Method RemoteRead

integration/e2ecortex/client.go:566–629

RemoteRead runs a remote read query.

(matchers []*labels.Matcher, start, end time.Time, step time.Duration)

// RemoteRead runs a remote read query.
func (c *Client) RemoteRead(matchers []*labels.Matcher, start, end time.Time, step time.Duration) (*prompb.ReadResponse, error) {
	startMs := start.UnixMilli()
	endMs := end.UnixMilli()
	stepMs := step.Milliseconds()

	q, err := remote.ToQuery(startMs, endMs, matchers, &storage.SelectHints{
		Step:  stepMs,
		Start: startMs,
		End:   endMs,
	})
	if err != nil {
		return nil, err
	}

	req := &prompb.ReadRequest{
		Queries:               []*prompb.Query{q},
		AcceptedResponseTypes: []prompb.ReadRequest_ResponseType{prompb.ReadRequest_STREAMED_XOR_CHUNKS},
	}

	data, err := proto.Marshal(req)
	if err != nil {
		return nil, err
	}
	compressed := snappy.Encode(nil, data)

	// Call the remote read API endpoint with a timeout.
	httpReqCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	httpReq, err := http.NewRequestWithContext(httpReqCtx, "POST", "http://"+c.querierAddress+"/prometheus/api/v1/read", bytes.NewReader(compressed))
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("X-Scope-OrgID", "user-1")
	httpReq.Header.Add("Content-Encoding", "snappy")
	httpReq.Header.Add("Accept-Encoding", "snappy")
	httpReq.Header.Set("Content-Type", "application/x-protobuf")
	httpReq.Header.Set("User-Agent", "Prometheus/1.8.2")
	httpReq.Header.Set("X-Prometheus-Remote-Read-Version", "0.1.0")

	httpResp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return nil, err
	}
	if httpResp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("unexpected status code %d", httpResp.StatusCode)
	}

	compressed, err = io.ReadAll(httpResp.Body)
	if err != nil {
		return nil, err
	}

	uncompressed, err := snappy.Decode(nil, compressed)
	if err != nil {
		return nil, err
	}