From 5afcd3921471c51a9bd03c1486492ccea7997fa3 Mon Sep 17 00:00:00 2001
From: Gyuho Lee <leegyuho@amazon.com>
Date: Wed, 18 Mar 2020 16:12:55 -0700
Subject: [PATCH] etcdserver/api/v3rpc: handle api version metadata, add
 metrics

ref.
https://github.com/etcd-io/etcd/pull/11687

Signed-off-by: Gyuho Lee <leegyuho@amazon.com>
---
 etcdserver/api/v3rpc/interceptor.go | 22 +++++++++++++++++++---
 etcdserver/api/v3rpc/metrics.go     | 10 ++++++++++
 etcdserver/api/v3rpc/rpctypes/md.go |  2 ++
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/etcdserver/api/v3rpc/interceptor.go b/etcdserver/api/v3rpc/interceptor.go
index d594ae7f154c..fbc2ba3ed8b9 100644
--- a/etcdserver/api/v3rpc/interceptor.go
+++ b/etcdserver/api/v3rpc/interceptor.go
@@ -16,16 +16,16 @@ package v3rpc
 
 import (
 	"context"
+	"strings"
 	"sync"
 	"time"
 
 	"github.com/coreos/etcd/etcdserver"
 	"github.com/coreos/etcd/etcdserver/api"
 	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"github.com/coreos/etcd/pkg/types"
 	"github.com/coreos/etcd/raft"
-
-	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"go.uber.org/zap"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
@@ -49,6 +49,12 @@ func newUnaryInterceptor(s *etcdserver.EtcdServer) grpc.UnaryServerInterceptor {
 
 		md, ok := metadata.FromIncomingContext(ctx)
 		if ok {
+			ver, vs := "unknown", metadataGet(md, rpctypes.MetadataClientAPIVersionKey)
+			if len(vs) > 0 {
+				ver = vs[0]
+			}
+			clientRequests.WithLabelValues("unary", ver).Inc()
+
 			if ks := md[rpctypes.MetadataRequireLeaderKey]; len(ks) > 0 && ks[0] == rpctypes.MetadataHasLeader {
 				if s.Leader() == types.ID(raft.None) {
 					return nil, rpctypes.ErrGRPCNoLeader
@@ -187,6 +193,12 @@ func newStreamInterceptor(s *etcdserver.EtcdServer) grpc.StreamServerInterceptor
 
 		md, ok := metadata.FromIncomingContext(ss.Context())
 		if ok {
+			ver, vs := "unknown", metadataGet(md, rpctypes.MetadataClientAPIVersionKey)
+			if len(vs) > 0 {
+				ver = vs[0]
+			}
+			clientRequests.WithLabelValues("stream", ver).Inc()
+
 			if ks := md[rpctypes.MetadataRequireLeaderKey]; len(ks) > 0 && ks[0] == rpctypes.MetadataHasLeader {
 				if s.Leader() == types.ID(raft.None) {
 					return rpctypes.ErrGRPCNoLeader
@@ -205,7 +217,6 @@ func newStreamInterceptor(s *etcdserver.EtcdServer) grpc.StreamServerInterceptor
 					smap.mu.Unlock()
 					cancel()
 				}()
-
 			}
 		}
 
@@ -261,3 +272,8 @@ func monitorLeader(s *etcdserver.EtcdServer) *streamsMap {
 
 	return smap
 }
+
+func metadataGet(md metadata.MD, k string) []string {
+	k = strings.ToLower(k)
+	return md[k]
+}
diff --git a/etcdserver/api/v3rpc/metrics.go b/etcdserver/api/v3rpc/metrics.go
index 6cb41a61e565..46db8649c1c0 100644
--- a/etcdserver/api/v3rpc/metrics.go
+++ b/etcdserver/api/v3rpc/metrics.go
@@ -30,9 +30,19 @@ var (
 		Name:      "client_grpc_received_bytes_total",
 		Help:      "The total number of bytes received from grpc clients.",
 	})
+
+	clientRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "etcd",
+		Subsystem: "server",
+		Name:      "client_requests_total",
+		Help:      "The total number of client requests per client version.",
+	},
+		[]string{"type", "client_api_version"},
+	)
 )
 
 func init() {
 	prometheus.MustRegister(sentBytes)
 	prometheus.MustRegister(receivedBytes)
+	prometheus.MustRegister(clientRequests)
 }
diff --git a/etcdserver/api/v3rpc/rpctypes/md.go b/etcdserver/api/v3rpc/rpctypes/md.go
index 5c590e1aec99..90b8b835b168 100644
--- a/etcdserver/api/v3rpc/rpctypes/md.go
+++ b/etcdserver/api/v3rpc/rpctypes/md.go
@@ -17,4 +17,6 @@ package rpctypes
 var (
 	MetadataRequireLeaderKey = "hasleader"
 	MetadataHasLeader        = "true"
+
+	MetadataClientAPIVersionKey = "client-api-version"
 )