receiver: Expose stats for all tenants

Thanos Receiver supports the Prometheus tsdb status API and can expose
TSDB stats for a single tenant.

This commit extends that functionality and allows users to request
TSDB stats for all tenants using the all_tenants=true query parameter.

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

CHANGELOG.md

@@ -15,6 +15,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 ### Added
 
 - [#5440](https://github.com/thanos-io/thanos/pull/5440) HTTP metrics: export number of in-flight HTTP requests.
+- [#5402](https://github.com/thanos-io/thanos/pull/5402) Receive: Implement exposing TSDB stats for all tenants 
 
 ### Changed
 

cmd/thanos/receive.go

@@ -213,7 +213,7 @@ func runReceive(
 		TLSConfig:         rwTLSConfig,
 		DialOpts:          dialOpts,
 		ForwardTimeout:    time.Duration(*conf.forwardTimeout),
-		GetTSDBStats:      dbs.Stats,
+		TSDBStats:         dbs,
 	})
 
 	grpcProbe := prober.NewGRPC()

pkg/api/status/v1.go

@@ -18,15 +18,14 @@ package status
 
 import (
 	"fmt"
-	"math"
 	"net/http"
 
+	"github.com/prometheus/prometheus/tsdb"
+
 	"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"
@@ -49,32 +48,35 @@ func convertStats(stats []index.Stat) []Stat {
 	return result
 }
 
+type TenantStats struct {
+	Tenant string
+	Stats  *tsdb.Stats
+}
+
 // TSDBStatus has information of cardinality statistics from postings.
+// TODO(fpetkovski): replace with upstream struct after dependency update.
 type TSDBStatus struct {
+	Tenant                      string       `json:"tenant"`
 	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 GetStatsFunc func(r *http.Request, statsByLabelName string) ([]TenantStats, *api.ApiError)
 
 type Options struct {
 	GetStats GetStatsFunc
-	Registry *prometheus.Registry
 }
 
-// TODO(fpetkovski): replace with upstream struct after dependency update.
 type StatusAPI struct {
 	getTSDBStats GetStatsFunc
-	options      Options
 }
 
 func New(opts Options) *StatusAPI {
 	return &StatusAPI{
 		getTSDBStats: opts.GetStats,
-		options:      opts,
 	}
 }
 
@@ -84,43 +86,30 @@ func (sapi *StatusAPI) Register(r *route.Router, tracer opentracing.Tracer, logg
 }
 
 func (sapi *StatusAPI) httpServeStats(r *http.Request) (interface{}, []error, *api.ApiError) {
-	s, err := sapi.getTSDBStats(r, labels.MetricName)
+	stats, err := sapi.getTSDBStats(r, labels.MetricName)
 	if err != nil {
-		return nil, nil, &api.ApiError{Typ: api.ErrorInternal, Err: err}
+		return nil, nil, err
 	}
 
-	if s == nil {
+	if stats == 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
-			}
-		}
+	result := make([]TSDBStatus, 0, len(stats))
+	for _, s := range stats {
+		result = append(result, TSDBStatus{
+			Tenant: s.Tenant,
+			HeadStats: v1.HeadStats{
+				NumSeries:     s.Stats.NumSeries,
+				MinTime:       s.Stats.MinTime,
+				MaxTime:       s.Stats.MaxTime,
+				NumLabelPairs: s.Stats.IndexPostingStats.NumLabelPairs,
+			},
+			SeriesCountByMetricName:     convertStats(s.Stats.IndexPostingStats.CardinalityMetricsStats),
+			LabelValueCountByLabelName:  convertStats(s.Stats.IndexPostingStats.CardinalityLabelStats),
+			MemoryInBytesByLabelName:    convertStats(s.Stats.IndexPostingStats.LabelValueStats),
+			SeriesCountByLabelValuePair: convertStats(s.Stats.IndexPostingStats.LabelValuePairsStats),
+		})
 	}
-
-	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
-
+	return result, nil, nil
 }

pkg/receive/handler.go

@@ -17,6 +17,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/thanos-io/thanos/pkg/api"
+
 	statusapi "github.com/thanos-io/thanos/pkg/api/status"
 	"github.com/thanos-io/thanos/pkg/logging"
 
@@ -57,6 +59,8 @@ const (
 	DefaultTenantLabel = "tenant_id"
 	// DefaultReplicaHeader is the default header used to designate the replica count of a write request.
 	DefaultReplicaHeader = "THANOS-REPLICA"
+	// AllTenantsQueryParam is the query parameter for getting TSDB stats for all tenants.
+	AllTenantsQueryParam = "all_tenants"
 	// Labels for metrics.
 	labelSuccess = "success"
 	labelError   = "error"
@@ -95,7 +99,7 @@ type Options struct {
 	DialOpts          []grpc.DialOption
 	ForwardTimeout    time.Duration
 	RelabelConfigs    []*relabel.Config
-	GetTSDBStats      GetStatsFunc
+	TSDBStats         TSDBStats
 }
 
