Add streaming remote read to ReadClient (#11379)

* Add streaming remote read to ReadClient

Signed-off-by: Justin Lei <justin.lei@grafana.com>

* Apply suggestions from code review

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Signed-off-by: Justin Lei <justin.lei@grafana.com>

* Remote read instrumentation tweaks

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* Minor cleanups

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* In-line handleChunkedResponse

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* Fix lints

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* Explicitly call cancel() when needed

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* Update chunkedSeries, chunkedSeriesIterator for new interfaces

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* Adapt remote.chunkedSeries to use prompb.ChunkedSeries

Signed-off-by: Justin Lei <lei.justin@gmail.com>

* Fix lint

Signed-off-by: Justin Lei <lei.justin@gmail.com>

---------

Signed-off-by: Justin Lei <justin.lei@grafana.com>
Signed-off-by: Justin Lei <lei.justin@gmail.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>

config/config.go

@@ -221,6 +221,7 @@ var (
 	// DefaultRemoteReadConfig is the default remote read configuration.
 	DefaultRemoteReadConfig = RemoteReadConfig{
 		RemoteTimeout:        model.Duration(1 * time.Minute),
+		ChunkedReadLimit:     DefaultChunkedReadLimit,
 		HTTPClientConfig:     config.DefaultHTTPClientConfig,
 		FilterExternalLabels: true,
 	}
@@ -1279,13 +1280,20 @@ type MetadataConfig struct {
 	MaxSamplesPerSend int `yaml:"max_samples_per_send,omitempty"`
 }
 
+const (
+	// DefaultChunkedReadLimit is the default value for the maximum size of the protobuf frame client allows.
+	// 50MB is the default. This is equivalent to ~100k full XOR chunks and average labelset.
+	DefaultChunkedReadLimit = 5e+7
+)
+
 // RemoteReadConfig is the configuration for reading from remote storage.
 type RemoteReadConfig struct {
-	URL           *config.URL       `yaml:"url"`
-	RemoteTimeout model.Duration    `yaml:"remote_timeout,omitempty"`
-	Headers       map[string]string `yaml:"headers,omitempty"`
-	ReadRecent    bool              `yaml:"read_recent,omitempty"`
-	Name          string            `yaml:"name,omitempty"`
+	URL              *config.URL       `yaml:"url"`
+	RemoteTimeout    model.Duration    `yaml:"remote_timeout,omitempty"`
+	ChunkedReadLimit uint64            `yaml:"chunked_read_limit,omitempty"`
+	Headers          map[string]string `yaml:"headers,omitempty"`
+	ReadRecent       bool              `yaml:"read_recent,omitempty"`
+	Name             string            `yaml:"name,omitempty"`
 
 	// We cannot do proper Go type embedding below as the parser will then parse
 	// values arbitrarily into the overflow maps of further-down types.

config/config_test.go

@@ -165,10 +165,11 @@ var expectedConf = &Config{
 
 	RemoteReadConfigs: []*RemoteReadConfig{
 		{
-			URL:           mustParseURL("http://remote1/read"),
-			RemoteTimeout: model.Duration(1 * time.Minute),
-			ReadRecent:    true,
-			Name:          "default",
+			URL:              mustParseURL("http://remote1/read"),
+			RemoteTimeout:    model.Duration(1 * time.Minute),
+			ChunkedReadLimit: DefaultChunkedReadLimit,
+			ReadRecent:       true,
+			Name:             "default",
 			HTTPClientConfig: config.HTTPClientConfig{
 				FollowRedirects: true,
 				EnableHTTP2:     false,
@@ -178,6 +179,7 @@ var expectedConf = &Config{
 		{
 			URL:              mustParseURL("http://remote3/read"),
 			RemoteTimeout:    model.Duration(1 * time.Minute),
+			ChunkedReadLimit: DefaultChunkedReadLimit,
 			ReadRecent:       false,
 			Name:             "read_special",
 			RequiredMatchers: model.LabelSet{"job": "special"},

storage/remote/chunked.go

@@ -26,10 +26,6 @@ import (
 	"github.com/gogo/protobuf/proto"
 )
 
-// DefaultChunkedReadLimit is the default value for the maximum size of the protobuf frame client allows.
-// 50MB is the default. This is equivalent to ~100k full XOR chunks and average labelset.
-const DefaultChunkedReadLimit = 5e+7
-
 // The table gets initialized with sync.Once but may still cause a race
 // with any other use of the crc32 package anywhere. Thus we initialize it
 // before.

storage/remote/client.go

@@ -16,6 +16,7 @@ package remote
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -36,13 +37,14 @@ import (
 
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/prompb"
+	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/storage/remote/azuread"
 	"github.com/prometheus/prometheus/storage/remote/googleiam"
 )
 
-const maxErrMsgLen = 1024
-
 const (
+	maxErrMsgLen = 1024
+
 	RemoteWriteVersionHeader        = "X-Prometheus-Remote-Write-Version"
 	RemoteWriteVersion1HeaderValue  = "0.1.0"
 	RemoteWriteVersion20HeaderValue = "2.0.0"
@@ -68,9 +70,12 @@ var (
 		config.RemoteWriteProtoMsgV1: appProtoContentType, // Also application/x-protobuf;proto=prometheus.WriteRequest but simplified for compatibility with 1.x spec.
 		config.RemoteWriteProtoMsgV2: appProtoContentType + ";proto=io.prometheus.write.v2.Request",
 	}
-)
 
