuerier) Series(ctx context.Context, req *logproto.SeriesReq
 	return logproto.MergeSeriesResponses(responses)
 }
 
+func (q *MultiTenantQuerier) IndexStats(ctx context.Context, req *loghttp.RangeQuery) (*stats.Stats, error) {
+	tenantIDs, err := tenant.TenantIDs(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(tenantIDs) == 1 {
+		return q.Querier.IndexStats(ctx, req)
+	}
+
+	responses := make([]*stats.Stats, len(tenantIDs))
+	for i, id := range tenantIDs {
+		singleContext := user.InjectOrgID(ctx, id)
+		resp, err := q.Querier.IndexStats(singleContext, req)
+		if err != nil {
+			return nil, err
+		}
+
+		responses[i] = resp
+	}
+
+	merged := stats.MergeStats(responses...)
+
+	return &merged, nil
+}
+
 // removeTenantSelector filters the given tenant IDs based on any tenant ID filter the in passed selector.
 func removeTenantSelector(params logql.SelectSampleParams, tenantIDs []string) (map[string]struct{}, syntax.Expr, error) {
 	expr, err := params.Expr()

pkg/querier/querier.go

@@ -8,8 +8,6 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus"
 
-	"github.com/grafana/loki/pkg/storage/stores/shipper/compactor/deletion"
-
 	"github.com/go-kit/log/level"
 	"github.com/pkg/errors"
 	"github.com/prometheus/common/model"
@@ -22,7 +20,10 @@ import (
 	"github.com/grafana/loki/pkg/loghttp"
 	"github.com/grafana/loki/pkg/logproto"
 	"github.com/grafana/loki/pkg/logql"
+	"github.com/grafana/loki/pkg/logql/syntax"
 	"github.com/grafana/loki/pkg/storage"
+	"github.com/grafana/loki/pkg/storage/stores/index/stats"
+	"github.com/grafana/loki/pkg/storage/stores/shipper/compactor/deletion"
 	listutil "github.com/grafana/loki/pkg/util"
 	"github.com/grafana/loki/pkg/util/spanlogger"
 	util_validation "github.com/grafana/loki/pkg/util/validation"
@@ -83,6 +84,7 @@ type Querier interface {
 	Label(ctx context.Context, req *logproto.LabelRequest) (*logproto.LabelResponse, error)
 	Series(ctx context.Context, req *logproto.SeriesRequest) (*logproto.SeriesResponse, error)
 	Tail(ctx context.Context, req *logproto.TailRequest) (*Tailer, error)
+	IndexStats(ctx context.Context, req *loghttp.RangeQuery) (*stats.Stats, error)
 }
 
 // SingleTenantQuerier handles single tenant queries.
@@ -677,3 +679,33 @@ func (q *SingleTenantQuerier) checkTailRequestLimit(ctx context.Context) error {
 
 	return nil
 }
+
+func (q *SingleTenantQuerier) IndexStats(ctx context.Context, req *loghttp.RangeQuery) (*stats.Stats, error) {
+	userID, err := tenant.TenantID(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	start, end, err := validateQueryTimeRangeLimits(ctx, userID, q.limits, req.Start, req.End)
+	if err != nil {
+		return nil, err
+	}
+
+	matchers, err := syntax.ParseMatchers(req.Query)
+	if err != nil {
+		return nil, err
+	}
+
+	// Enforce the query timeout while querying backends
+	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(q.cfg.QueryTimeout))
+	defer cancel()
+
+	return q.store.Stats(
+		ctx,
+		userID,
+		model.TimeFromUnixNano(start.UnixNano()),
+		model.TimeFromUnixNano(end.UnixNano()),
+		matchers...,
+	)
+
+}

pkg/querier/querier_mock_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/grafana/loki/pkg/distributor/clientpool"
 	"github.com/grafana/loki/pkg/ingester/client"
 	"github.com/grafana/loki/pkg/iter"
+	"github.com/grafana/loki/pkg/loghttp"
 	"github.com/grafana/loki/pkg/logproto"
 	"github.com/grafana/loki/pkg/logql"
 	"github.com/grafana/loki/pkg/storage/chunk"
@@ -486,3 +487,7 @@ func (q *querierMock) Series(ctx context.Context, req *logproto.SeriesRequest) (
 func (q *querierMock) Tail(ctx context.Context, req *logproto.TailRequest) (*Tailer, error) {
 	return nil, errors.New("querierMock.Tail() has not been mocked")
 }
+
+func (q *querierMock) IndexStats(ctx context.Context, req *loghttp.RangeQuery) (*stats.Stats, error) {
+	return nil, nil
+}

