enable channelz config

Signed-off-by: yeya24 <benye@amazon.com>

Author: yeya24

go.mod

@@ -23,6 +23,8 @@ require (
 	github.com/pmezard/go-difflib v1.0.0
 	github.com/prometheus/client_golang v1.15.1
 	github.com/prometheus/exporter-toolkit v0.8.2
+	github.com/rantav/go-grpc-channelz v0.0.4
+	github.com/sercand/kuberesolver/v5 v5.1.1
 	github.com/sirupsen/logrus v1.6.0
 	github.com/soheilhy/cmux v0.1.5
 	github.com/stretchr/testify v1.8.1
@@ -41,6 +43,7 @@ require (
 	github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd // indirect
 	github.com/coreos/go-systemd/v22 v22.4.0 // indirect
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
+	github.com/go-chi/chi/v5 v5.0.7 // indirect
 	github.com/go-logfmt/logfmt v0.5.1 // indirect
 	github.com/jpillora/backoff v1.0.0 // indirect
 	github.com/konsorten/go-windows-terminal-sequences v1.0.3 // indirect
@@ -53,7 +56,6 @@ require (
 	github.com/prometheus/common v0.42.0 // indirect
 	github.com/prometheus/procfs v0.9.0 // indirect
 	github.com/rogpeppe/go-internal v1.13.1 // indirect
-	github.com/sercand/kuberesolver/v5 v5.1.1 // indirect
 	go.uber.org/atomic v1.5.1 // indirect
 	golang.org/x/crypto v0.29.0 // indirect
 	golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 // indirect

go.sum

@@ -17,6 +17,8 @@ github.com/felixge/httpsnoop v1.0.3 h1:s/nj+GCswXYzN5v2DpNMuMQYe+0DDwt5WVCU6CWBd
 github.com/felixge/httpsnoop v1.0.3/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
 github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
+github.com/go-chi/chi/v5 v5.0.7 h1:rDTPXLDHGATaeHvVlLcR4Qe0zftYethFucbjVQ1PxU8=
+github.com/go-chi/chi/v5 v5.0.7/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
 github.com/go-kit/log v0.2.1 h1:MRVx0/zhvdseW+Gza6N9rVzU/IVzaeE1SFI4raAhmBU=
 github.com/go-kit/log v0.2.1/go.mod h1:NwTd00d/i8cPZ3xOwwiv2PO5MOcx78fFErGNcVmBjv0=
 github.com/go-logfmt/logfmt v0.5.1 h1:otpy5pqBCBZ1ng9RQ0dPu4PN7ba75Y/aA+UpowDyNVA=
@@ -79,6 +81,8 @@ github.com/prometheus/exporter-toolkit v0.8.2 h1:sbJAfBXQFkG6sUkbwBun8MNdzW9+wd5
 github.com/prometheus/exporter-toolkit v0.8.2/go.mod h1:00shzmJL7KxcsabLWcONwpyNEuWhREOnFqZW7vadFS0=
 github.com/prometheus/procfs v0.9.0 h1:wzCHvIvM5SxWqYvwgVL7yJY8Lz3PKn49KQtpgMYJfhI=
 github.com/prometheus/procfs v0.9.0/go.mod h1:+pB4zwohETzFnmlpe6yd2lSc+0/46IYZRB/chUwxUZY=
+github.com/rantav/go-grpc-channelz v0.0.4 h1:8GvqhA6siQVBsZYzal3yHhyJ9YiHEJx7RtSH2Jvm9Co=
+github.com/rantav/go-grpc-channelz v0.0.4/go.mod h1:HodrRmnnH1zXcEEfK7EJrI23YMPMT7uvyAYkq2JUIcI=
 github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
 github.com/sercand/kuberesolver/v5 v5.1.1 h1:CYH+d67G0sGBj7q5wLK61yzqJJ8gLLC8aeprPTHb6yY=

server/server.go

@@ -17,10 +17,12 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/exporter-toolkit/web"
+	channelz "github.com/rantav/go-grpc-channelz"
 	"github.com/soheilhy/cmux"
 	"golang.org/x/net/context"
 	"golang.org/x/net/netutil"
 	"google.golang.org/grpc"
+	channelzservice "google.golang.org/grpc/channelz/service"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
 
@@ -110,6 +112,8 @@ type Config struct {
 	GRPCServerMinTimeBetweenPings      time.Duration `yaml:"grpc_server_min_time_between_pings"`
 	GRPCServerPingWithoutStreamAllowed bool          `yaml:"grpc_server_ping_without_stream_allowed"`
 
+	EnableChannelz bool `yaml:"enable_channelz"`
+
 	LogFormat                    logging.Format    `yaml:"log_format"`
 	LogLevel                     logging.Level     `yaml:"log_level"`
 	Log                          logging.Interface `yaml:"-"`
@@ -168,6 +172,7 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.DurationVar(&cfg.GRPCServerTimeout, "server.grpc.keepalive.timeout", time.Second*20, "After having pinged for keepalive check, the duration after which an idle connection should be closed, Default: 20s")
 	f.DurationVar(&cfg.GRPCServerMinTimeBetweenPings, "server.grpc.keepalive.min-time-between-pings", 5*time.Minute, "Minimum amount of time a client should wait before sending a keepalive ping. If client sends keepalive ping more often, server will send GOAWAY and close the connection.")
 	f.BoolVar(&cfg.GRPCServerPingWithoutStreamAllowed, "server.grpc.keepalive.ping-without-stream-allowed", false, "If true, server allows keepalive pings even when there are no active streams(RPCs). If false, and client sends ping when there are no active streams, server will send GOAWAY and close the connection.")
+	f.BoolVar(&cfg.EnableChannelz, "server.enable-channelz", false, "Enable Channelz for gRPC server. A web UI will be also exposed on the HTTP server at /channelz")
 	f.StringVar(&cfg.PathPrefix, "server.path-prefix", "", "Base path to serve all API routes from (e.g. /v1/)")
 	cfg.LogFormat.RegisterFlags(f)
 	cfg.LogLevel.RegisterFlags(f)
@@ -376,6 +381,12 @@ func newServer(cfg Config, metrics *Metrics) (*Server, error) {
 	grpcServer := grpc.NewServer(grpcOptions...)
 	grpcOnHttpServer := grpc.NewServer(grpcOptions...)
 
+	// Register channelz service if enabled
+	if cfg.EnableChannelz {
+		channelzservice.RegisterChannelzServiceToServer(grpcServer)
+		channelzservice.RegisterChannelzServiceToServer(grpcOnHttpServer)
+	}
+
 	// Setup HTTP server
 	var router *mux.Router
 	if cfg.Router != nil {
@@ -392,6 +403,13 @@ func newServer(cfg Config, metrics *Metrics) (*Server, error) {
 		RegisterInstrumentationWithGatherer(router, gatherer)
 	}
 
+	// Register channelz web UI if enabled
+	if cfg.EnableChannelz {
+		// Mount channelz handler at /channelz
+		grpcAddr := fmt.Sprintf("%s:%d", cfg.GRPCListenAddress, cfg.GRPCListenPort)
+		router.PathPrefix("/channelz").Handler(channelz.CreateHandler("/", grpcAddr))
+	}
+
 	var sourceIPs *middleware.SourceIPExtractor
 	if cfg.LogSourceIPs {
 		sourceIPs, err = middleware.NewSourceIPs(cfg.LogSourceIPsHeader, cfg.LogSourceIPsRegex)