-var (
+	AcceptedResponseTypes = []prompb.ReadRequest_ResponseType{
+		prompb.ReadRequest_STREAMED_XOR_CHUNKS,
+		prompb.ReadRequest_SAMPLES,
+	}
+
 	remoteReadQueriesTotal = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: namespace,
@@ -78,7 +83,7 @@ var (
 			Name:      "read_queries_total",
 			Help:      "The total number of remote read queries.",
 		},
-		[]string{remoteName, endpoint, "code"},
+		[]string{remoteName, endpoint, "response_type", "code"},
 	)
 	remoteReadQueries = prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{
@@ -94,13 +99,13 @@ var (
 			Namespace:                       namespace,
 			Subsystem:                       subsystem,
 			Name:                            "read_request_duration_seconds",
-			Help:                            "Histogram of the latency for remote read requests.",
+			Help:                            "Histogram of the latency for remote read requests. Note that for streamed responses this is only the duration of the initial call and does not include the processing of the stream.",
 			Buckets:                         append(prometheus.DefBuckets, 25, 60),
 			NativeHistogramBucketFactor:     1.1,
 			NativeHistogramMaxBucketNumber:  100,
 			NativeHistogramMinResetDuration: 1 * time.Hour,
 		},
-		[]string{remoteName, endpoint},
+		[]string{remoteName, endpoint, "response_type"},
 	)
 )
 
@@ -116,10 +121,11 @@ type Client struct {
 	timeout    time.Duration
 
 	retryOnRateLimit bool
+	chunkedReadLimit uint64
 
 	readQueries         prometheus.Gauge
 	readQueriesTotal    *prometheus.CounterVec
-	readQueriesDuration prometheus.Observer
+	readQueriesDuration prometheus.ObserverVec
 
 	writeProtoMsg    config.RemoteWriteProtoMsg
 	writeCompression Compression // Not exposed by ClientConfig for now.
@@ -136,12 +142,13 @@ type ClientConfig struct {
 	Headers          map[string]string
 	RetryOnRateLimit bool
 	WriteProtoMsg    config.RemoteWriteProtoMsg
+	ChunkedReadLimit uint64
 }
 
-// ReadClient uses the SAMPLES method of remote read to read series samples from remote server.
-// TODO(bwplotka): Add streamed chunked remote read method as well (https://github.com/prometheus/prometheus/issues/5926).
+// ReadClient will request the STREAMED_XOR_CHUNKS method of remote read but can
+// also fall back to the SAMPLES method if necessary.
 type ReadClient interface {
-	Read(ctx context.Context, query *prompb.Query) (*prompb.QueryResult, error)
+	Read(ctx context.Context, query *prompb.Query, sortSeries bool) (storage.SeriesSet, error)
 }
 
 // NewReadClient creates a new client for remote read.
@@ -162,9 +169,10 @@ func NewReadClient(name string, conf *ClientConfig) (ReadClient, error) {
 		urlString:           conf.URL.String(),
 		Client:              httpClient,
 		timeout:             time.Duration(conf.Timeout),
+		chunkedReadLimit:    conf.ChunkedReadLimit,
 		readQueries:         remoteReadQueries.WithLabelValues(name, conf.URL.String()),
 		readQueriesTotal:    remoteReadQueriesTotal.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
-		readQueriesDuration: remoteReadQueryDuration.WithLabelValues(name, conf.URL.String()),
+		readQueriesDuration: remoteReadQueryDuration.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
 	}, nil
 }
 
@@ -278,8 +286,8 @@ func (c *Client) Store(ctx context.Context, req []byte, attempt int) (WriteRespo
 		return WriteResponseStats{}, RecoverableError{err, defaultBackoff}
 	}
 	defer func() {
-		io.Copy(io.Discard, httpResp.Body)
-		httpResp.Body.Close()
+		_, _ = io.Copy(io.Discard, httpResp.Body)
+		_ = httpResp.Body.Close()
 	}()
 
 	// TODO(bwplotka): Pass logger and emit debug on error?
@@ -329,17 +337,17 @@ func (c *Client) Endpoint() string {
 	return c.urlString
 }
 
-// Read reads from a remote endpoint.
-func (c *Client) Read(ctx context.Context, query *prompb.Query) (*prompb.QueryResult, error) {
+// Read reads from a remote endpoint. The sortSeries parameter is only respected in the case of a sampled response;
+// chunked responses arrive already sorted by the server.
+func (c *Client) Read(ctx context.Context, query *prompb.Query, sortSeries bool) (storage.SeriesSet, error) {
 	c.readQueries.Inc()
 	defer c.readQueries.Dec()
 
 	req := &prompb.ReadRequest{
 		// TODO: Support batching multiple queries into one read request,
 		// as the protobuf interface allows for it.
-		Queries: []*prompb.Query{
-			query,
-		},
+		Queries:               []*prompb.Query{query},
+		AcceptedResponseTypes: AcceptedResponseTypes,
 	}
 	data, err := proto.Marshal(req)
 	if err != nil {
@@ -358,7 +366,6 @@ func (c *Client) Read(ctx context.Context, query *prompb.Query) (*prompb.QueryRe
 	httpReq.Header.Set("X-Prometheus-Remote-Read-Version", "0.1.0")
 
 	ctx, cancel := context.WithTimeout(ctx, c.timeout)
-	defer cancel()
 