pkg/storage/stores/shipper/indexgateway/indexgatewaypb/gateway.pb.go

@@ -660,10 +660,10 @@ func (m *IndexStatsRequest) GetMatchers() string {
 }
 
 type IndexStatsResponse struct {
-	Streams uint64 `protobuf:"varint,1,opt,name=streams,proto3" json:"streams,omitempty"`
-	Chunks  uint64 `protobuf:"varint,2,opt,name=chunks,proto3" json:"chunks,omitempty"`
-	Bytes   uint64 `protobuf:"varint,3,opt,name=bytes,proto3" json:"bytes,omitempty"`
-	Entries uint64 `protobuf:"varint,4,opt,name=entries,proto3" json:"entries,omitempty"`
+	Streams uint64 `protobuf:"varint,1,opt,name=streams,proto3" json:"streams"`
+	Chunks  uint64 `protobuf:"varint,2,opt,name=chunks,proto3" json:"chunks"`
+	Bytes   uint64 `protobuf:"varint,3,opt,name=bytes,proto3" json:"bytes"`
+	Entries uint64 `protobuf:"varint,4,opt,name=entries,proto3" json:"entries"`
 }
 
 func (m *IndexStatsResponse) Reset()      { *m = IndexStatsResponse{} }
@@ -748,63 +748,65 @@ func init() {
 }
 
