[release-2.8.x] Expose optional label matcher for label values handler (#8824)

CHANGELOG.md

@@ -6,6 +6,12 @@
 
 ##### Enhancements
 
+* [8824](https://github.com/grafana/loki/pull/8824) **periklis**: Expose optional label matcher for label values handler
+* [8852](https://github.com/grafana/loki/pull/8852) **wtchangdm**: Loki: Add `route_randomly` to Redis options.
+* [8848](https://github.com/grafana/loki/pull/8848) **dannykopping**: Ruler: add configurable rule evaluation jitter.
+* [8752](https://github.com/grafana/loki/pull/8752) **chaudum**: Add query fairness control across actors within a tenant to scheduler, which can be enabled by passing the `X-Loki-Actor-Path` header to the HTTP request of the query.
+* [8786](https://github.com/grafana/loki/pull/8786) **DylanGuedes**: Ingester: add new /ingester/prepare_shutdown endpoint.
+* [8744](https://github.com/grafana/loki/pull/8744) **dannykopping**: Ruler: remote rule evaluation.
 * [8727](https://github.com/grafana/loki/pull/8727) **cstyan** **jeschkies**: Propagate per-request limit header to querier.
 * [8682](https://github.com/grafana/loki/pull/8682) **dannykopping**: Add fetched chunk size distribution metric `loki_chunk_fetcher_fetched_size_bytes`.
 * [8532](https://github.com/grafana/loki/pull/8532) **justcompile**: Adds Storage Class option to S3 objects

docs/sources/api/_index.md

@@ -483,6 +483,7 @@ It accepts the following query parameters in the URL:
 - `start`: The start time for the query as a nanosecond Unix epoch. Defaults to 6 hours ago.
 - `end`: The end time for the query as a nanosecond Unix epoch. Defaults to now.
 - `since`: A `duration` used to calculate `start` relative to `end`. If `end` is in the future, `start` is calculated as this duration before now. Any value specified for `start` supersedes this parameter.
+- `query`: A set of log stream selector that selects the streams to match and return label values for `<name>`. Example: `{"app": "myapp", "environment": "dev"}`
 
 In microservices mode, `/loki/api/v1/label/<name>/values` is exposed by the querier.
 

pkg/ingester/ingester.go

@@ -828,7 +828,16 @@ func (i *Ingester) Label(ctx context.Context, req *logproto.LabelRequest) (*logp
 	if err != nil {
 		return nil, err
 	}
-	resp, err := instance.Label(ctx, req)
+
+	var matchers []*labels.Matcher
+	if req.Query != "" {
+		matchers, err = syntax.ParseMatchers(req.Query)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	resp, err := instance.Label(ctx, req, matchers...)
 	if err != nil {
 		return nil, err
 	}

pkg/loghttp/labels.go

@@ -82,5 +82,7 @@ func ParseLabelQuery(r *http.Request) (*logproto.LabelRequest, error) {
 	}
 	req.Start = &start
 	req.End = &end
+
+	req.Query = query(r)
 	return req, nil
 }

pkg/logproto/logproto.proto

@@ -119,6 +119,7 @@ message LabelRequest {
     (gogoproto.stdtime) = true,
     (gogoproto.nullable) = true
   ];
+  string query = 5; // Naming this query instead of match because this should be with queryrangebase.Request interface
 }
 
 message LabelResponse {

pkg/logql/metrics.go

@@ -177,7 +177,7 @@ func RecordLabelQueryMetrics(
 	ctx context.Context,
 	log log.Logger,
 	start, end time.Time,
-	label, status string,
+	label, query, status string,
 	stats logql_stats.Result,
 ) {
 	var (
@@ -199,6 +199,7 @@ func RecordLabelQueryMetrics(
 		"duration", time.Duration(int64(stats.Summary.ExecTime*float64(time.Second))),
 		"status", status,
 		"label", label,
+		"query", query,
 		"splits", stats.Summary.Splits,
 		"throughput", strings.Replace(humanize.Bytes(uint64(stats.Summary.BytesProcessedPerSecond)), " ", "", 1),
 		"total_bytes", strings.Replace(humanize.Bytes(uint64(stats.Summary.TotalBytesProcessed)), " ", "", 1),