 	ctx, span := otel.Tracer("").Start(ctx, "Remote Read", trace.WithSpanKind(trace.SpanKindClient))
 	defer span.End()
@@ -366,24 +373,58 @@ func (c *Client) Read(ctx context.Context, query *prompb.Query) (*prompb.QueryRe
 	start := time.Now()
 	httpResp, err := c.Client.Do(httpReq.WithContext(ctx))
 	if err != nil {
+		cancel()
 		return nil, fmt.Errorf("error sending request: %w", err)
 	}
-	defer func() {
-		io.Copy(io.Discard, httpResp.Body)
-		httpResp.Body.Close()
-	}()
-	c.readQueriesDuration.Observe(time.Since(start).Seconds())
-	c.readQueriesTotal.WithLabelValues(strconv.Itoa(httpResp.StatusCode)).Inc()
-
-	compressed, err = io.ReadAll(httpResp.Body)
-	if err != nil {
-		return nil, fmt.Errorf("error reading response. HTTP status code: %s: %w", httpResp.Status, err)
-	}
 
 	if httpResp.StatusCode/100 != 2 {
-		return nil, fmt.Errorf("remote server %s returned HTTP status %s: %s", c.urlString, httpResp.Status, strings.TrimSpace(string(compressed)))
+		// Make an attempt at getting an error message.
+		body, _ := io.ReadAll(httpResp.Body)
+		_ = httpResp.Body.Close()
+
+		cancel()
+		return nil, fmt.Errorf("remote server %s returned http status %s: %s", c.urlString, httpResp.Status, string(body))
 	}
 
+	contentType := httpResp.Header.Get("Content-Type")
+
+	switch {
+	case strings.HasPrefix(contentType, "application/x-protobuf"):
+		c.readQueriesDuration.WithLabelValues("sampled").Observe(time.Since(start).Seconds())
+		c.readQueriesTotal.WithLabelValues("sampled", strconv.Itoa(httpResp.StatusCode)).Inc()
+		ss, err := c.handleSampledResponse(req, httpResp, sortSeries)
+		cancel()
+		return ss, err
+	case strings.HasPrefix(contentType, "application/x-streamed-protobuf; proto=prometheus.ChunkedReadResponse"):
+		c.readQueriesDuration.WithLabelValues("chunked").Observe(time.Since(start).Seconds())
+
+		s := NewChunkedReader(httpResp.Body, c.chunkedReadLimit, nil)
+		return NewChunkedSeriesSet(s, httpResp.Body, query.StartTimestampMs, query.EndTimestampMs, func(err error) {
+			code := strconv.Itoa(httpResp.StatusCode)
+			if !errors.Is(err, io.EOF) {
+				code = "aborted_stream"
+			}
+			c.readQueriesTotal.WithLabelValues("chunked", code).Inc()
+			cancel()
+		}), nil
+	default:
+		c.readQueriesDuration.WithLabelValues("unsupported").Observe(time.Since(start).Seconds())
+		c.readQueriesTotal.WithLabelValues("unsupported", strconv.Itoa(httpResp.StatusCode)).Inc()
+		cancel()
+		return nil, fmt.Errorf("unsupported content type: %s", contentType)
+	}
+}
+
+func (c *Client) handleSampledResponse(req *prompb.ReadRequest, httpResp *http.Response, sortSeries bool) (storage.SeriesSet, error) {
+	compressed, err := io.ReadAll(httpResp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("error reading response. HTTP status code: %s: %w", httpResp.Status, err)
+	}
+	defer func() {
+		_, _ = io.Copy(io.Discard, httpResp.Body)
+		_ = httpResp.Body.Close()
+	}()
+
 	uncompressed, err := snappy.Decode(nil, compressed)
 	if err != nil {
 		return nil, fmt.Errorf("error reading response: %w", err)
@@ -399,5 +440,8 @@ func (c *Client) Read(ctx context.Context, query *prompb.Query) (*prompb.QueryRe
 		return nil, fmt.Errorf("responses: want %d, got %d", len(req.Queries), len(resp.Results))
 	}
 
-	return resp.Results[0], nil
+	// This client does not batch queries so there's always only 1 result.
+	res := resp.Results[0]
+
+	return FromQueryResult(sortSeries, res), nil
 }

storage/remote/client_test.go

@@ -23,9 +23,15 @@ import (
 	"testing"
 	"time"
 
+	"github.com/gogo/protobuf/proto"
+	"github.com/golang/snappy"
 	config_util "github.com/prometheus/common/config"
 	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
+
+	"github.com/prometheus/prometheus/config"
+	"github.com/prometheus/prometheus/prompb"
+	"github.com/prometheus/prometheus/tsdb/chunkenc"
 )
 
 var longErrMessage = strings.Repeat("error message", maxErrMsgLen)
@@ -208,3 +214,226 @@ func TestClientCustomHeaders(t *testing.T) {
 