 var fileDescriptor_33a7bd4603d312b2 = []byte{
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+	// 920 bytes of a gzipped FileDescriptorProto
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+	0x14, 0xf7, 0xd8, 0x5b, 0x27, 0x7e, 0x31, 0xd0, 0x4e, 0x51, 0xb1, 0x0c, 0x5d, 0xa7, 0x8b, 0x20,
+	0x11, 0x12, 0x5e, 0x28, 0xb9, 0x20, 0xc4, 0x01, 0x17, 0x88, 0x22, 0x4a, 0x55, 0x26, 0x50, 0xc1,
+	0x09, 0x8d, 0x9d, 0xf1, 0xee, 0x92, 0x5d, 0xcf, 0x76, 0x76, 0x96, 0x34, 0x37, 0xbe, 0x00, 0x12,
+	0xdf, 0x02, 0x3e, 0x05, 0x20, 0x4e, 0x3d, 0x86, 0x5b, 0xc5, 0xc1, 0x22, 0xce, 0x05, 0xe5, 0xd4,
+	0x8f, 0x80, 0xf6, 0xed, 0x5f, 0xdb, 0x49, 0x90, 0x4a, 0x2e, 0x3d, 0xed, 0xbc, 0xdf, 0x7b, 0x6f,
+	0xe6, 0xf7, 0x9b, 0x79, 0xf3, 0x66, 0xe1, 0xe3, 0x70, 0xdf, 0xb1, 0x23, 0x2d, 0x15, 0x77, 0x04,
+	0x7e, 0x45, 0x64, 0x47, 0xae, 0x17, 0x86, 0x42, 0xd9, 0xde, 0x64, 0x4f, 0x3c, 0x72, 0xb8, 0x16,
+	0x07, 0xfc, 0x70, 0xce, 0x08, 0x87, 0x76, 0x36, 0xea, 0x87, 0x4a, 0x6a, 0x49, 0x5f, 0x9c, 0xf7,
+	0x76, 0xdf, 0x76, 0x3c, 0xed, 0xc6, 0xc3, 0xfe, 0x48, 0x06, 0xb6, 0x23, 0x1d, 0x69, 0x63, 0xd8,
+	0x30, 0x1e, 0xa3, 0x85, 0x06, 0x8e, 0xd2, 0xf4, 0xee, 0xab, 0x09, 0x09, 0x5f, 0x3a, 0xa9, 0x23,
+	0x1f, 0xa4, 0x4e, 0xeb, 0xc7, 0x3a, 0xf4, 0xee, 0xf2, 0xa1, 0xf0, 0x1f, 0x70, 0x3f, 0x16, 0xd1,
+	0xa7, 0x52, 0x7d, 0x2e, 0xb4, 0xf2, 0x46, 0xf7, 0x78, 0x20, 0x98, 0x78, 0x18, 0x8b, 0x48, 0xd3,
+	0x1e, 0xac, 0x05, 0x08, 0x7e, 0x3b, 0xe1, 0x81, 0xe8, 0x90, 0x75, 0xb2, 0xd9, 0x62, 0x10, 0x14,
+	0x71, 0xf4, 0x26, 0x80, 0x9f, 0xcc, 0x91, 0xfa, 0xeb, 0xe8, 0x6f, 0x21, 0x82, 0xee, 0x3b, 0x60,
+	0x8c, 0x95, 0x0c, 0x3a, 0x8d, 0x75, 0xb2, 0xd9, 0x18, 0xd8, 0x8f, 0xa7, 0xbd, 0xda, 0x5f, 0xd3,
+	0xde, 0x46, 0x45, 0x45, 0xa8, 0x64, 0x20, 0xb4, 0x2b, 0xe2, 0xc8, 0x1e, 0xc9, 0x20, 0x90, 0x13,
+	0x3b, 0x90, 0x7b, 0xc2, 0xef, 0x7f, 0xe9, 0x05, 0x82, 0x61, 0x32, 0xdd, 0x81, 0x15, 0xed, 0x2a,
+	0x19, 0x3b, 0x6e, 0xc7, 0x78, 0xb6, 0x79, 0xf2, 0x7c, 0xda, 0x85, 0xd5, 0x80, 0xeb, 0x91, 0x2b,
+	0x54, 0xd4, 0xb9, 0x82, 0x64, 0x0b, 0xdb, 0xfa, 0x93, 0x80, 0x79, 0x37, 0x67, 0xfe, 0x8c, 0xdb,
+	0x91, 0xeb, 0xad, 0x5f, 0x92, 0xde, 0xc6, 0xff, 0xd3, 0x6b, 0x6d, 0xc0, 0x0b, 0x28, 0x89, 0x89,
+	0x28, 0x94, 0x93, 0x48, 0xd0, 0x1b, 0xd0, 0xfc, 0x1e, 0x8f, 0xbb, 0x43, 0xd6, 0x1b, 0x9b, 0x2d,
+	0x96, 0x59, 0xd6, 0xef, 0x04, 0xe8, 0xb6, 0xd0, 0x77, 0xdc, 0x78, 0xb2, 0xcf, 0xc4, 0x38, 0x17,
+	0x9c, 0xeb, 0x21, 0x97, 0xa4, 0xa7, 0x7e, 0x89, 0xe7, 0xd7, 0x58, 0x38, 0xbf, 0x0f, 0xe1, 0xfa,
+	0x9c, 0x82, 0x4c, 0xf1, 0x9b, 0x60, 0x28, 0x31, 0x4e, 0xf5, 0xae, 0xdd, 0xa6, 0xfd, 0xe2, 0x16,
+	0x14, 0x91, 0xe8, 0xb7, 0x7e, 0x25, 0x70, 0x75, 0x5b, 0xe8, 0x5d, 0xa1, 0x3c, 0x11, 0x3d, 0x8f,
+	0xfa, 0x77, 0xe0, 0x5a, 0x85, 0x7f, 0xa6, 0x7e, 0x0b, 0x9a, 0x11, 0x22, 0x99, 0xfe, 0x1b, 0xfd,
+	0xf9, 0x8e, 0xd2, 0x4f, 0xe3, 0x07, 0x46, 0x42, 0x89, 0x65, 0xb1, 0x56, 0x08, 0xcd, 0x14, 0xa7,