pkg/logql/metrics_test.go

@@ -101,7 +101,7 @@ func TestLogLabelsQuery(t *testing.T) {
 	sp := opentracing.StartSpan("")
 	ctx := opentracing.ContextWithSpan(user.InjectOrgID(context.Background(), "foo"), sp)
 	now := time.Now()
-	RecordLabelQueryMetrics(ctx, logger, now.Add(-1*time.Hour), now, "foo", "200", stats.Result{
+	RecordLabelQueryMetrics(ctx, logger, now.Add(-1*time.Hour), now, "foo", "", "200", stats.Result{
 		Summary: stats.Summary{
 			BytesProcessedPerSecond: 100000,
 			ExecTime:                25.25,
@@ -111,7 +111,7 @@ func TestLogLabelsQuery(t *testing.T) {
 	})
 	require.Equal(t,
 		fmt.Sprintf(
-			"level=info org_id=foo traceID=%s latency=slow query_type=labels length=1h0m0s duration=25.25s status=200 label=foo splits=0 throughput=100kB total_bytes=100kB total_entries=12\n",
+			"level=info org_id=foo traceID=%s latency=slow query_type=labels length=1h0m0s duration=25.25s status=200 label=foo query= splits=0 throughput=100kB total_bytes=100kB total_entries=12\n",
 			sp.Context().(jaeger.SpanContext).SpanID().String(),
 		),
 		buf.String())

pkg/querier/http.go

@@ -222,7 +222,7 @@ func (q *QuerierAPI) LabelHandler(w http.ResponseWriter, r *http.Request) {
 		status, _ = server.ClientHTTPStatusAndError(err)
 	}
 
-	logql.RecordLabelQueryMetrics(ctx, log, *req.Start, *req.End, req.Name, strconv.Itoa(status), statResult)
+	logql.RecordLabelQueryMetrics(ctx, log, *req.Start, *req.End, req.Name, req.Query, strconv.Itoa(status), statResult)
 
 	if err != nil {
 		serverutil.WriteError(err, w)

pkg/querier/querier.go

@@ -11,6 +11,7 @@ import (
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
+	"github.com/prometheus/prometheus/model/labels"
 	"github.com/weaveworks/common/httpgrpc"
 	"golang.org/x/sync/errgroup"
 	"google.golang.org/grpc/health/grpc_health_v1"
@@ -364,6 +365,14 @@ func (q *SingleTenantQuerier) Label(ctx context.Context, req *logproto.LabelRequ
 		return nil, err
 	}
 
+	var matchers []*labels.Matcher
+	if req.Query != "" {
+		matchers, err = syntax.ParseMatchers(req.Query)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	// Enforce the query timeout while querying backends
 	queryTimeout := q.limits.QueryTimeout(ctx, userID)
 	// TODO: remove this clause once we remove the deprecated query-timeout flag.
@@ -401,7 +410,7 @@ func (q *SingleTenantQuerier) Label(ctx context.Context, req *logproto.LabelRequ
 			)
 
 			if req.Values {
-				storeValues, err = q.store.LabelValuesForMetricName(ctx, userID, from, through, "logs", req.Name)
+				storeValues, err = q.store.LabelValuesForMetricName(ctx, userID, from, through, "logs", req.Name, matchers...)
 			} else {
 				storeValues, err = q.store.LabelNamesForMetricName(ctx, userID, from, through, "logs")
 			}

pkg/querier/queryrange/codec.go

@@ -186,10 +186,6 @@ func (r *LokiLabelNamesRequest) WithQuery(query string) queryrangebase.Request {
 	return &new
 }
 
-func (r *LokiLabelNamesRequest) GetQuery() string {
-	return ""
-}
-
 func (r *LokiLabelNamesRequest) GetStep() int64 {
 	return 0
 }
@@ -259,6 +255,7 @@ func (Codec) DecodeRequest(_ context.Context, r *http.Request, forwardHeaders []
 			StartTs: *req.Start,
 			EndTs:   *req.End,
 			Path:    r.URL.Path,
+			Query:   req.Query,
 		}, nil
 	case IndexStatsOp:
 		req, err := loghttp.ParseIndexStatsQuery(r)
@@ -340,6 +337,7 @@ func (Codec) EncodeRequest(ctx context.Context, r queryrangebase.Request) (*http
 		params := url.Values{
 			"start": []string{fmt.Sprintf("%d", request.StartTs.UnixNano())},
 			"end":   []string{fmt.Sprintf("%d", request.EndTs.UnixNano())},
+			"query": []string{request.GetQuery()},
 		}
 