 	require.True(t, called, "The remote server wasn't called")
 }
+
+func TestReadClient(t *testing.T) {
+	tests := []struct {
+		name                  string
+		query                 *prompb.Query
+		httpHandler           http.HandlerFunc
+		expectedLabels        []map[string]string
+		expectedSamples       [][]model.SamplePair
+		expectedErrorContains string
+		sortSeries            bool
+	}{
+		{
+			name:        "sorted sampled response",
+			httpHandler: sampledResponseHTTPHandler(t),
+			expectedLabels: []map[string]string{
+				{"foo1": "bar"},
+				{"foo2": "bar"},
+			},
+			expectedSamples: [][]model.SamplePair{
+				{
+					{Timestamp: model.Time(0), Value: model.SampleValue(3)},
+					{Timestamp: model.Time(5), Value: model.SampleValue(4)},
+				},
+				{
+					{Timestamp: model.Time(0), Value: model.SampleValue(1)},
+					{Timestamp: model.Time(5), Value: model.SampleValue(2)},
+				},
+			},
+			expectedErrorContains: "",
+			sortSeries:            true,
+		},
+		{
+			name:        "unsorted sampled response",
+			httpHandler: sampledResponseHTTPHandler(t),
+			expectedLabels: []map[string]string{
+				{"foo2": "bar"},
+				{"foo1": "bar"},
+			},
+			expectedSamples: [][]model.SamplePair{
+				{
+					{Timestamp: model.Time(0), Value: model.SampleValue(1)},
+					{Timestamp: model.Time(5), Value: model.SampleValue(2)},
+				},
+				{
+					{Timestamp: model.Time(0), Value: model.SampleValue(3)},
+					{Timestamp: model.Time(5), Value: model.SampleValue(4)},
+				},
+			},
+			expectedErrorContains: "",
+			sortSeries:            false,
+		},
+		{
+			name: "chunked response",
+			query: &prompb.Query{
+				StartTimestampMs: 4000,
+				EndTimestampMs:   12000,
+			},
+			httpHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("Content-Type", "application/x-streamed-protobuf; proto=prometheus.ChunkedReadResponse")
+
+				flusher, ok := w.(http.Flusher)
+				require.True(t, ok)
+
+				cw := NewChunkedWriter(w, flusher)
+				l := []prompb.Label{
+					{Name: "foo", Value: "bar"},
+				}
+
+				chunks := buildTestChunks(t)
+				for i, c := range chunks {
+					cSeries := prompb.ChunkedSeries{Labels: l, Chunks: []prompb.Chunk{c}}
+					readResp := prompb.ChunkedReadResponse{
+						ChunkedSeries: []*prompb.ChunkedSeries{&cSeries},
+						QueryIndex:    int64(i),
+					}
+
+					b, err := proto.Marshal(&readResp)
+					require.NoError(t, err)
+
+					_, err = cw.Write(b)
+					require.NoError(t, err)
+				}
+			}),
+			expectedLabels: []map[string]string{
+				{"foo": "bar"},
+				{"foo": "bar"},
+				{"foo": "bar"},
+			},
+			// This is the output of buildTestChunks minus the samples outside the query range.
+			expectedSamples: [][]model.SamplePair{
+				{
+					{Timestamp: model.Time(4000), Value: model.SampleValue(4)},
+				},
+				{
+					{Timestamp: model.Time(5000), Value: model.SampleValue(1)},
+					{Timestamp: model.Time(6000), Value: model.SampleValue(2)},
+					{Timestamp: model.Time(7000), Value: model.SampleValue(3)},
+					{Timestamp: model.Time(8000), Value: model.SampleValue(4)},
+					{Timestamp: model.Time(9000), Value: model.SampleValue(5)},
+				},
+				{
+					{Timestamp: model.Time(10000), Value: model.SampleValue(2)},
+					{Timestamp: model.Time(11000), Value: model.SampleValue(3)},
+					{Timestamp: model.Time(12000), Value: model.SampleValue(4)},
+				},
+			},
+			expectedErrorContains: "",
+		},
+		{
+			name: "unsupported content type",
+			httpHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("Content-Type", "foobar")
+			}),
+			expectedErrorContains: "unsupported content type",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			server := httptest.NewServer(test.httpHandler)
+			defer server.Close()
+
+			u, err := url.Parse(server.URL)
+			require.NoError(t, err)
+
+			conf := &ClientConfig{
+				URL:              &config_util.URL{URL: u},
+				Timeout:          model.Duration(5 * time.Second),
+				ChunkedReadLimit: config.DefaultChunkedReadLimit,
+			}
+			c, err := NewReadClient("test", conf)
+			require.NoError(t, err)
+
+			query := &prompb.Query{}
+			if test.query != nil {
+				query = test.query
+			}
+
+			ss, err := c.Read(context.Background(), query, test.sortSeries)
+			if test.expectedErrorContains != "" {
+				require.ErrorContains(t, err, test.expectedErrorContains)
+				return
+			}
+
+			require.NoError(t, err)
+
+			i := 0
+
+			for ss.Next() {
+				require.NoError(t, ss.Err())
+				s := ss.At()
+
+				l := s.Labels()
+				require.Len(t, test.expectedLabels[i], l.Len())
+				for k, v := range test.expectedLabels[i] {
+					require.True(t, l.Has(k))
+					require.Equal(t, v, l.Get(k))
+				}
+
+				it := s.Iterator(nil)
+				j := 0
+
+				for valType := it.Next(); valType != chunkenc.ValNone; valType = it.Next() {
+					require.NoError(t, it.Err())
+
+					ts, v := it.At()
+					expectedSample := test.expectedSamples[i][j]
+
+					require.Equal(t, int64(expectedSample.Timestamp), ts)
+					require.Equal(t, float64(expectedSample.Value), v)
+
+					j++
+				}
+
+				require.Len(t, test.expectedSamples[i], j)
+
+				i++
+			}
+
+			require.NoError(t, ss.Err())
+		})
+	}
+}
+
+func sampledResponseHTTPHandler(t *testing.T) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/x-protobuf")
+
+		resp := prompb.ReadResponse{
+			Results: []*prompb.QueryResult{
+				{
+					Timeseries: []*prompb.TimeSeries{
+						{
+							Labels: []prompb.Label{
+								{Name: "foo2", Value: "bar"},
+							},
+							Samples: []prompb.Sample{
+								{Value: float64(1), Timestamp: int64(0)},
+								{Value: float64(2), Timestamp: int64(5)},
+							},
+							Exemplars: []prompb.Exemplar{},
+						},
+						{
+							Labels: []prompb.Label{
+								{Name: "foo1", Value: "bar"},
+							},
+							Samples: []prompb.Sample{
+								{Value: float64(3), Timestamp: int64(0)},
+								{Value: float64(4), Timestamp: int64(5)},
+							},
+							Exemplars: []prompb.Exemplar{},
+						},
+					},
+				},
+			},
+		}
+		b, err := proto.Marshal(&resp)
+		require.NoError(t, err)
+
+		_, err = w.Write(snappy.Encode(nil, b))
+		require.NoError(t, err)
+	}
+}