+	0x63, 0x68, 0xe2, 0x6d, 0xce, 0xf3, 0xaf, 0x97, 0xfb, 0x87, 0x85, 0x75, 0x9f, 0x7b, 0x6a, 0xf0,
+	0x7e, 0xa6, 0xe7, 0xdd, 0x6a, 0x77, 0x52, 0x7c, 0xcc, 0x27, 0xdc, 0xf6, 0xe5, 0xbe, 0x67, 0x57,
+	0xdb, 0x50, 0x9a, 0xf7, 0xd1, 0x1e, 0x0f, 0xb5, 0x50, 0x2c, 0x9b, 0xdd, 0xfa, 0x06, 0xe8, 0x17,
+	0xb1, 0x50, 0x87, 0x3b, 0x09, 0xbb, 0x82, 0x7d, 0x17, 0x56, 0x11, 0xfd, 0x4c, 0x1c, 0x66, 0x97,
+	0xad, 0xb0, 0xe9, 0x06, 0x18, 0x4a, 0x1e, 0x44, 0x9d, 0x7a, 0xc6, 0x6b, 0x41, 0x17, 0x93, 0x07,
+	0x0c, 0x03, 0xac, 0x0f, 0xa0, 0xc1, 0xe4, 0x01, 0x35, 0x01, 0x14, 0x9f, 0x38, 0x02, 0xbb, 0x1d,
+	0xce, 0xd6, 0x66, 0x15, 0x84, 0xbe, 0x0c, 0x57, 0xf0, 0x2e, 0xe0, 0x19, 0xb5, 0x59, 0x6a, 0x24,
+	0x9b, 0x5a, 0xe5, 0x95, 0x56, 0xc5, 0x16, 0xac, 0x24, 0x60, 0xb9, 0xab, 0xdd, 0xc5, 0xd5, 0x31,
+	0x1c, 0x13, 0x59, 0x1e, 0x9a, 0x14, 0x18, 0x94, 0x38, 0x7d, 0x0d, 0x5a, 0x9a, 0x0f, 0x7d, 0x71,
+	0xaf, 0xec, 0x24, 0x25, 0x90, 0x78, 0x5d, 0x1e, 0xb9, 0x0f, 0x0a, 0x46, 0x2d, 0x56, 0x02, 0xf4,
+	0x2d, 0xb8, 0x5a, 0x32, 0xbf, 0xaf, 0xc4, 0xd8, 0x7b, 0x84, 0xe5, 0xd0, 0x66, 0x4b, 0x38, 0xdd,
+	0x84, 0x97, 0x4a, 0x6c, 0x57, 0x73, 0xa5, 0xb1, 0x8b, 0xb6, 0xd9, 0x22, 0x9c, 0xec, 0x10, 0x8a,
+	0xfe, 0xe4, 0x61, 0xcc, 0x7d, 0x6c, 0x8f, 0x6d, 0x56, 0x41, 0xac, 0xdf, 0x08, 0x5c, 0x43, 0x01,
+	0xbb, 0x9a, 0xeb, 0xe7, 0xf2, 0x8a, 0xfc, 0x4c, 0x80, 0x56, 0x15, 0x64, 0x65, 0xf6, 0x06, 0xac,
+	0x44, 0x5a, 0x09, 0x1e, 0x44, 0xa8, 0xc2, 0x18, 0xac, 0x9d, 0x4e, 0x7b, 0x39, 0xc4, 0xf2, 0x01,
+	0xb5, 0xa0, 0x39, 0x4a, 0x7a, 0x46, 0x84, 0x1c, 0x8d, 0x01, 0x9c, 0x4e, 0x7b, 0x19, 0xc2, 0xb2,
+	0x2f, 0xed, 0xc1, 0x95, 0xe1, 0xa1, 0x16, 0xe9, 0xd2, 0xc6, 0xa0, 0x75, 0x3a, 0xed, 0xa5, 0x00,
+	0x4b, 0x3f, 0xc9, 0x5a, 0x62, 0xa2, 0xb1, 0x76, 0x8c, 0x72, 0xad, 0x0c, 0x62, 0xf9, 0xe0, 0xf6,
+	0x1f, 0x06, 0xb4, 0x91, 0xe9, 0x76, 0x5a, 0x53, 0xf4, 0x2b, 0x80, 0xb2, 0x10, 0xe9, 0xad, 0xc5,
+	0x82, 0x5b, 0x2a, 0xd2, 0xae, 0x75, 0x51, 0x48, 0x2a, 0xfc, 0x1d, 0x42, 0xbf, 0x86, 0xb5, 0x4a,
+	0xd3, 0xa4, 0x4b, 0x49, 0xcb, 0x6f, 0x42, 0xf7, 0xf5, 0x0b, 0x63, 0xd2, 0x99, 0xad, 0x1a, 0x65,
+	0xd0, 0x2a, 0xda, 0x11, 0x5d, 0x3f, 0x23, 0x67, 0xae, 0xd3, 0x76, 0x6f, 0x5d, 0x10, 0x51, 0xcc,
+	0xf9, 0x1d, 0xbc, 0x72, 0xce, 0x0b, 0x4d, 0xfb, 0x8b, 0xf9, 0x17, 0x3f, 0xe5, 0xdd, 0x9b, 0x67,
+	0xc6, 0x57, 0xd6, 0xf2, 0xa1, 0x73, 0xde, 0xdf, 0x11, 0xb5, 0xcf, 0x4c, 0x3e, 0xff, 0x3f, 0xea,
+	0xbf, 0x57, 0xdb, 0x85, 0xd5, 0x44, 0x70, 0x52, 0x96, 0xcb, 0x87, 0xbb, 0x74, 0xe9, 0x96, 0x0f,
+	0x77, 0xb9, 0xaa, 0xad, 0xda, 0x60, 0xeb, 0xe8, 0xd8, 0xac, 0x3d, 0x39, 0x36, 0x6b, 0x4f, 0x8f,
+	0x4d, 0xf2, 0xc3, 0xcc, 0x24, 0xbf, 0xcc, 0x4c, 0xf2, 0x78, 0x66, 0x92, 0xa3, 0x99, 0x49, 0xfe,
+	0x9e, 0x99, 0xe4, 0x9f, 0x99, 0x59, 0x7b, 0x3a, 0x33, 0xc9, 0x4f, 0x27, 0x66, 0xed, 0xe8, 0xc4,
+	0xac, 0x3d, 0x39, 0x31, 0x6b, 0xc3, 0x26, 0xb6, 0xe9, 0xf7, 0xfe, 0x0d, 0x00, 0x00, 0xff, 0xff,
+	0x79, 0x39, 0x20, 0x44, 0xc2, 0x0a, 0x00, 0x00,
 }
 
