From 8cf430140aa644f5523f6c5245f7aad84eef1507 Mon Sep 17 00:00:00 2001
From: Paul Glass <pglass@hashicorp.com>
Date: Tue, 11 Oct 2022 17:00:32 -0500
Subject: [PATCH] gRPC server metrics (#14922)

* Move stats.go from grpc-internal to grpc-middleware
* Update grpc server metrics with server type label
* Add stats test to grpc-external
* Remove global metrics instance from grpc server tests
---
 .changelog/14922.txt                          |   3 +
 agent/agent.go                                |   5 +-
 agent/consul/server.go                        |   2 +-
 agent/consul/server_test.go                   |   2 +-
 agent/grpc-external/server.go                 |  15 ++-
 agent/grpc-external/stats_test.go             | 104 ++++++++++++++++++
 agent/grpc-internal/client.go                 |   4 +-
 agent/grpc-internal/client_test.go            |   2 +-
 agent/grpc-internal/handler.go                |  18 ++-
 agent/grpc-internal/handler_test.go           |   5 +-
 agent/grpc-internal/server_test.go            |  46 +-------
 .../services/subscribe/subscribe_test.go      |  13 ++-
 agent/grpc-internal/stats_test.go             |  95 ++++------------
 .../stats.go                                  |  26 +++--
 agent/grpc-middleware/testutil/fake_sink.go   |  50 +++++++++
 .../testutil/testservice/fake_service.go      |  43 ++++++++
 .../testutil}/testservice/simple.pb.binary.go |   2 +-
 .../testutil}/testservice/simple.pb.go        |   2 +-
 .../testutil}/testservice/simple.proto        |   0
 agent/rpc/peering/service_test.go             |   2 +-
 agent/setup.go                                |  16 +--
 21 files changed, 305 insertions(+), 150 deletions(-)
 create mode 100644 .changelog/14922.txt
 create mode 100644 agent/grpc-external/stats_test.go
 rename agent/{grpc-internal => grpc-middleware}/stats.go (79%)
 create mode 100644 agent/grpc-middleware/testutil/fake_sink.go
 create mode 100644 agent/grpc-middleware/testutil/testservice/fake_service.go
 rename agent/{grpc-internal/internal => grpc-middleware/testutil}/testservice/simple.pb.binary.go (90%)
 rename agent/{grpc-internal/internal => grpc-middleware/testutil}/testservice/simple.pb.go (99%)
 rename agent/{grpc-internal/internal => grpc-middleware/testutil}/testservice/simple.proto (100%)

diff --git a/.changelog/14922.txt b/.changelog/14922.txt
new file mode 100644
index 000000000..e2f04991b
--- /dev/null
+++ b/.changelog/14922.txt
@@ -0,0 +1,3 @@
+```release-note:feature
+grpc: Added metrics for external gRPC server. Added `server_type=internal|external` label to gRPC metrics.
+```
diff --git a/agent/agent.go b/agent/agent.go
index 3de22c6ae..d0a1a2915 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -553,7 +553,10 @@ func (a *Agent) Start(ctx context.Context) error {
 
 	// This needs to happen after the initial auto-config is loaded, because TLS
 	// can only be configured on the gRPC server at the point of creation.
-	a.externalGRPCServer = external.NewServer(a.logger.Named("grpc.external"))
+	a.externalGRPCServer = external.NewServer(
+		a.logger.Named("grpc.external"),
+		metrics.Default(),
+	)
 
 	if err := a.startLicenseManager(ctx); err != nil {
 		return err
diff --git a/agent/consul/server.go b/agent/consul/server.go
index d6e412fe2..0972bab8d 100644
--- a/agent/consul/server.go
+++ b/agent/consul/server.go
@@ -845,7 +845,7 @@ func newGRPCHandlerFromConfig(deps Deps, config *Config, s *Server) connHandler
 		s.externalConnectCAServer.Register(srv)
 	}
 
-	return agentgrpc.NewHandler(deps.Logger, config.RPCAddr, register)
+	return agentgrpc.NewHandler(deps.Logger, config.RPCAddr, register, nil)
 }
 
 func (s *Server) connectCARootsMonitor(ctx context.Context) {
diff --git a/agent/consul/server_test.go b/agent/consul/server_test.go
index b9f8e7db9..c9b8a9324 100644
--- a/agent/consul/server_test.go
+++ b/agent/consul/server_test.go
@@ -328,7 +328,7 @@ func newServerWithDeps(t *testing.T, c *Config, deps Deps) (*Server, error) {
 			oldNotify()
 		}
 	}
-	grpcServer := external.NewServer(deps.Logger.Named("grpc.external"))
+	grpcServer := external.NewServer(deps.Logger.Named("grpc.external"), nil)
 	srv, err := NewServer(c, deps, grpcServer)
 	if err != nil {
 		return nil, err
diff --git a/agent/grpc-external/server.go b/agent/grpc-external/server.go
index 7ab72d77c..634205337 100644
--- a/agent/grpc-external/server.go
+++ b/agent/grpc-external/server.go
@@ -3,6 +3,7 @@ package external
 import (
 	"time"
 