storage/remote/codec.go

@@ -540,6 +540,220 @@ func (c *concreteSeriesIterator) Err() error {
 	return nil
 }
 
+// chunkedSeriesSet implements storage.SeriesSet.
+type chunkedSeriesSet struct {
+	chunkedReader *ChunkedReader
+	respBody      io.ReadCloser
+	mint, maxt    int64
+	cancel        func(error)
+
+	current storage.Series
+	err     error
+}
+
+func NewChunkedSeriesSet(chunkedReader *ChunkedReader, respBody io.ReadCloser, mint, maxt int64, cancel func(error)) storage.SeriesSet {
+	return &chunkedSeriesSet{
+		chunkedReader: chunkedReader,
+		respBody:      respBody,
+		mint:          mint,
+		maxt:          maxt,
+		cancel:        cancel,
+	}
+}
+
+// Next return true if there is a next series and false otherwise. It will
+// block until the next series is available.
+func (s *chunkedSeriesSet) Next() bool {
+	res := &prompb.ChunkedReadResponse{}
+
+	err := s.chunkedReader.NextProto(res)
+	if err != nil {
+		if !errors.Is(err, io.EOF) {
+			s.err = err
+			_, _ = io.Copy(io.Discard, s.respBody)
+		}
+
+		_ = s.respBody.Close()
+		s.cancel(err)
+
+		return false
+	}
+
+	s.current = &chunkedSeries{
+		ChunkedSeries: prompb.ChunkedSeries{
+			Labels: res.ChunkedSeries[0].Labels,
+			Chunks: res.ChunkedSeries[0].Chunks,
+		},
+		mint: s.mint,
+		maxt: s.maxt,
+	}
+
+	return true
+}
+
+func (s *chunkedSeriesSet) At() storage.Series {
+	return s.current
+}
+
+func (s *chunkedSeriesSet) Err() error {
+	return s.err
+}
+
+func (s *chunkedSeriesSet) Warnings() annotations.Annotations {
+	return nil
+}
+
+type chunkedSeries struct {
+	prompb.ChunkedSeries
+	mint, maxt int64
+}
+
+var _ storage.Series = &chunkedSeries{}
+
+func (s *chunkedSeries) Labels() labels.Labels {
+	b := labels.NewScratchBuilder(0)
+	return s.ToLabels(&b, nil)
+}
+
+func (s *chunkedSeries) Iterator(it chunkenc.Iterator) chunkenc.Iterator {
+	csIt, ok := it.(*chunkedSeriesIterator)
+	if ok {
+		csIt.reset(s.Chunks, s.mint, s.maxt)
+		return csIt
+	}
+	return newChunkedSeriesIterator(s.Chunks, s.mint, s.maxt)
+}
+
+type chunkedSeriesIterator struct {
+	chunks     []prompb.Chunk
+	idx        int
+	cur        chunkenc.Iterator
+	valType    chunkenc.ValueType
+	mint, maxt int64
+
+	err error
+}
+
+var _ chunkenc.Iterator = &chunkedSeriesIterator{}
+
+func newChunkedSeriesIterator(chunks []prompb.Chunk, mint, maxt int64) *chunkedSeriesIterator {
+	it := &chunkedSeriesIterator{}
+	it.reset(chunks, mint, maxt)
+	return it
+}
+
+func (it *chunkedSeriesIterator) Next() chunkenc.ValueType {
+	if it.err != nil {
+		return chunkenc.ValNone
+	}
+	if len(it.chunks) == 0 {
+		return chunkenc.ValNone
+	}
+
+	for it.valType = it.cur.Next(); it.valType != chunkenc.ValNone; it.valType = it.cur.Next() {
+		atT := it.AtT()
+		if atT > it.maxt {
+			it.chunks = nil // Exhaust this iterator so follow-up calls to Next or Seek return fast.
+			return chunkenc.ValNone
+		}
+		if atT >= it.mint {
+			return it.valType
+		}
+	}
+
+	if it.idx >= len(it.chunks)-1 {
+		it.valType = chunkenc.ValNone
+	} else {
+		it.idx++
+		it.resetIterator()
+		it.valType = it.Next()
+	}
+
+	return it.valType
+}
+
+func (it *chunkedSeriesIterator) Seek(t int64) chunkenc.ValueType {
+	if it.err != nil {
+		return chunkenc.ValNone
+	}
+	if len(it.chunks) == 0 {
+		return chunkenc.ValNone
+	}
+
+	startIdx := it.idx
+	it.idx += sort.Search(len(it.chunks)-startIdx, func(i int) bool {
+		return it.chunks[startIdx+i].MaxTimeMs >= t
+	})
+	if it.idx > startIdx {
+		it.resetIterator()
+	} else {
+		ts := it.cur.AtT()
+		if ts >= t {
+			return it.valType
+		}
+	}
+
+	for it.valType = it.cur.Next(); it.valType != chunkenc.ValNone; it.valType = it.cur.Next() {
+		ts := it.cur.AtT()
+		if ts > it.maxt {
+			it.chunks = nil // Exhaust this iterator so follow-up calls to Next or Seek return fast.
+			return chunkenc.ValNone
+		}
+		if ts >= t && ts >= it.mint {
+			return it.valType
+		}
+	}
+
+	it.valType = chunkenc.ValNone
+	return it.valType
+}
+
+func (it *chunkedSeriesIterator) resetIterator() {
+	if it.idx < len(it.chunks) {
+		chunk := it.chunks[it.idx]
+
+		decodedChunk, err := chunkenc.FromData(chunkenc.Encoding(chunk.Type), chunk.Data)
+		if err != nil {
+			it.err = err
+			return
+		}
+
+		it.cur = decodedChunk.Iterator(nil)
+	} else {
+		it.cur = chunkenc.NewNopIterator()
+	}
+}
+
+func (it *chunkedSeriesIterator) reset(chunks []prompb.Chunk, mint, maxt int64) {
+	it.chunks = chunks
+	it.mint = mint
+	it.maxt = maxt
+	it.idx = 0
+	if len(chunks) > 0 {
+		it.resetIterator()
+	}
+}
+
+func (it *chunkedSeriesIterator) At() (ts int64, v float64) {
+	return it.cur.At()
+}
+
+func (it *chunkedSeriesIterator) AtHistogram(h *histogram.Histogram) (int64, *histogram.Histogram) {
+	return it.cur.AtHistogram(h)
+}
+
+func (it *chunkedSeriesIterator) AtFloatHistogram(fh *histogram.FloatHistogram) (int64, *histogram.FloatHistogram) {
+	return it.cur.AtFloatHistogram(fh)
+}
+
+func (it *chunkedSeriesIterator) AtT() int64 {
+	return it.cur.AtT()
+}
+
+func (it *chunkedSeriesIterator) Err() error {
+	return it.err
+}
+
 // validateLabelsAndMetricName validates the label names/values and metric names returned from remote read,
 // also making sure that there are no labels with duplicate names.
 func validateLabelsAndMetricName(ls []prompb.Label) error {
@@ -612,15 +826,6 @@ func FromLabelMatchers(matchers []*prompb.LabelMatcher) ([]*labels.Matcher, erro
 	return result, nil
 }
 