 // Handler serves a Prometheus remote write receiving HTTP endpoint.
@@ -226,7 +230,6 @@ func NewHandler(logger log.Logger, o *Options) *Handler {
 
 	statusAPI := statusapi.New(statusapi.Options{
 		GetStats: h.getStats,
-		Registry: o.Registry,
 	})
 	statusAPI.Register(h.router, o.Tracer, logger, ins, logging.NewHTTPServerMiddleware(logger))
 
@@ -271,17 +274,32 @@ func (h *Handler) testReady(f http.HandlerFunc) http.HandlerFunc {
 	}
 }
 
-func (h *Handler) getStats(r *http.Request, statsByLabelName string) (*tsdb.Stats, error) {
+func (h *Handler) getStats(r *http.Request, statsByLabelName string) ([]statusapi.TenantStats, *api.ApiError) {
 	if !h.isReady() {
-		return nil, fmt.Errorf("service unavailable")
+		return nil, &api.ApiError{Typ: api.ErrorInternal, Err: fmt.Errorf("service unavailable")}
 	}
 
 	tenantID := r.Header.Get(h.options.TenantHeader)
+	getAllTenantStats := r.FormValue(AllTenantsQueryParam) == "true"
+	if getAllTenantStats && tenantID != "" {
+		err := fmt.Errorf("using both the %s parameter and the %s header is not supported", AllTenantsQueryParam, h.options.TenantHeader)
+		return nil, &api.ApiError{Typ: api.ErrorBadData, Err: err}
+	}
+
+	if getAllTenantStats {
+		return h.options.TSDBStats.AllTenantStats(statsByLabelName), nil
+	}
+
 	if tenantID == "" {
 		tenantID = h.options.DefaultTenantID
 	}
 
-	return h.options.GetTSDBStats(tenantID, statsByLabelName), nil
+	stats := h.options.TSDBStats.SingleTenantStats(tenantID, statsByLabelName)
+	if stats == nil {
+		return nil, nil
+	}
+
+	return []statusapi.TenantStats{*stats}, nil
 }
 
 // Close stops the Handler.

pkg/receive/multitsdb.go

@@ -12,6 +12,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/thanos-io/thanos/pkg/api/status"
+
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 	"github.com/pkg/errors"
@@ -32,7 +34,10 @@ import (
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 )
 
-type GetStatsFunc func(tenantID, statsByLabelName string) *tsdb.Stats
+type TSDBStats interface {
+	SingleTenantStats(tenantID, statsByLabelName string) *status.TenantStats
+	AllTenantStats(statsByLabelName string) []status.TenantStats
+}
 
 type MultiTSDB struct {
 	dataDir         string
@@ -375,7 +380,7 @@ func (t *MultiTSDB) TSDBExemplars() map[string]*exemplars.TSDB {
 	return res
 }
 
-func (t *MultiTSDB) Stats(tenantID, statsByLabelName string) *tsdb.Stats {
+func (t *MultiTSDB) SingleTenantStats(tenantID, statsByLabelName string) *status.TenantStats {
 	t.mtx.RLock()
 	defer t.mtx.RUnlock()
 
@@ -384,7 +389,39 @@ func (t *MultiTSDB) Stats(tenantID, statsByLabelName string) *tsdb.Stats {
 		return nil
 	}
 
-	return tenant.readyS.get().db.Head().Stats(statsByLabelName)
+	stats := tenant.readyS.get().db.Head().Stats(statsByLabelName)
+	return &status.TenantStats{
+		Tenant: tenantID,
+		Stats:  stats,
+	}
+}
+
+func (t *MultiTSDB) AllTenantStats(statsByLabelName string) []status.TenantStats {
+	t.mtx.RLock()
+	defer t.mtx.RUnlock()
+
+	var (
+		mu     sync.Mutex
+		wg     sync.WaitGroup
+		result = make([]status.TenantStats, 0, len(t.tenants))
+	)
+	for tenantID, tenantInstance := range t.tenants {
+		wg.Add(1)
+		go func(tenantID string, tenantInstance *tenant) {
+			defer wg.Done()
+			stats := tenantInstance.readyS.get().db.Head().Stats(statsByLabelName)
+
+			mu.Lock()
+			defer mu.Unlock()
+			result = append(result, status.TenantStats{
+				Tenant: tenantID,
+				Stats:  stats,
+			})
+		}(tenantID, tenantInstance)
+	}
+	wg.Wait()
+
+	return result
 }
 
 func (t *MultiTSDB) startTSDB(logger log.Logger, tenantID string, tenant *tenant) error {