PRW2: use client-golang codes (#7027)

Signed-off-by: SungJin1212 <tjdwls1201@gmail.com>

Author: SungJin1212

go.mod

@@ -88,6 +88,7 @@ require (
 	github.com/oklog/ulid/v2 v2.1.1
 	github.com/parquet-go/parquet-go v0.25.1
 	github.com/prometheus-community/parquet-common v0.0.0-20250827225610-65f0b68d35e6
+	github.com/prometheus/client_golang/exp v0.0.0-20250914183048-a974e0d45e0a
 	github.com/prometheus/procfs v0.16.1
 	github.com/sercand/kuberesolver/v5 v5.1.1
 	github.com/tjhop/slog-gokit v0.1.4

go.sum

@@ -1631,6 +1631,8 @@ github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP
 github.com/prometheus/client_golang v1.11.1/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
 github.com/prometheus/client_golang v1.23.0-rc.1 h1:Is/nGODd8OsJlNQSybeYBwY/B6aHrN7+QwVUYutHSgw=
 github.com/prometheus/client_golang v1.23.0-rc.1/go.mod h1:i/o0R9ByOnHX0McrTMTyhYvKE4haaf2mW08I+jGAjEE=
+github.com/prometheus/client_golang/exp v0.0.0-20250914183048-a974e0d45e0a h1:RF1vfKM34/3DbGNis22BGd6sDDY3XBi0eM7pYqmOEO0=
+github.com/prometheus/client_golang/exp v0.0.0-20250914183048-a974e0d45e0a/go.mod h1:FGJuwvfcPY0V5enm+w8zF1RNS062yugQtPPQp1c4Io4=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=

pkg/util/push/push.go

@@ -5,10 +5,9 @@ import (
 	"fmt"
 	"net/http"
 	"strconv"
-	"strings"
 
 	"github.com/go-kit/log/level"
-	"github.com/prometheus/prometheus/config"
+	"github.com/prometheus/client_golang/exp/api/remote"
 	"github.com/prometheus/prometheus/model/labels"
 	writev2 "github.com/prometheus/prometheus/prompb/io/prometheus/write/v2"
 	"github.com/prometheus/prometheus/util/compression"
@@ -125,14 +124,14 @@ func Handler(remoteWrite2Enabled bool, maxRecvMsgSize int, sourceIPs *middleware
 				contentType = appProtoContentType
 			}
 
-			msgType, err := parseProtoMsg(contentType)
+			msgType, err := remote.ParseProtoMsg(contentType)
 			if err != nil {
 				level.Error(logger).Log("Error decoding remote write request", "err", err)
 				http.Error(w, err.Error(), http.StatusUnsupportedMediaType)
 				return
 			}
 
-			if msgType != config.RemoteWriteProtoMsgV1 && msgType != config.RemoteWriteProtoMsgV2 {
+			if msgType != remote.WriteV1MessageType && msgType != remote.WriteV2MessageType {
 				level.Error(logger).Log("Not accepted msg type", "msgType", msgType, "err", err)
 				http.Error(w, err.Error(), http.StatusUnsupportedMediaType)
 				return
@@ -148,9 +147,9 @@ func Handler(remoteWrite2Enabled bool, maxRecvMsgSize int, sourceIPs *middleware
 			}
 
 			switch msgType {
-			case config.RemoteWriteProtoMsgV1:
+			case remote.WriteV1MessageType:
 				handlePRW1()
-			case config.RemoteWriteProtoMsgV2:
+			case remote.WriteV2MessageType:
 				handlePRW2()
 			}
 		} else {
@@ -165,32 +164,6 @@ func setPRW2RespHeader(w http.ResponseWriter, samples, histograms, exemplars int
 	w.Header().Set(rw20WrittenExemplarsHeader, strconv.FormatInt(exemplars, 10))
 }
 
-// Refer to parseProtoMsg in https://github.com/prometheus/prometheus/blob/main/storage/remote/write_handler.go
-func parseProtoMsg(contentType string) (config.RemoteWriteProtoMsg, error) {
-	contentType = strings.TrimSpace(contentType)
-
-	parts := strings.Split(contentType, ";")
-	if parts[0] != appProtoContentType {
-		return "", fmt.Errorf("expected %v as the first (media) part, got %v content-type", appProtoContentType, contentType)
-	}
-	// Parse potential https://www.rfc-editor.org/rfc/rfc9110#parameter
-	for _, p := range parts[1:] {
-		pair := strings.Split(p, "=")
-		if len(pair) != 2 {
-			return "", fmt.Errorf("as per https://www.rfc-editor.org/rfc/rfc9110#parameter expected parameters to be key-values, got %v in %v content-type", p, contentType)
-		}
-		if pair[0] == "proto" {
-			ret := config.RemoteWriteProtoMsg(pair[1])
-			if err := ret.Validate(); err != nil {
-				return "", fmt.Errorf("got %v content type; %w", contentType, err)
-			}
-			return ret, nil
-		}
-	}
-	// No "proto=" parameter, assuming v1.
-	return config.RemoteWriteProtoMsgV1, nil
-}
-
 func convertV2RequestToV1(req *writev2.Request) (cortexpb.PreallocWriteRequest, error) {
 	var v1Req cortexpb.PreallocWriteRequest
 	v1Timeseries := make([]cortexpb.PreallocTimeseries, 0, len(req.Timeseries))