-// LabelProtosToMetric unpack a []*prompb.Label to a model.Metric.
-func LabelProtosToMetric(labelPairs []*prompb.Label) model.Metric {
-	metric := make(model.Metric, len(labelPairs))
-	for _, l := range labelPairs {
-		metric[model.LabelName(l.Name)] = model.LabelValue(l.Value)
-	}
-	return metric
-}
-
 // DecodeWriteRequest from an io.Reader into a prompb.WriteRequest, handling
 // snappy decompression.
 // Used also by documentation/examples/remote_storage.

storage/remote/codec_test.go

@@ -16,6 +16,7 @@ package remote
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"sync"
 	"testing"
 
@@ -24,6 +25,7 @@ import (
 	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
 
+	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/model/metadata"
@@ -705,3 +707,270 @@ func (c *mockChunkIterator) Next() bool {
 func (c *mockChunkIterator) Err() error {
 	return nil
 }
+
+func TestChunkedSeriesIterator(t *testing.T) {
+	t.Run("happy path", func(t *testing.T) {
+		chks := buildTestChunks(t)
+
+		it := newChunkedSeriesIterator(chks, 2000, 12000)
+
+		require.NoError(t, it.err)
+		require.NotNil(t, it.cur)
+
+		// Initial next; advance to first valid sample of first chunk.
+		res := it.Next()
+		require.Equal(t, chunkenc.ValFloat, res)
+		require.NoError(t, it.Err())
+
+		ts, v := it.At()
+		require.Equal(t, int64(2000), ts)
+		require.Equal(t, float64(2), v)
+
+		// Next to the second sample of the first chunk.
+		res = it.Next()
+		require.Equal(t, chunkenc.ValFloat, res)
+		require.NoError(t, it.Err())
+
+		ts, v = it.At()
+		require.Equal(t, int64(3000), ts)
+		require.Equal(t, float64(3), v)
+
+		// Attempt to seek to the first sample of the first chunk (should return current sample).
+		res = it.Seek(0)
+		require.Equal(t, chunkenc.ValFloat, res)
+
+		ts, v = it.At()
+		require.Equal(t, int64(3000), ts)
+		require.Equal(t, float64(3), v)
+
+		// Seek to the end of the first chunk.
+		res = it.Seek(4000)
+		require.Equal(t, chunkenc.ValFloat, res)
+
+		ts, v = it.At()
+		require.Equal(t, int64(4000), ts)
+		require.Equal(t, float64(4), v)
+
+		// Next to the first sample of the second chunk.
+		res = it.Next()
+		require.Equal(t, chunkenc.ValFloat, res)
+		require.NoError(t, it.Err())
+
+		ts, v = it.At()
+		require.Equal(t, int64(5000), ts)
+		require.Equal(t, float64(1), v)
+
+		// Seek to the second sample of the third chunk.
+		res = it.Seek(10999)
+		require.Equal(t, chunkenc.ValFloat, res)
+		require.NoError(t, it.Err())
+
+		ts, v = it.At()
+		require.Equal(t, int64(11000), ts)
+		require.Equal(t, float64(3), v)
+
+		// Attempt to seek to something past the last sample (should return false and exhaust the iterator).
+		res = it.Seek(99999)
+		require.Equal(t, chunkenc.ValNone, res)
+		require.NoError(t, it.Err())
+
+		// Attempt to next past the last sample (should return false as the iterator is exhausted).
+		res = it.Next()
+		require.Equal(t, chunkenc.ValNone, res)
+		require.NoError(t, it.Err())
+	})
+
+	t.Run("invalid chunk encoding error", func(t *testing.T) {
+		chks := buildTestChunks(t)
+
+		// Set chunk type to an invalid value.
+		chks[0].Type = 8
+
+		it := newChunkedSeriesIterator(chks, 0, 14000)
+
+		res := it.Next()
+		require.Equal(t, chunkenc.ValNone, res)
+
+		res = it.Seek(1000)
+		require.Equal(t, chunkenc.ValNone, res)
+
+		require.ErrorContains(t, it.err, "invalid chunk encoding")
+		require.Nil(t, it.cur)
+	})
+
+	t.Run("empty chunks", func(t *testing.T) {
+		emptyChunks := make([]prompb.Chunk, 0)
+
+		it1 := newChunkedSeriesIterator(emptyChunks, 0, 1000)
+		require.Equal(t, chunkenc.ValNone, it1.Next())
+		require.Equal(t, chunkenc.ValNone, it1.Seek(1000))
+		require.NoError(t, it1.Err())
+
+		var nilChunks []prompb.Chunk
+
+		it2 := newChunkedSeriesIterator(nilChunks, 0, 1000)
+		require.Equal(t, chunkenc.ValNone, it2.Next())
+		require.Equal(t, chunkenc.ValNone, it2.Seek(1000))
