Expose tsdb status in receiver

This commit implements the api/v1/status/tsdb API in the Receiver.

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>

CHANGELOG.md

@@ -18,6 +18,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 
 - [#5352](https://github.com/thanos-io/thanos/pull/5352) Cache: Add cache metrics to groupcache.
 - [#5391](https://github.com/thanos-io/thanos/pull/5391) Receive: Add relabeling support.
+- [#5391](https://github.com/thanos-io/thanos/pull/5391) Receive: Implement api/v1/status/tsdb.
 
 ### Changed
 

cmd/thanos/receive.go

@@ -211,6 +211,7 @@ func runReceive(
 		TLSConfig:         rwTLSConfig,
 		DialOpts:          dialOpts,
 		ForwardTimeout:    time.Duration(*conf.forwardTimeout),
+		GetTSDBStats:      dbs.Stats,
 	})
 
 	grpcProbe := prober.NewGRPC()

pkg/api/status/v1.go

@@ -0,0 +1,125 @@
+// Copyright (c) The Thanos Authors.
+// Licensed under the Apache License 2.0.
+
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package status
+
+import (
+	"fmt"
+	"math"
+	"net/http"
+
+	"github.com/go-kit/log"
+	"github.com/opentracing/opentracing-go"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/route"
+	"github.com/prometheus/prometheus/model/labels"
+	"github.com/prometheus/prometheus/tsdb"
+	"github.com/prometheus/prometheus/tsdb/index"
+	v1 "github.com/prometheus/prometheus/web/api/v1"
+	"github.com/thanos-io/thanos/pkg/api"
+	extpromhttp "github.com/thanos-io/thanos/pkg/extprom/http"
+	"github.com/thanos-io/thanos/pkg/logging"
+)
+
+// Stat holds the information about individual cardinality.
+type Stat struct {
+	Name  string `json:"name"`
+	Value uint64 `json:"value"`
+}
+
+func convertStats(stats []index.Stat) []Stat {
+	result := make([]Stat, 0, len(stats))
+	for _, item := range stats {
+		item := Stat{Name: item.Name, Value: item.Count}
+		result = append(result, item)
+	}
+	return result
+}
+
+// TSDBStatus has information of cardinality statistics from postings.
+type TSDBStatus struct {
+	HeadStats                   v1.HeadStats `json:"headStats"`
+	SeriesCountByMetricName     []Stat       `json:"seriesCountByMetricName"`
+	LabelValueCountByLabelName  []Stat       `json:"labelValueCountByLabelName"`
+	MemoryInBytesByLabelName    []Stat       `json:"memoryInBytesByLabelName"`
+	SeriesCountByLabelValuePair []Stat       `json:"seriesCountByLabelValuePair"`
+}
+
+type GetStatsFunc func(r *http.Request, statsByLabelName string) (*tsdb.Stats, error)
+
+type Options struct {
+	GetStats GetStatsFunc
+	Registry *prometheus.Registry
+}
+
+type StatusAPI struct {
+	getTSDBStats GetStatsFunc
+	options      Options
+}
+
+func New(opts Options) *StatusAPI {
+	return &StatusAPI{
+		getTSDBStats: opts.GetStats,
+		options:      opts,
+	}
+}
+
+func (sapi *StatusAPI) Register(r *route.Router, tracer opentracing.Tracer, logger log.Logger, ins extpromhttp.InstrumentationMiddleware, logMiddleware *logging.HTTPServerMiddleware) {
+	instr := api.GetInstr(tracer, logger, ins, logMiddleware, false)
+	r.Get("/api/v1/status/tsdb", instr("tsdb_status", sapi.httpServeStats))
+}
+
+func (sapi *StatusAPI) httpServeStats(r *http.Request) (interface{}, []error, *api.ApiError) {
+	s, err := sapi.getTSDBStats(r, labels.MetricName)
+	if err != nil {
+		return nil, nil, &api.ApiError{Typ: api.ErrorInternal, Err: err}
+	}
+
+	if s == nil {
+		return nil, nil, &api.ApiError{Typ: api.ErrorBadData, Err: fmt.Errorf("unknown tenant")}
+	}
+
+	metrics, err := sapi.options.Registry.Gather()
+	if err != nil {
+		return nil, []error{err}, nil
+	}
+
+	chunkCount := int64(math.NaN())
+	for _, mF := range metrics {
+		if *mF.Name == "prometheus_tsdb_head_chunks" {
+			m := *mF.Metric[0]
+			if m.Gauge != nil {
+				chunkCount = int64(m.Gauge.GetValue())
+				break
+			}
+		}
+	}
+
+	return TSDBStatus{
+		HeadStats: v1.HeadStats{
+			NumSeries:     s.NumSeries,
+			ChunkCount:    chunkCount,
+			MinTime:       s.MinTime,
+			MaxTime:       s.MaxTime,
+			NumLabelPairs: s.IndexPostingStats.NumLabelPairs,
+		},
+		SeriesCountByMetricName:     convertStats(s.IndexPostingStats.CardinalityMetricsStats),
+		LabelValueCountByLabelName:  convertStats(s.IndexPostingStats.CardinalityLabelStats),
+		MemoryInBytesByLabelName:    convertStats(s.IndexPostingStats.LabelValueStats),
+		SeriesCountByLabelValuePair: convertStats(s.IndexPostingStats.LabelValuePairsStats),
+	}, nil, nil
+
+}