+	"github.com/armon/go-metrics"
 	middleware "github.com/grpc-ecosystem/go-grpc-middleware"
 	recovery "github.com/grpc-ecosystem/go-grpc-middleware/recovery"
 	"google.golang.org/grpc"
@@ -11,13 +12,24 @@ import (
 	agentmiddleware "github.com/hashicorp/consul/agent/grpc-middleware"
 )
 
+var (
+	metricsLabels = []metrics.Label{{
+		Name:  "server_type",
+		Value: "external",
+	}}
+)
+
 // NewServer constructs a gRPC server for the external gRPC port, to which
 // handlers can be registered.
-func NewServer(logger agentmiddleware.Logger) *grpc.Server {
+func NewServer(logger agentmiddleware.Logger, metricsObj *metrics.Metrics) *grpc.Server {
+	if metricsObj == nil {
+		metricsObj = metrics.Default()
+	}
 	recoveryOpts := agentmiddleware.PanicHandlerMiddlewareOpts(logger)
 
 	opts := []grpc.ServerOption{
 		grpc.MaxConcurrentStreams(2048),
+		grpc.StatsHandler(agentmiddleware.NewStatsHandler(metricsObj, metricsLabels)),
 		middleware.WithUnaryServerChain(
 			// Add middlware interceptors to recover in case of panics.
 			recovery.UnaryServerInterceptor(recoveryOpts...),
@@ -25,6 +37,7 @@ func NewServer(logger agentmiddleware.Logger) *grpc.Server {
 		middleware.WithStreamServerChain(
 			// Add middlware interceptors to recover in case of panics.
 			recovery.StreamServerInterceptor(recoveryOpts...),
+			agentmiddleware.NewActiveStreamCounter(metricsObj, metricsLabels).Intercept,
 		),
 		grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
 			// This must be less than the keealive.ClientParameters Time setting, otherwise
diff --git a/agent/grpc-external/stats_test.go b/agent/grpc-external/stats_test.go
new file mode 100644
index 000000000..8f5dffb67
--- /dev/null
+++ b/agent/grpc-external/stats_test.go
@@ -0,0 +1,104 @@
+package external
+
+import (
+	"context"
+	"net"
+	"sort"
+	"testing"
+
+	"github.com/armon/go-metrics"
+	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
+	"google.golang.org/grpc"
+
+	"github.com/hashicorp/go-hclog"
+
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil"
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil/testservice"
+	"github.com/hashicorp/consul/proto/prototest"
+)
+
+func TestServer_EmitsStats(t *testing.T) {
+	sink, metricsObj := testutil.NewFakeSink(t)
+
+	srv := NewServer(hclog.Default(), metricsObj)
+
+	testservice.RegisterSimpleServer(srv, &testservice.Simple{})
+
+	lis, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	t.Cleanup(cancel)
+
+	g, ctx := errgroup.WithContext(ctx)
+	g.Go(func() error {
+		return srv.Serve(lis)
+	})
+	t.Cleanup(func() {
+		srv.Stop()
+		if err := g.Wait(); err != nil {
+			t.Logf("grpc server error: %v", err)
+		}
+	})
+
+	conn, err := grpc.DialContext(ctx, lis.Addr().String(), grpc.WithInsecure())
+	require.NoError(t, err)
+	t.Cleanup(func() { conn.Close() })
+
+	client := testservice.NewSimpleClient(conn)
+	fClient, err := client.Flow(ctx, &testservice.Req{Datacenter: "mine"})
+	require.NoError(t, err)
+
+	// Wait for the first event so that we know the stream is sending.
+	_, err = fClient.Recv()
+	require.NoError(t, err)
+
+	cancel()
+	conn.Close()
+	srv.GracefulStop()
+	// Wait for the server to stop so that active_streams is predictable.
+	require.NoError(t, g.Wait())
+
+	// Occasionally the active_stream=0 metric may be emitted before the
+	// active_conns=0 metric. The order of those metrics is not really important
+	// so we sort the calls to match the expected.
+	sort.Slice(sink.GaugeCalls, func(i, j int) bool {
+		if i < 2 || j < 2 {
+			return i < j
+		}
+		if len(sink.GaugeCalls[i].Key) < 4 || len(sink.GaugeCalls[j].Key) < 4 {
+			return i < j
+		}
+		return sink.GaugeCalls[i].Key[3] < sink.GaugeCalls[j].Key[3]
+	})
+
+	cmpMetricCalls := cmp.AllowUnexported(testutil.MetricCall{})
+	expLabels := []metrics.Label{{
+		Name:  "server_type",
+		Value: "external",
+	}}
+	expectedGauge := []testutil.MetricCall{
+		{Key: []string{"testing", "grpc", "server", "connections"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "streams"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "connections"}, Val: 0, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "streams"}, Val: 0, Labels: expLabels},
+	}
+	prototest.AssertDeepEqual(t, expectedGauge, sink.GaugeCalls, cmpMetricCalls)
+
+	expectedCounter := []testutil.MetricCall{
+		{Key: []string{"testing", "grpc", "server", "connection", "count"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "request", "count"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "stream", "count"}, Val: 1, Labels: expLabels},
+	}
+	prototest.AssertDeepEqual(t, expectedCounter, sink.IncrCounterCalls, cmpMetricCalls)
+}
+
+func logError(t *testing.T, f func() error) func() {
+	return func() {
+		if err := f(); err != nil {
+			t.Logf(err.Error())
+		}
+	}
+}
diff --git a/agent/grpc-internal/client.go b/agent/grpc-internal/client.go
index 451a5236e..711310538 100644
--- a/agent/grpc-internal/client.go
+++ b/agent/grpc-internal/client.go
@@ -10,6 +10,8 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/keepalive"
 