 func (this *LabelValuesForMetricNameRequest) Equal(that interface{}) bool {

pkg/storage/stores/shipper/indexgateway/indexgatewaypb/gateway.proto

@@ -125,8 +125,8 @@ message IndexStatsRequest {
 }
 
 message IndexStatsResponse {
-  uint64 streams = 1;
-  uint64 chunks = 2;
-  uint64 bytes = 3;
-  uint64 entries = 4;
+  uint64 streams = 1 [(gogoproto.jsontag) = "streams"];
+  uint64 chunks = 2 [(gogoproto.jsontag) = "chunks"];
+  uint64 bytes = 3 [(gogoproto.jsontag) = "bytes"];
+  uint64 entries = 4 [(gogoproto.jsontag) = "entries"];
 }

pkg/storage/stores/tsdb/multitenant.go

@@ -29,8 +29,8 @@ func NewMultiTenantIndex(idx Index) *MultiTenantIndex {
 
 func withTenantLabelMatcher(userID string, matchers []*labels.Matcher) []*labels.Matcher {
 	cpy := make([]*labels.Matcher, len(matchers)+1)
-	copy(cpy, matchers)
-	cpy = append(cpy, labels.MustNewMatcher(labels.MatchEqual, TenantLabel, userID))
+	cpy[0] = labels.MustNewMatcher(labels.MatchEqual, TenantLabel, userID)
+	copy(cpy[1:], matchers)
 	return cpy
 }
 

pkg/util/marshal/marshal.go

@@ -5,14 +5,14 @@ package marshal
 import (
 	"io"
 
-	"github.com/grafana/loki/pkg/logqlmodel"
-
 	"github.com/gorilla/websocket"
 	jsoniter "github.com/json-iterator/go"
 
 	"github.com/grafana/loki/pkg/loghttp"
 	legacy "github.com/grafana/loki/pkg/loghttp/legacy"
 	"github.com/grafana/loki/pkg/logproto"
+	"github.com/grafana/loki/pkg/logqlmodel"
+	"github.com/grafana/loki/pkg/storage/stores/index/stats"
 )
 
 // WriteQueryResponseJSON marshals the promql.Value to v1 loghttp JSON and then
@@ -86,3 +86,9 @@ type seriesResponseAdapter struct {
 	Status string              `json:"status"`
 	Data   []map[string]string `json:"data"`
 }
+
+// WriteIndexStatsResponseJSON marshals a gatewaypb.Stats to JSON and then
+// writes it to the provided io.Writer.
+func WriteIndexStatsResponseJSON(r *stats.Stats, w io.Writer) error {
+	return jsoniter.NewEncoder(w).Encode(r)
+}