pkg/receive/handler.go

@@ -17,6 +17,9 @@ import (
 	"sync"
 	"time"
 
+	statusapi "github.com/thanos-io/thanos/pkg/api/status"
+	"github.com/thanos-io/thanos/pkg/logging"
+
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 	"github.com/gogo/protobuf/proto"
@@ -72,7 +75,7 @@ var (
 type Options struct {
 	Writer            *Writer
 	ListenAddress     string
-	Registry          prometheus.Registerer
+	Registry          *prometheus.Registry
 	TenantHeader      string
 	DefaultTenantID   string
 	ReplicaHeader     string
@@ -84,6 +87,7 @@ type Options struct {
 	DialOpts          []grpc.DialOption
 	ForwardTimeout    time.Duration
 	RelabelConfigs    []*relabel.Config
+	GetTSDBStats      GetStatsFunc
 }
 
 // Handler serves a Prometheus remote write receiving HTTP endpoint.
@@ -173,6 +177,12 @@ func NewHandler(logger log.Logger, o *Options) *Handler {
 
 	h.router.Post("/api/v1/receive", instrf("receive", readyf(middleware.RequestID(http.HandlerFunc(h.receiveHTTP)))))
 
+	statusAPI := statusapi.New(statusapi.Options{
+		GetStats: h.getStats,
+		Registry: o.Registry,
+	})
+	statusAPI.Register(h.router, o.Tracer, logger, ins, logging.NewHTTPServerMiddleware(logger))
+
 	return h
 }
 
@@ -214,6 +224,19 @@ func (h *Handler) testReady(f http.HandlerFunc) http.HandlerFunc {
 	}
 }
 
+func (h *Handler) getStats(r *http.Request, statsByLabelName string) (*tsdb.Stats, error) {
+	if !h.isReady() {
+		return nil, fmt.Errorf("service unavailable")
+	}
+
+	tenantID := r.Header.Get(h.options.TenantHeader)
+	if tenantID == "" {
+		tenantID = h.options.DefaultTenantID
+	}
+
+	return h.options.GetTSDBStats(tenantID, statsByLabelName), nil
+}
+
 // Close stops the Handler.
 func (h *Handler) Close() {
 	if h.listener != nil {

pkg/receive/multitsdb.go

@@ -31,6 +31,8 @@ import (
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 )
 
+type GetStatsFunc func(tenantID, statsByLabelName string) *tsdb.Stats
+
 type MultiTSDB struct {
 	dataDir         string
 	logger          log.Logger
@@ -289,6 +291,18 @@ func (t *MultiTSDB) TSDBExemplars() map[string]*exemplars.TSDB {
 	return res
 }
 
+func (t *MultiTSDB) Stats(tenantID, statsByLabelName string) *tsdb.Stats {
+	t.mtx.RLock()
+	defer t.mtx.RUnlock()
+
+	tenant, ok := t.tenants[tenantID]
+	if !ok {
+		return nil
+	}
+
+	return tenant.readyS.get().db.Head().Stats(statsByLabelName)
+}
+
 func (t *MultiTSDB) startTSDB(logger log.Logger, tenantID string, tenant *tenant) error {
 	reg := prometheus.WrapRegistererWith(prometheus.Labels{"tenant": tenantID}, t.reg)
 	lset := labelpb.ExtendSortedLabels(t.labels, labels.FromStrings(t.tenantLabelName, tenantID))