diff --git a/CHANGELOG-3.4.md b/CHANGELOG-3.4.md
index 6b8435effb6..dc6d3881419 100644
--- a/CHANGELOG-3.4.md
+++ b/CHANGELOG-3.4.md
@@ -191,6 +191,11 @@ See [security doc](https://github.com/coreos/etcd/blob/master/Documentation/op-g
 - Rename [**`embed.Config.LogOutput`** to **`embed.Config.LogOutputs`**](https://github.com/coreos/etcd/pull/9624) to support multiple log outputs.
 - Change [**`embed.Config.LogOutputs`** type from `string` to `[]string`](https://github.com/coreos/etcd/pull/9579) to support multiple log outputs.
 
+### Package `integration`
+
+- Add [`CLUSTER_DEBUG` to enable test cluster logging](https://github.com/coreos/etcd/pull/9678).
+  - Deprecated `capnslog` in integration tests.
+
 ### API
 
 - Add [`snapshot`](https://github.com/coreos/etcd/pull/9118) package for snapshot restore/save operations (see [`godoc.org/github.com/etcd/snapshot`](https://godoc.org/github.com/coreos/etcd/snapshot) for more).
diff --git a/clientv3/integration/logger_test.go b/clientv3/integration/logger_test.go
index bc0220db4b7..48da6e8bdcc 100644
--- a/clientv3/integration/logger_test.go
+++ b/clientv3/integration/logger_test.go
@@ -19,11 +19,9 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 
-	"github.com/coreos/pkg/capnslog"
 	"google.golang.org/grpc/grpclog"
 )
 
 func init() {
-	capnslog.SetGlobalLogLevel(capnslog.CRITICAL)
 	clientv3.SetLogger(grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard))
 }
diff --git a/clientv3/ordering/logger_test.go b/clientv3/ordering/logger_test.go
index 986c54148ad..798172ec211 100644
--- a/clientv3/ordering/logger_test.go
+++ b/clientv3/ordering/logger_test.go
@@ -19,11 +19,9 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 
-	"github.com/coreos/pkg/capnslog"
 	"google.golang.org/grpc/grpclog"
 )
 
 func init() {
-	capnslog.SetGlobalLogLevel(capnslog.CRITICAL)
 	clientv3.SetLogger(grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard))
 }
diff --git a/etcdserver/api/v3rpc/watch.go b/etcdserver/api/v3rpc/watch.go
index 643d1dab94e..5a1f621cc2d 100644
--- a/etcdserver/api/v3rpc/watch.go
+++ b/etcdserver/api/v3rpc/watch.go
@@ -159,7 +159,7 @@ func (ws *watchServer) Watch(stream pb.Watch_WatchServer) (err error) {
 		if rerr := sws.recvLoop(); rerr != nil {
 			if isClientCtxErr(stream.Context().Err(), rerr) {
 				if sws.lg != nil {
-					sws.lg.Debug("failed to receive watch request from gRPC stream", zap.Error(err))
+					sws.lg.Debug("failed to receive watch request from gRPC stream", zap.Error(rerr))
 				} else {
 					plog.Debugf("failed to receive watch request from gRPC stream (%q)", rerr.Error())
 				}
diff --git a/etcdserver/v2store/store_v2v3_test.go b/etcdserver/v2store/store_v2v3_test.go
index 8232ce09a30..4d2703c40fb 100644
--- a/etcdserver/v2store/store_v2v3_test.go
+++ b/etcdserver/v2store/store_v2v3_test.go
@@ -25,12 +25,10 @@ import (
 	"github.com/coreos/etcd/etcdserver/v2store"
 	"github.com/coreos/etcd/integration"
 
-	"github.com/coreos/pkg/capnslog"
 	"google.golang.org/grpc/grpclog"
 )
 
 func init() {
-	capnslog.SetGlobalLogLevel(capnslog.CRITICAL)
 	clientv3.SetLogger(grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard))
 }
 
diff --git a/integration/cluster.go b/integration/cluster.go
index e872e552106..81f47cf72a2 100644
--- a/integration/cluster.go
+++ b/integration/cluster.go
@@ -51,8 +51,8 @@ import (
 	"github.com/coreos/etcd/pkg/types"
 	"github.com/coreos/etcd/rafthttp"
 
-	"github.com/coreos/pkg/capnslog"
 	"github.com/soheilhy/cmux"
+	"go.uber.org/zap"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/keepalive"
@@ -105,9 +105,15 @@ var (
 		ClientCertAuth: true,
 	}
 
-	plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "integration")
+	lg = zap.NewNop()
 )
 