+	"github.com/armon/go-metrics"
+	agentmiddleware "github.com/hashicorp/consul/agent/grpc-middleware"
 	"github.com/hashicorp/consul/agent/metadata"
 	"github.com/hashicorp/consul/agent/pool"
 	"github.com/hashicorp/consul/tlsutil"
@@ -129,7 +131,7 @@ func (c *ClientConnPool) dial(datacenter string, serverType string) (*grpc.Clien
 		grpc.WithInsecure(),
 		grpc.WithContextDialer(c.dialer),
 		grpc.WithDisableRetry(),
-		grpc.WithStatsHandler(newStatsHandler(defaultMetrics())),
+		grpc.WithStatsHandler(agentmiddleware.NewStatsHandler(metrics.Default(), metricsLabels)),
 		// nolint:staticcheck // there is no other supported alternative to WithBalancerName
 		grpc.WithBalancerName("pick_first"),
 		// Keep alive parameters are based on the same default ones we used for
diff --git a/agent/grpc-internal/client_test.go b/agent/grpc-internal/client_test.go
index e36cd6aad..d9d264d80 100644
--- a/agent/grpc-internal/client_test.go
+++ b/agent/grpc-internal/client_test.go
@@ -14,8 +14,8 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/hashicorp/consul/agent/grpc-internal/internal/testservice"
 	"github.com/hashicorp/consul/agent/grpc-internal/resolver"
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil/testservice"
 	"github.com/hashicorp/consul/agent/metadata"
 	"github.com/hashicorp/consul/ipaddr"
 	"github.com/hashicorp/consul/sdk/freeport"
diff --git a/agent/grpc-internal/handler.go b/agent/grpc-internal/handler.go
index b5e7d2573..a576d656e 100644
--- a/agent/grpc-internal/handler.go
+++ b/agent/grpc-internal/handler.go
@@ -5,6 +5,7 @@ import (
 	"net"
 	"time"
 
+	"github.com/armon/go-metrics"
 	agentmiddleware "github.com/hashicorp/consul/agent/grpc-middleware"
 
 	middleware "github.com/grpc-ecosystem/go-grpc-middleware"
@@ -13,18 +14,27 @@ import (
 	"google.golang.org/grpc/keepalive"
 )
 
+var (
+	metricsLabels = []metrics.Label{{
+		Name:  "server_type",
+		Value: "internal",
+	}}
+)
+
 // NewHandler returns a gRPC server that accepts connections from Handle(conn).
 // The register function will be called with the grpc.Server to register
 // gRPC services with the server.
-func NewHandler(logger Logger, addr net.Addr, register func(server *grpc.Server)) *Handler {
-	metrics := defaultMetrics()
+func NewHandler(logger Logger, addr net.Addr, register func(server *grpc.Server), metricsObj *metrics.Metrics) *Handler {
+	if metricsObj == nil {
+		metricsObj = metrics.Default()
+	}
 
 	// We don't need to pass tls.Config to the server since it's multiplexed
 	// behind the RPC listener, which already has TLS configured.
 	recoveryOpts := agentmiddleware.PanicHandlerMiddlewareOpts(logger)
 
 	opts := []grpc.ServerOption{
-		grpc.StatsHandler(newStatsHandler(metrics)),
+		grpc.StatsHandler(agentmiddleware.NewStatsHandler(metricsObj, metricsLabels)),
 		middleware.WithUnaryServerChain(
 			// Add middlware interceptors to recover in case of panics.
 			recovery.UnaryServerInterceptor(recoveryOpts...),
@@ -32,7 +42,7 @@ func NewHandler(logger Logger, addr net.Addr, register func(server *grpc.Server)
 		middleware.WithStreamServerChain(
 			// Add middlware interceptors to recover in case of panics.
 			recovery.StreamServerInterceptor(recoveryOpts...),
-			(&activeStreamCounter{metrics: metrics}).Intercept,
+			agentmiddleware.NewActiveStreamCounter(metricsObj, metricsLabels).Intercept,
 		),
 		grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
 			MinTime: 15 * time.Second,
diff --git a/agent/grpc-internal/handler_test.go b/agent/grpc-internal/handler_test.go
index f53877301..4f093ac65 100644
--- a/agent/grpc-internal/handler_test.go
+++ b/agent/grpc-internal/handler_test.go
@@ -13,8 +13,8 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 
-	"github.com/hashicorp/consul/agent/grpc-internal/internal/testservice"
 	"github.com/hashicorp/consul/agent/grpc-internal/resolver"
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil/testservice"
 )
 
