Query Label Names and Values from blocks store

CHANGELOG.md

@@ -13,7 +13,7 @@
 * [ENHANCEMENT] Added `cortex_alertmanager_config_hash` metric to expose hash of Alertmanager Config loaded per user. #3388
 * [ENHANCEMENT] Query-Frontend / Query-Scheduler: New component called "Query-Scheduler" has been introduced. Query-Scheduler is simply a queue of requests, moved outside of Query-Frontend. This allows Query-Frontend to be scaled separately from number of queues. To make Query-Frontend and Querier use Query-Scheduler, they need to be started with `-frontend.scheduler-address` and `-querier.scheduler-address` options respectively. #3374 #3471
 * [ENHANCEMENT] Query-frontend / Querier / Ruler: added `-querier.max-query-lookback` to limit how long back data (series and metadata) can be queried. This setting can be overridden on a per-tenant basis and is enforced in the query-frontend, querier and ruler. #3452 #3458
-* [ENHANCEMENT] Querier: added `-querier.query-store-for-labels-enabled` to query store for series API. Only works with blocks storage engine. #3461
+* [ENHANCEMENT] Querier: added `-querier.query-store-for-labels-enabled` to query store for label names, label values and series APIs. Only works with blocks storage engine. #3461 #3520
 * [ENHANCEMENT] Ingester: exposed `-blocks-storage.tsdb.wal-segment-size-bytes` config option to customise the TSDB WAL segment max size. #3476
 * [ENHANCEMENT] Compactor: concurrently run blocks cleaner for multiple tenants. Concurrency can be configured via `-compactor.cleanup-concurrency`. #3483
 * [ENHANCEMENT] Compactor: shuffle tenants before running compaction. #3483

Makefile

@@ -87,6 +87,7 @@ pkg/ruler/rules/rules.pb.go: pkg/ruler/rules/rules.proto
 pkg/ruler/ruler.pb.go: pkg/ruler/rules/rules.proto
 pkg/ring/kv/memberlist/kv.pb.go: pkg/ring/kv/memberlist/kv.proto
 pkg/scheduler/schedulerpb/scheduler.pb.go: pkg/scheduler/schedulerpb/scheduler.proto
+pkg/storegateway/storegatewaypb/gateway.pb.go: pkg/storegateway/storegatewaypb/gateway.proto
 pkg/chunk/grpc/grpc.pb.go: pkg/chunk/grpc/grpc.proto
 tools/blocksconvert/scheduler.pb.go: tools/blocksconvert/scheduler.proto
 

docs/api/_index.md

@@ -294,7 +294,7 @@ GET,POST <prometheus-http-prefix>/api/v1/labels
 GET,POST <legacy-http-prefix>/api/v1/labels
 ```
 
-Get label names of ingested series. Differently than Prometheus and due to scalability and performances reasons, Cortex currently ignores the `start` and `end` request parameters and always fetches the label names from in-memory data stored in the ingesters.
+Get label names of ingested series. Differently than Prometheus and due to scalability and performances reasons, Cortex currently ignores the `start` and `end` request parameters and always fetches the label names from in-memory data stored in the ingesters. There is experimental support to query the long-term store with the *blocks* storage engine when `-querier.query-store-for-labels-enabled` is set.
 
 _For more information, please check out the Prometheus [get label names](https://prometheus.io/docs/prometheus/latest/querying/api/#getting-label-names) documentation._
 
@@ -309,7 +309,7 @@ GET <prometheus-http-prefix>/api/v1/label/{name}/values
 GET <legacy-http-prefix>/api/v1/label/{name}/values
 ```
 
-Get label values for a given label name. Differently than Prometheus and due to scalability and performances reasons, Cortex currently ignores the `start` and `end` request parameters and always fetches the label values from in-memory data stored in the ingesters.
+Get label values for a given label name. Differently than Prometheus and due to scalability and performances reasons, Cortex currently ignores the `start` and `end` request parameters and always fetches the label values from in-memory data stored in the ingesters. There is experimental support to query the long-term store with the *blocks* storage engine when `-querier.query-store-for-labels-enabled` is set.
 
 _For more information, please check out the Prometheus [get label values](https://prometheus.io/docs/prometheus/latest/querying/api/#querying-label-values) documentation._
 

integration/querier_test.go

@@ -536,10 +536,10 @@ func testMetadataQueriesWithBlocksStorage(
 			labelValuesTests: []labelValuesTest{
 				{
 					label: labels.MetricName,
-					resp:  []string{lastSeriesInIngesterBlocksName, firstSeriesInIngesterHeadName},
+					resp:  []string{lastSeriesInStorageName, lastSeriesInIngesterBlocksName, firstSeriesInIngesterHeadName},
 				},
 			},
-			labelNames: []string{labels.MetricName, lastSeriesInIngesterBlocksName, firstSeriesInIngesterHeadName},
+			labelNames: []string{labels.MetricName, lastSeriesInStorageName, lastSeriesInIngesterBlocksName, firstSeriesInIngesterHeadName},
 		},
 		"query metadata entirely outside the ingester range should return the head data as well": {
 			from: lastSeriesInStorageTs.Add(-2 * blockRangePeriod),
@@ -563,10 +563,10 @@ func testMetadataQueriesWithBlocksStorage(
 			labelValuesTests: []labelValuesTest{
 				{
 					label: labels.MetricName,
-					resp:  []string{firstSeriesInIngesterHeadName},
+					resp:  []string{lastSeriesInStorageName, firstSeriesInIngesterHeadName},
 				},
 			},
-			labelNames: []string{labels.MetricName, firstSeriesInIngesterHeadName},
+			labelNames: []string{labels.MetricName, lastSeriesInStorageName, firstSeriesInIngesterHeadName},
 		},
 	}
 
@@ -590,7 +590,7 @@ func testMetadataQueriesWithBlocksStorage(
 				for _, val := range lvt.resp {
 					exp = append(exp, model.LabelValue(val))
 				}
-				require.ElementsMatch(t, exp, labelsRes)
+				require.Equal(t, exp, labelsRes)
 			}
 
 			labelNames, err := c.LabelNames(tc.from, tc.to)

pkg/distributor/distributor.go

@@ -672,6 +672,10 @@ func (d *Distributor) LabelValuesForLabelName(ctx context.Context, from, to mode
 	for v := range valueSet {
 		values = append(values, v)
 	}
+
+	// We need the values returned to be sorted.
+	sort.Strings(values)
+
 	return values, nil
 }
 
@@ -704,9 +708,8 @@ func (d *Distributor) LabelNames(ctx context.Context, from, to model.Time) ([]st
 	for v := range valueSet {
 		values = append(values, v)
 	}
-	sort.Slice(values, func(i, j int) bool {
-		return values[i] < values[j]
-	})
+
+	sort.Strings(values)
 
 	return values, nil
 }