+		require.NoError(t, it2.Err())
+	})
+}
+
+func TestChunkedSeries(t *testing.T) {
+	t.Run("happy path", func(t *testing.T) {
+		chks := buildTestChunks(t)
+
+		s := chunkedSeries{
+			ChunkedSeries: prompb.ChunkedSeries{
+				Labels: []prompb.Label{
+					{Name: "foo", Value: "bar"},
+					{Name: "asdf", Value: "zxcv"},
+				},
+				Chunks: chks,
+			},
+		}
+
+		require.Equal(t, labels.FromStrings("asdf", "zxcv", "foo", "bar"), s.Labels())
+
+		it := s.Iterator(nil)
+		res := it.Next() // Behavior is undefined w/o the initial call to Next.
+
+		require.Equal(t, chunkenc.ValFloat, res)
+		require.NoError(t, it.Err())
+
+		ts, v := it.At()
+		require.Equal(t, int64(0), ts)
+		require.Equal(t, float64(0), v)
+	})
+}
+
+func TestChunkedSeriesSet(t *testing.T) {
+	t.Run("happy path", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		flusher := &mockFlusher{}
+
+		w := NewChunkedWriter(buf, flusher)
+		r := NewChunkedReader(buf, config.DefaultChunkedReadLimit, nil)
+
+		chks := buildTestChunks(t)
+		l := []prompb.Label{
+			{Name: "foo", Value: "bar"},
+		}
+
+		for i, c := range chks {
+			cSeries := prompb.ChunkedSeries{Labels: l, Chunks: []prompb.Chunk{c}}
+			readResp := prompb.ChunkedReadResponse{
+				ChunkedSeries: []*prompb.ChunkedSeries{&cSeries},
+				QueryIndex:    int64(i),
+			}
+
+			b, err := proto.Marshal(&readResp)
+			require.NoError(t, err)
+
+			_, err = w.Write(b)
+			require.NoError(t, err)
+		}
+
+		ss := NewChunkedSeriesSet(r, io.NopCloser(buf), 0, 14000, func(error) {})
+		require.NoError(t, ss.Err())
+		require.Nil(t, ss.Warnings())
+
+		res := ss.Next()
+		require.True(t, res)
+		require.NoError(t, ss.Err())
+
+		s := ss.At()
+		require.Equal(t, 1, s.Labels().Len())
+		require.True(t, s.Labels().Has("foo"))
+		require.Equal(t, "bar", s.Labels().Get("foo"))
+
+		it := s.Iterator(nil)
+		it.Next()
+		ts, v := it.At()
+		require.Equal(t, int64(0), ts)
+		require.Equal(t, float64(0), v)
+
+		numResponses := 1
+		for ss.Next() {
+			numResponses++
+		}
+		require.Equal(t, numTestChunks, numResponses)
+		require.NoError(t, ss.Err())
+	})
+
+	t.Run("chunked reader error", func(t *testing.T) {
+		buf := &bytes.Buffer{}
+		flusher := &mockFlusher{}
+
+		w := NewChunkedWriter(buf, flusher)
+		r := NewChunkedReader(buf, config.DefaultChunkedReadLimit, nil)
+
+		chks := buildTestChunks(t)
+		l := []prompb.Label{
+			{Name: "foo", Value: "bar"},
+		}
+
+		for i, c := range chks {
+			cSeries := prompb.ChunkedSeries{Labels: l, Chunks: []prompb.Chunk{c}}
+			readResp := prompb.ChunkedReadResponse{
+				ChunkedSeries: []*prompb.ChunkedSeries{&cSeries},
+				QueryIndex:    int64(i),
+			}
+
+			b, err := proto.Marshal(&readResp)
+			require.NoError(t, err)
+
+			b[0] = 0xFF // Corruption!
+
+			_, err = w.Write(b)
+			require.NoError(t, err)
+		}
+
+		ss := NewChunkedSeriesSet(r, io.NopCloser(buf), 0, 14000, func(error) {})
+		require.NoError(t, ss.Err())
+		require.Nil(t, ss.Warnings())
+
+		res := ss.Next()
+		require.False(t, res)
+		require.ErrorContains(t, ss.Err(), "proto: illegal wireType 7")
+	})
+}
+
+// mockFlusher implements http.Flusher.
+type mockFlusher struct{}
+
+func (f *mockFlusher) Flush() {}
+
+const (
+	numTestChunks          = 3
+	numSamplesPerTestChunk = 5
+)
+
+func buildTestChunks(t *testing.T) []prompb.Chunk {
+	startTime := int64(0)
+	chks := make([]prompb.Chunk, 0, numTestChunks)
+
+	time := startTime
+
+	for i := 0; i < numTestChunks; i++ {
+		c := chunkenc.NewXORChunk()
+
+		a, err := c.Appender()
+		require.NoError(t, err)
+
+		minTimeMs := time
+
+		for j := 0; j < numSamplesPerTestChunk; j++ {
+			a.Append(time, float64(i+j))
+			time += int64(1000)
+		}
+
+		chks = append(chks, prompb.Chunk{
+			MinTimeMs: minTimeMs,
+			MaxTimeMs: time,
+			Type:      prompb.Chunk_XOR,
+			Data:      c.Bytes(),
+		})
+	}
+
+	return chks
+}