 func TestHandler_PanicRecoveryInterceptor(t *testing.T) {
@@ -57,5 +57,6 @@ func TestHandler_PanicRecoveryInterceptor(t *testing.T) {
 	// Checking the entire stack trace is not possible, let's
 	// make sure that it contains a couple of expected strings.
 	require.Contains(t, strLog, `[ERROR] panic serving grpc request: panic="panic from Something`)
-	require.Contains(t, strLog, `github.com/hashicorp/consul/agent/grpc-internal.(*simplePanic).Something`)
+	require.Contains(t, strLog, `github.com/hashicorp/consul/agent/grpc-middleware/testutil/testservice.(*SimplePanic).Something`)
+
 }
diff --git a/agent/grpc-internal/server_test.go b/agent/grpc-internal/server_test.go
index 45e1ad59f..56e18da1d 100644
--- a/agent/grpc-internal/server_test.go
+++ b/agent/grpc-internal/server_test.go
@@ -1,7 +1,6 @@
 package internal
 
 import (
-	"context"
 	"crypto/tls"
 	"fmt"
 	"io"
@@ -15,7 +14,7 @@ import (
 	"golang.org/x/sync/errgroup"
 	"google.golang.org/grpc"
 
-	"github.com/hashicorp/consul/agent/grpc-internal/internal/testservice"
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil/testservice"
 	"github.com/hashicorp/consul/agent/metadata"
 	"github.com/hashicorp/consul/agent/pool"
 	"github.com/hashicorp/consul/tlsutil"
@@ -42,20 +41,20 @@ func (s testServer) Metadata() *metadata.Server {
 
 func newSimpleTestServer(t *testing.T, name, dc string, tlsConf *tlsutil.Configurator) testServer {
 	return newTestServer(t, hclog.Default(), name, dc, tlsConf, func(server *grpc.Server) {
-		testservice.RegisterSimpleServer(server, &simple{name: name, dc: dc})
+		testservice.RegisterSimpleServer(server, &testservice.Simple{Name: name, DC: dc})
 	})
 }
 
 // newPanicTestServer sets up a simple server with handlers that panic.
 func newPanicTestServer(t *testing.T, logger hclog.Logger, name, dc string, tlsConf *tlsutil.Configurator) testServer {
 	return newTestServer(t, logger, name, dc, tlsConf, func(server *grpc.Server) {
-		testservice.RegisterSimpleServer(server, &simplePanic{name: name, dc: dc})
+		testservice.RegisterSimpleServer(server, &testservice.SimplePanic{Name: name, DC: dc})
 	})
 }
 
 func newTestServer(t *testing.T, logger hclog.Logger, name, dc string, tlsConf *tlsutil.Configurator, register func(server *grpc.Server)) testServer {
 	addr := &net.IPAddr{IP: net.ParseIP("127.0.0.1")}
-	handler := NewHandler(logger, addr, register)
+	handler := NewHandler(logger, addr, register, nil)
 
 	lis, err := net.Listen("tcp", "127.0.0.1:0")
 	require.NoError(t, err)
@@ -95,43 +94,6 @@ func newTestServer(t *testing.T, logger hclog.Logger, name, dc string, tlsConf *
 	}
 }
 
-type simple struct {
-	name string
-	dc   string
-}
-
-func (s *simple) Flow(_ *testservice.Req, flow testservice.Simple_FlowServer) error {
-	for flow.Context().Err() == nil {
-		resp := &testservice.Resp{ServerName: "one", Datacenter: s.dc}
-		if err := flow.Send(resp); err != nil {
-			return err
-		}
-		time.Sleep(time.Millisecond)
-	}
-	return nil
-}
-
-func (s *simple) Something(_ context.Context, _ *testservice.Req) (*testservice.Resp, error) {
-	return &testservice.Resp{ServerName: s.name, Datacenter: s.dc}, nil
-}
-
-type simplePanic struct {
-	name, dc string
-}
-
-func (s *simplePanic) Flow(_ *testservice.Req, flow testservice.Simple_FlowServer) error {
-	for flow.Context().Err() == nil {
-		time.Sleep(time.Millisecond)
-		panic("panic from Flow")
-	}
-	return nil
-}
-
-func (s *simplePanic) Something(_ context.Context, _ *testservice.Req) (*testservice.Resp, error) {
-	time.Sleep(time.Millisecond)
-	panic("panic from Something")
-}
-
 // fakeRPCListener mimics agent/consul.Server.listen to handle the RPCType byte.
 // In the future we should be able to refactor Server and extract this RPC
 // handling logic so that we don't need to use a fake.
diff --git a/agent/grpc-internal/services/subscribe/subscribe_test.go b/agent/grpc-internal/services/subscribe/subscribe_test.go
index 26a8e148c..c737b4d4a 100644
--- a/agent/grpc-internal/services/subscribe/subscribe_test.go
+++ b/agent/grpc-internal/services/subscribe/subscribe_test.go
@@ -370,10 +370,15 @@ var _ Backend = (*testBackend)(nil)
 func runTestServer(t *testing.T, server *Server) net.Addr {
 	addr := &net.IPAddr{IP: net.ParseIP("127.0.0.1")}
 	var grpcServer *gogrpc.Server
-	handler := grpc.NewHandler(hclog.New(nil), addr, func(srv *gogrpc.Server) {
-		grpcServer = srv
-		pbsubscribe.RegisterStateChangeSubscriptionServer(srv, server)
-	})
+	handler := grpc.NewHandler(
+		hclog.New(nil),
+		addr,
+		func(srv *gogrpc.Server) {
+			grpcServer = srv
+			pbsubscribe.RegisterStateChangeSubscriptionServer(srv, server)
+		},
+		nil,
+	)
 
 	lis, err := net.Listen("tcp", "127.0.0.1:0")
 	require.NoError(t, err)
diff --git a/agent/grpc-internal/stats_test.go b/agent/grpc-internal/stats_test.go
index a32ea5525..8ded41dd8 100644
--- a/agent/grpc-internal/stats_test.go
+++ b/agent/grpc-internal/stats_test.go
@@ -4,9 +4,7 @@ import (
 	"context"
 	"net"
 	"sort"
-	"sync"
 	"testing"
-	"time"
 