 		u := &url.URL{

pkg/querier/queryrange/codec_test.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	strings "strings"
 	"testing"
 	"time"
@@ -80,6 +81,15 @@ func Test_codec_DecodeRequest(t *testing.T) {
 			StartTs: start,
 			EndTs:   end,
 		}, false},
+		{"label_values", func() (*http.Request, error) {
+			return http.NewRequest(http.MethodGet,
+				fmt.Sprintf(`/label/test/values?start=%d&end=%d&query={foo="bar"}`, start.UnixNano(), end.UnixNano()), nil)
+		}, &LokiLabelNamesRequest{
+			Path:    "/label/test/values",
+			StartTs: start,
+			EndTs:   end,
+			Query:   `{foo="bar"}`,
+		}, false},
 		{"index_stats", func() (*http.Request, error) {
 			return LokiCodec.EncodeRequest(context.Background(), &logproto.IndexStatsRequest{
 				From:     model.TimeFromUnixNano(start.UnixNano()),
@@ -334,20 +344,45 @@ func Test_codec_labels_EncodeRequest(t *testing.T) {
 		Path:    "/loki/api/v1/labels/__name__/values",
 		StartTs: start,
 		EndTs:   end,
+		Query:   `{foo="bar"}`,
 	}
 	got, err = LokiCodec.EncodeRequest(ctx, toEncode)
 	require.NoError(t, err)
 	require.Equal(t, ctx, got.Context())
 	require.Equal(t, "/loki/api/v1/labels/__name__/values", got.URL.Path)
 	require.Equal(t, fmt.Sprintf("%d", start.UnixNano()), got.URL.Query().Get("start"))
 	require.Equal(t, fmt.Sprintf("%d", end.UnixNano()), got.URL.Query().Get("end"))
+	require.Equal(t, `{foo="bar"}`, got.URL.Query().Get("query"))
 
 	// testing a full roundtrip
 	req, err = LokiCodec.DecodeRequest(context.TODO(), got, nil)
 	require.NoError(t, err)
 	require.Equal(t, toEncode.StartTs, req.(*LokiLabelNamesRequest).StartTs)
 	require.Equal(t, toEncode.EndTs, req.(*LokiLabelNamesRequest).EndTs)
+	require.Equal(t, toEncode.Query, req.(*LokiLabelNamesRequest).Query)
+	require.Equal(t, "/loki/api/v1/labels/__name__/values", req.(*LokiLabelNamesRequest).Path)
+}
+
+func Test_codec_labels_DecodeRequest(t *testing.T) {
+	ctx := context.Background()
+	u, err := url.Parse(`/loki/api/v1/labels/__name__/values?start=1575285010000000010&end=1575288610000000010&query={foo="bar"}`)
+	require.NoError(t, err)
+
+	r := &http.Request{URL: u}
+	req, err := LokiCodec.DecodeRequest(context.TODO(), r, nil)
+	require.NoError(t, err)
+	require.Equal(t, start, req.(*LokiLabelNamesRequest).StartTs)
+	require.Equal(t, end, req.(*LokiLabelNamesRequest).EndTs)
+	require.Equal(t, `{foo="bar"}`, req.(*LokiLabelNamesRequest).Query)
 	require.Equal(t, "/loki/api/v1/labels/__name__/values", req.(*LokiLabelNamesRequest).Path)
+
+	got, err := LokiCodec.EncodeRequest(ctx, req)
+	require.NoError(t, err)
+	require.Equal(t, ctx, got.Context())
+	require.Equal(t, "/loki/api/v1/labels/__name__/values", got.URL.Path)
+	require.Equal(t, fmt.Sprintf("%d", start.UnixNano()), got.URL.Query().Get("start"))
+	require.Equal(t, fmt.Sprintf("%d", end.UnixNano()), got.URL.Query().Get("end"))
+	require.Equal(t, `{foo="bar"}`, got.URL.Query().Get("query"))
 }
 
 func Test_codec_index_stats_EncodeRequest(t *testing.T) {