storage/remote/read.go

@@ -165,11 +165,11 @@ func (q *querier) Select(ctx context.Context, sortSeries bool, hints *storage.Se
 		return storage.ErrSeriesSet(fmt.Errorf("toQuery: %w", err))
 	}
 
-	res, err := q.client.Read(ctx, query)
+	res, err := q.client.Read(ctx, query, sortSeries)
 	if err != nil {
 		return storage.ErrSeriesSet(fmt.Errorf("remote_read: %w", err))
 	}
-	return newSeriesSetFilter(FromQueryResult(sortSeries, res), added)
+	return newSeriesSetFilter(res, added)
 }
 
 // addExternalLabels adds matchers for each external label. External labels

storage/remote/read_handler_test.go

@@ -179,7 +179,7 @@ func BenchmarkStreamReadEndpoint(b *testing.B) {
 		require.Equal(b, 2, recorder.Code/100)
 
 		var results []*prompb.ChunkedReadResponse
-		stream := NewChunkedReader(recorder.Result().Body, DefaultChunkedReadLimit, nil)
+		stream := NewChunkedReader(recorder.Result().Body, config.DefaultChunkedReadLimit, nil)
 
 		for {
 			res := &prompb.ChunkedReadResponse{}
@@ -280,7 +280,7 @@ func TestStreamReadEndpoint(t *testing.T) {
 	require.Equal(t, "", recorder.Result().Header.Get("Content-Encoding"))
 
 	var results []*prompb.ChunkedReadResponse
-	stream := NewChunkedReader(recorder.Result().Body, DefaultChunkedReadLimit, nil)
+	stream := NewChunkedReader(recorder.Result().Body, config.DefaultChunkedReadLimit, nil)
 	for {
 		res := &prompb.ChunkedReadResponse{}
 		err := stream.NextProto(res)

storage/remote/read_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/prometheus/prometheus/config"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/prompb"
+	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/util/annotations"
 	"github.com/prometheus/prometheus/util/testutil"
 )
@@ -198,7 +199,7 @@ type mockedRemoteClient struct {
 	b     labels.ScratchBuilder
 }
 
-func (c *mockedRemoteClient) Read(_ context.Context, query *prompb.Query) (*prompb.QueryResult, error) {
+func (c *mockedRemoteClient) Read(_ context.Context, query *prompb.Query, sortSeries bool) (storage.SeriesSet, error) {
 	if c.got != nil {
 		return nil, fmt.Errorf("expected only one call to remote client got: %v", query)
 	}
@@ -227,7 +228,7 @@ func (c *mockedRemoteClient) Read(_ context.Context, query *prompb.Query) (*prom
 			q.Timeseries = append(q.Timeseries, &prompb.TimeSeries{Labels: s.Labels})
 		}
 	}
-	return q, nil
+	return FromQueryResult(sortSeries, q), nil
 }
 
 func (c *mockedRemoteClient) reset() {

storage/remote/storage.go

@@ -115,6 +115,7 @@ func (s *Storage) ApplyConfig(conf *config.Config) error {
 		c, err := NewReadClient(name, &ClientConfig{
 			URL:              rrConf.URL,
 			Timeout:          rrConf.RemoteTimeout,
+			ChunkedReadLimit: rrConf.ChunkedReadLimit,
 			HTTPClientConfig: rrConf.HTTPClientConfig,
 			Headers:          rrConf.Headers,
 		})

web/api/v1/api_test.go

@@ -1074,6 +1074,9 @@ func setupRemote(s storage.Storage) *httptest.Server {
 			}
 		}
 
+		w.Header().Set("Content-Type", "application/x-protobuf")
+		w.Header().Set("Content-Encoding", "snappy")
+
 		if err := remote.EncodeReadResponse(&resp, w); err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return