 	"github.com/armon/go-metrics"
 	"github.com/google/go-cmp/cmp"
@@ -16,20 +14,20 @@ import (
 
 	"github.com/hashicorp/go-hclog"
 
-	"github.com/hashicorp/consul/agent/grpc-internal/internal/testservice"
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil"
+	"github.com/hashicorp/consul/agent/grpc-middleware/testutil/testservice"
 	"github.com/hashicorp/consul/proto/prototest"
 )
 
 func noopRegister(*grpc.Server) {}
 
 func TestHandler_EmitsStats(t *testing.T) {
-	sink, reset := patchGlobalMetrics(t)
+	sink, metricsObj := testutil.NewFakeSink(t)
 
 	addr := &net.IPAddr{IP: net.ParseIP("127.0.0.1")}
-	handler := NewHandler(hclog.Default(), addr, noopRegister)
-	reset()
+	handler := NewHandler(hclog.Default(), addr, noopRegister, metricsObj)
 
-	testservice.RegisterSimpleServer(handler.srv, &simple{})
+	testservice.RegisterSimpleServer(handler.srv, &testservice.Simple{})
 
 	lis, err := net.Listen("tcp", "127.0.0.1:0")
 	require.NoError(t, err)
@@ -71,80 +69,35 @@ func TestHandler_EmitsStats(t *testing.T) {
 	// Occasionally the active_stream=0 metric may be emitted before the
 	// active_conns=0 metric. The order of those metrics is not really important
 	// so we sort the calls to match the expected.
-	sort.Slice(sink.gaugeCalls, func(i, j int) bool {
+	sort.Slice(sink.GaugeCalls, func(i, j int) bool {
 		if i < 2 || j < 2 {
 			return i < j
 		}
-		if len(sink.gaugeCalls[i].key) < 4 || len(sink.gaugeCalls[j].key) < 4 {
+		if len(sink.GaugeCalls[i].Key) < 4 || len(sink.GaugeCalls[j].Key) < 4 {
 			return i < j
 		}
-		return sink.gaugeCalls[i].key[3] < sink.gaugeCalls[j].key[3]
+		return sink.GaugeCalls[i].Key[3] < sink.GaugeCalls[j].Key[3]
 	})
 
-	cmpMetricCalls := cmp.AllowUnexported(metricCall{})
-	expectedGauge := []metricCall{
-		{key: []string{"testing", "grpc", "server", "connections"}, val: 1},
-		{key: []string{"testing", "grpc", "server", "streams"}, val: 1},
-		{key: []string{"testing", "grpc", "server", "connections"}, val: 0},
-		{key: []string{"testing", "grpc", "server", "streams"}, val: 0},
+	cmpMetricCalls := cmp.AllowUnexported(testutil.MetricCall{})
+	expLabels := []metrics.Label{{
+		Name:  "server_type",
+		Value: "internal",
+	}}
+	expectedGauge := []testutil.MetricCall{
+		{Key: []string{"testing", "grpc", "server", "connections"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "streams"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "connections"}, Val: 0, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "streams"}, Val: 0, Labels: expLabels},
 	}
-	prototest.AssertDeepEqual(t, expectedGauge, sink.gaugeCalls, cmpMetricCalls)
+	prototest.AssertDeepEqual(t, expectedGauge, sink.GaugeCalls, cmpMetricCalls)
 