+func init() {
+	if os.Getenv("CLUSTER_DEBUG") != "" {
+		lg, _ = zap.NewProduction()
+	}
+}
+
 type ClusterConfig struct {
 	Size                  int
 	PeerTLS               *transport.TLSInfo
@@ -626,6 +632,27 @@ func mustNewMember(t *testing.T, mcfg memberConfig) *member {
 
 	m.InitialCorruptCheck = true
 
+	m.LoggerConfig = &zap.Config{
+		Level:       zap.NewAtomicLevelAt(zap.InfoLevel),
+		Development: false,
+		Sampling: &zap.SamplingConfig{
+			Initial:    100,
+			Thereafter: 100,
+		},
+		Encoding:      "json",
+		EncoderConfig: zap.NewProductionEncoderConfig(),
+
+		OutputPaths:      []string{"/dev/null"},
+		ErrorOutputPaths: []string{"/dev/null"},
+	}
+	if os.Getenv("CLUSTER_DEBUG") != "" {
+		m.LoggerConfig.OutputPaths = []string{"stderr"}
+		m.LoggerConfig.ErrorOutputPaths = []string{"stderr"}
+	}
+	m.Logger, err = m.LoggerConfig.Build()
+	if err != nil {
+		t.Fatal(err)
+	}
 	return m
 }
 
@@ -633,7 +660,7 @@ func mustNewMember(t *testing.T, mcfg memberConfig) *member {
 func (m *member) listenGRPC() error {
 	// prefix with localhost so cert has right domain
 	m.grpcAddr = "localhost:" + m.Name
-	if m.useIP { // for IP-only sTLS certs
+	if m.useIP { // for IP-only TLS certs
 		m.grpcAddr = "127.0.0.1:" + m.Name
 	}
 	l, err := transport.NewUnixListener(m.grpcAddr)
@@ -720,7 +747,13 @@ func (m *member) Clone(t *testing.T) *member {
 // Launch starts a member based on ServerConfig, PeerListeners
 // and ClientListeners.
 func (m *member) Launch() error {
-	plog.Printf("launching %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"launching a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 	var err error
 	if m.s, err = etcdserver.NewServer(m.ServerConfig); err != nil {
 		return fmt.Errorf("failed to initialize the etcd server: %v", err)
@@ -860,7 +893,13 @@ func (m *member) Launch() error {
 		m.serverClosers = append(m.serverClosers, closer)
 	}
 
-	plog.Printf("launched %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"launched a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 	return nil
 }
 
@@ -920,10 +959,22 @@ func (m *member) Close() {
 
 // Stop stops the member, but the data dir of the member is preserved.
 func (m *member) Stop(t *testing.T) {
-	plog.Printf("stopping %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"stopping a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 	m.Close()
 	m.serverClosers = nil
-	plog.Printf("stopped %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"stopped a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 }
 
 // checkLeaderTransition waits for leader transition, returning the new leader ID.
@@ -942,7 +993,13 @@ func (m *member) StopNotify() <-chan struct{} {
 
 // Restart starts the member using the preserved data dir.
 func (m *member) Restart(t *testing.T) error {
-	plog.Printf("restarting %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"restarting a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 	newPeerListeners := make([]net.Listener, 0)
 	for _, ln := range m.PeerListeners {
 		newPeerListeners = append(newPeerListeners, NewListenerWithAddr(t, ln.Addr().String()))
@@ -961,20 +1018,39 @@ func (m *member) Restart(t *testing.T) error {
 	}
 
 	err := m.Launch()
-	plog.Printf("restarted %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"restarted a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+		zap.Error(err),
+	)
 	return err
 }
 
 // Terminate stops the member and removes the data dir.
 func (m *member) Terminate(t *testing.T) {
-	plog.Printf("terminating %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"terminating a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 	m.Close()
 	if !m.keepDataDirTerminate {
 		if err := os.RemoveAll(m.ServerConfig.DataDir); err != nil {
 			t.Fatal(err)
 		}
 	}
-	plog.Printf("terminated %s (%s)", m.Name, m.grpcAddr)
+	lg.Info(
+		"terminated a member",
+		zap.String("name", m.Name),
+		zap.Strings("advertise-peer-urls", m.PeerURLs.StringSlice()),
+		zap.Strings("listen-client-urls", m.ClientURLs.StringSlice()),
+		zap.String("grpc-address", m.grpcAddr),
+	)
 }
 
 // Metric gets the metric value for a member
diff --git a/integration/logger_test.go b/integration/logger_test.go
index 7c6fc424875..48da6e8bdcc 100644
--- a/integration/logger_test.go
+++ b/integration/logger_test.go
@@ -19,13 +19,9 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 
-	"github.com/coreos/pkg/capnslog"
 	"google.golang.org/grpc/grpclog"
 )
 
-const defaultLogLevel = capnslog.CRITICAL
-
 func init() {
-	capnslog.SetGlobalLogLevel(defaultLogLevel)
 	clientv3.SetLogger(grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard))
 }