-	expectedCounter := []metricCall{
-		{key: []string{"testing", "grpc", "server", "connection", "count"}, val: 1},
-		{key: []string{"testing", "grpc", "server", "request", "count"}, val: 1},
-		{key: []string{"testing", "grpc", "server", "stream", "count"}, val: 1},
+	expectedCounter := []testutil.MetricCall{
+		{Key: []string{"testing", "grpc", "server", "connection", "count"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "request", "count"}, Val: 1, Labels: expLabels},
+		{Key: []string{"testing", "grpc", "server", "stream", "count"}, Val: 1, Labels: expLabels},
 	}
-	prototest.AssertDeepEqual(t, expectedCounter, sink.incrCounterCalls, cmpMetricCalls)
-}
-
-func patchGlobalMetrics(t *testing.T) (*fakeMetricsSink, func()) {
-	t.Helper()
-
-	sink := &fakeMetricsSink{}
-	cfg := &metrics.Config{
-		ServiceName:      "testing",
-		TimerGranularity: time.Millisecond, // Timers are in milliseconds
-		ProfileInterval:  time.Second,      // Poll runtime every second
-		FilterDefault:    true,
-	}
-	var err error
-	defaultMetrics = func() *metrics.Metrics {
-		m, _ := metrics.New(cfg, sink)
-		return m
-	}
-	require.NoError(t, err)
-	reset := func() {
-		t.Helper()
-		defaultMetrics = metrics.Default
-		require.NoError(t, err, "failed to reset global metrics")
-	}
-	return sink, reset
-}
-
-type fakeMetricsSink struct {
-	lock sync.Mutex
-	metrics.BlackholeSink
-	gaugeCalls       []metricCall
-	incrCounterCalls []metricCall
-}
-
-func (f *fakeMetricsSink) SetGaugeWithLabels(key []string, val float32, labels []metrics.Label) {
-	f.lock.Lock()
-	f.gaugeCalls = append(f.gaugeCalls, metricCall{key: key, val: val, labels: labels})
-	f.lock.Unlock()
-}
-
-func (f *fakeMetricsSink) IncrCounterWithLabels(key []string, val float32, labels []metrics.Label) {
-	f.lock.Lock()
-	f.incrCounterCalls = append(f.incrCounterCalls, metricCall{key: key, val: val, labels: labels})
-	f.lock.Unlock()
-}
-
-type metricCall struct {
-	key    []string
-	val    float32
-	labels []metrics.Label
+	prototest.AssertDeepEqual(t, expectedCounter, sink.IncrCounterCalls, cmpMetricCalls)
 }
 
 func logError(t *testing.T, f func() error) func() {
diff --git a/agent/grpc-internal/stats.go b/agent/grpc-middleware/stats.go
similarity index 79%
rename from agent/grpc-internal/stats.go
rename to agent/grpc-middleware/stats.go
index ab5226cee..3a1b3f23e 100644
--- a/agent/grpc-internal/stats.go
+++ b/agent/grpc-middleware/stats.go
@@ -1,4 +1,4 @@
-package internal
+package middleware
 
 import (
 	"context"
@@ -47,8 +47,6 @@ var StatsCounters = []prometheus.CounterDefinition{
 	},
 }
 
-var defaultMetrics = metrics.Default
-
 // statsHandler is a grpc/stats.StatsHandler which emits connection and
 // request metrics to go-metrics.
 type statsHandler struct {
@@ -57,10 +55,11 @@ type statsHandler struct {
 	// the struct. See https://golang.org/pkg/sync/atomic/#pkg-note-BUG.
 	activeConns uint64
 	metrics     *metrics.Metrics
+	labels      []metrics.Label
 }
 
-func newStatsHandler(m *metrics.Metrics) *statsHandler {
-	return &statsHandler{metrics: m}
+func NewStatsHandler(m *metrics.Metrics, labels []metrics.Label) *statsHandler {
+	return &statsHandler{metrics: m, labels: labels}
 }
 
 // TagRPC implements grpcStats.StatsHandler
@@ -77,7 +76,7 @@ func (c *statsHandler) HandleRPC(_ context.Context, s stats.RPCStats) {
 	}
 	switch s.(type) {
 	case *stats.InHeader:
-		c.metrics.IncrCounter([]string{"grpc", label, "request", "count"}, 1)
+		c.metrics.IncrCounterWithLabels([]string{"grpc", label, "request", "count"}, 1, c.labels)
 	}
 }
 
@@ -97,12 +96,12 @@ func (c *statsHandler) HandleConn(_ context.Context, s stats.ConnStats) {
 	switch s.(type) {
 	case *stats.ConnBegin:
 		count = atomic.AddUint64(&c.activeConns, 1)
-		c.metrics.IncrCounter([]string{"grpc", label, "connection", "count"}, 1)
+		c.metrics.IncrCounterWithLabels([]string{"grpc", label, "connection", "count"}, 1, c.labels)
 	case *stats.ConnEnd:
 		// Decrement!
 		count = atomic.AddUint64(&c.activeConns, ^uint64(0))
 	}
-	c.metrics.SetGauge([]string{"grpc", label, "connections"}, float32(count))
+	c.metrics.SetGaugeWithLabels([]string{"grpc", label, "connections"}, float32(count), c.labels)
 }
 
 type activeStreamCounter struct {
@@ -111,6 +110,11 @@ type activeStreamCounter struct {
 	// the struct. See https://golang.org/pkg/sync/atomic/#pkg-note-BUG.
 	count   uint64
 	metrics *metrics.Metrics
+	labels  []metrics.Label
+}
+
+func NewActiveStreamCounter(m *metrics.Metrics, labels []metrics.Label) *activeStreamCounter {
+	return &activeStreamCounter{metrics: m, labels: labels}
 }
 
 // GRPCCountingStreamInterceptor is a grpc.ServerStreamInterceptor that emits a
@@ -122,11 +126,11 @@ func (i *activeStreamCounter) Intercept(
 	handler grpc.StreamHandler,
 ) error {
 	count := atomic.AddUint64(&i.count, 1)
-	i.metrics.SetGauge([]string{"grpc", "server", "streams"}, float32(count))
-	i.metrics.IncrCounter([]string{"grpc", "server", "stream", "count"}, 1)
+	i.metrics.SetGaugeWithLabels([]string{"grpc", "server", "streams"}, float32(count), i.labels)
+	i.metrics.IncrCounterWithLabels([]string{"grpc", "server", "stream", "count"}, 1, i.labels)
 	defer func() {
 		count := atomic.AddUint64(&i.count, ^uint64(0))
-		i.metrics.SetGauge([]string{"grpc", "server", "streams"}, float32(count))
+		i.metrics.SetGaugeWithLabels([]string{"grpc", "server", "streams"}, float32(count), i.labels)
 	}()
 
 	return handler(srv, ss)
diff --git a/agent/grpc-middleware/testutil/fake_sink.go b/agent/grpc-middleware/testutil/fake_sink.go
new file mode 100644
index 000000000..7439d78a2
--- /dev/null
+++ b/agent/grpc-middleware/testutil/fake_sink.go
@@ -0,0 +1,50 @@
+package testutil
+
+import (
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/armon/go-metrics"
+	"github.com/stretchr/testify/require"
+)
+
+func NewFakeSink(t *testing.T) (*FakeMetricsSink, *metrics.Metrics) {
+	t.Helper()
+
+	sink := &FakeMetricsSink{}
+	cfg := &metrics.Config{
+		ServiceName:      "testing",
+		TimerGranularity: time.Millisecond, // Timers are in milliseconds
+		ProfileInterval:  time.Second,      // Poll runtime every second
+		FilterDefault:    true,
+	}
+	m, err := metrics.New(cfg, sink)
+	require.NoError(t, err)
+	return sink, m
+}
+
+type FakeMetricsSink struct {
+	lock sync.Mutex
+	metrics.BlackholeSink
+	GaugeCalls       []MetricCall
+	IncrCounterCalls []MetricCall
+}
+
+func (f *FakeMetricsSink) SetGaugeWithLabels(key []string, val float32, labels []metrics.Label) {
+	f.lock.Lock()
+	f.GaugeCalls = append(f.GaugeCalls, MetricCall{Key: key, Val: val, Labels: labels})
+	f.lock.Unlock()
+}
+
+func (f *FakeMetricsSink) IncrCounterWithLabels(key []string, val float32, labels []metrics.Label) {
+	f.lock.Lock()
+	f.IncrCounterCalls = append(f.IncrCounterCalls, MetricCall{Key: key, Val: val, Labels: labels})
+	f.lock.Unlock()
+}
+
+type MetricCall struct {
+	Key    []string
+	Val    float32
+	Labels []metrics.Label
+}
diff --git a/agent/grpc-middleware/testutil/testservice/fake_service.go b/agent/grpc-middleware/testutil/testservice/fake_service.go
new file mode 100644
index 000000000..f9999cc71
--- /dev/null
+++ b/agent/grpc-middleware/testutil/testservice/fake_service.go
@@ -0,0 +1,43 @@
+package testservice
+
+import (
+	"context"
+	"time"
+)
+
+type Simple struct {
+	Name string
+	DC   string
+}
+
+func (s *Simple) Flow(_ *Req, flow Simple_FlowServer) error {
+	for flow.Context().Err() == nil {
+		resp := &Resp{ServerName: "one", Datacenter: s.DC}
+		if err := flow.Send(resp); err != nil {
+			return err
+		}
+		time.Sleep(time.Millisecond)
+	}
+	return nil
+}
+
+func (s *Simple) Something(_ context.Context, _ *Req) (*Resp, error) {
+	return &Resp{ServerName: s.Name, Datacenter: s.DC}, nil
+}
+
+type SimplePanic struct {
+	Name, DC string
+}
+
+func (s *SimplePanic) Flow(_ *Req, flow Simple_FlowServer) error {
+	for flow.Context().Err() == nil {
+		time.Sleep(time.Millisecond)
+		panic("panic from Flow")
+	}
+	return nil
+}
+
+func (s *SimplePanic) Something(_ context.Context, _ *Req) (*Resp, error) {
+	time.Sleep(time.Millisecond)
+	panic("panic from Something")
+}
diff --git a/agent/grpc-internal/internal/testservice/simple.pb.binary.go b/agent/grpc-middleware/testutil/testservice/simple.pb.binary.go
similarity index 90%
rename from agent/grpc-internal/internal/testservice/simple.pb.binary.go
rename to agent/grpc-middleware/testutil/testservice/simple.pb.binary.go
index fd2d7e13f..da258818d 100644
--- a/agent/grpc-internal/internal/testservice/simple.pb.binary.go
+++ b/agent/grpc-middleware/testutil/testservice/simple.pb.binary.go
@@ -1,5 +1,5 @@
 // Code generated by protoc-gen-go-binary. DO NOT EDIT.
-// source: agent/grpc-internal/internal/testservice/simple.proto
+// source: agent/grpc-middleware/testutil/testservice/simple.pb.binary.go
 
 package testservice
 
diff --git a/agent/grpc-internal/internal/testservice/simple.pb.go b/agent/grpc-middleware/testutil/testservice/simple.pb.go
similarity index 99%
rename from agent/grpc-internal/internal/testservice/simple.pb.go
rename to agent/grpc-middleware/testutil/testservice/simple.pb.go
index dfca35fa0..25aa074f7 100644
--- a/agent/grpc-internal/internal/testservice/simple.pb.go
+++ b/agent/grpc-middleware/testutil/testservice/simple.pb.go
@@ -2,7 +2,7 @@
 // versions:
 // 	protoc-gen-go v1.23.0
 // 	protoc        v3.15.8
-// source: agent/grpc-internal/internal/testservice/simple.proto
+// source: agent/grpc-middleware/testutil/testservice/simple.proto
 
 package testservice
 
diff --git a/agent/grpc-internal/internal/testservice/simple.proto b/agent/grpc-middleware/testutil/testservice/simple.proto
similarity index 100%
rename from agent/grpc-internal/internal/testservice/simple.proto
rename to agent/grpc-middleware/testutil/testservice/simple.proto
diff --git a/agent/rpc/peering/service_test.go b/agent/rpc/peering/service_test.go
index ae822c24a..7f21b9578 100644
--- a/agent/rpc/peering/service_test.go
+++ b/agent/rpc/peering/service_test.go
@@ -1414,7 +1414,7 @@ func newTestServer(t *testing.T, cb func(conf *consul.Config)) testingServer {
 	conf.ACLResolverSettings.EnterpriseMeta = *conf.AgentEnterpriseMeta()
 
 	deps := newDefaultDeps(t, conf)
-	externalGRPCServer := external.NewServer(deps.Logger)
+	externalGRPCServer := external.NewServer(deps.Logger, nil)
 
 	server, err := consul.NewServer(conf, deps, externalGRPCServer)
 	require.NoError(t, err)
diff --git a/agent/setup.go b/agent/setup.go
index 4fdeab213..02dc03426 100644
--- a/agent/setup.go
+++ b/agent/setup.go
@@ -21,8 +21,9 @@ import (
 	"github.com/hashicorp/consul/agent/consul/usagemetrics"
 	"github.com/hashicorp/consul/agent/consul/xdscapacity"
 	"github.com/hashicorp/consul/agent/grpc-external/limiter"
-	grpc "github.com/hashicorp/consul/agent/grpc-internal"
+	grpcInt "github.com/hashicorp/consul/agent/grpc-internal"
 	"github.com/hashicorp/consul/agent/grpc-internal/resolver"
+	grpcWare "github.com/hashicorp/consul/agent/grpc-middleware"
 	"github.com/hashicorp/consul/agent/local"
 	"github.com/hashicorp/consul/agent/pool"
 	"github.com/hashicorp/consul/agent/router"
@@ -112,11 +113,11 @@ func NewBaseDeps(configLoader ConfigLoader, logOut io.Writer) (BaseDeps, error)
 		Authority: cfg.Datacenter + "." + string(cfg.NodeID),
 	})
 	resolver.Register(builder)
-	d.GRPCConnPool = grpc.NewClientConnPool(grpc.ClientConnPoolConfig{
+	d.GRPCConnPool = grpcInt.NewClientConnPool(grpcInt.ClientConnPoolConfig{
 		Servers:               builder,
 		SrcAddr:               d.ConnPool.SrcAddr,
-		TLSWrapper:            grpc.TLSWrapper(d.TLSConfigurator.OutgoingRPCWrapper()),
-		ALPNWrapper:           grpc.ALPNWrapper(d.TLSConfigurator.OutgoingALPNRPCWrapper()),
+		TLSWrapper:            grpcInt.TLSWrapper(d.TLSConfigurator.OutgoingRPCWrapper()),
+		ALPNWrapper:           grpcInt.ALPNWrapper(d.TLSConfigurator.OutgoingALPNRPCWrapper()),
 		UseTLSForDC:           d.TLSConfigurator.UseTLS,
 		DialingFromServer:     cfg.ServerMode,
 		DialingFromDatacenter: cfg.Datacenter,
@@ -201,7 +202,8 @@ func newConnPool(config *config.RuntimeConfig, logger hclog.Logger, tls *tlsutil
 }
 
 // getPrometheusDefs reaches into every slice of prometheus defs we've defined in each part of the agent, and appends
-//  all of our slices into one nice slice of definitions per metric type for the Consul agent to pass to go-metrics.
+//
+//	all of our slices into one nice slice of definitions per metric type for the Consul agent to pass to go-metrics.
 func getPrometheusDefs(cfg lib.TelemetryConfig, isServer bool) ([]prometheus.GaugeDefinition, []prometheus.CounterDefinition, []prometheus.SummaryDefinition) {
 	// TODO: "raft..." metrics come from the raft lib and we should migrate these to a telemetry
 	//  package within. In the mean time, we're going to define a few here because they're key to monitoring Consul.
@@ -228,7 +230,7 @@ func getPrometheusDefs(cfg lib.TelemetryConfig, isServer bool) ([]prometheus.Gau
 		cache.Gauges,
 		consul.RPCGauges,
 		consul.SessionGauges,
-		grpc.StatsGauges,
+		grpcWare.StatsGauges,
 		xds.StatsGauges,
 		usagemetrics.Gauges,
 		consul.ReplicationGauges,
@@ -286,7 +288,7 @@ func getPrometheusDefs(cfg lib.TelemetryConfig, isServer bool) ([]prometheus.Gau
 		consul.CatalogCounters,
 		consul.ClientCounters,
 		consul.RPCCounters,
-		grpc.StatsCounters,
+		grpcWare.StatsCounters,
 		local.StateCounters,
 		xds.StatsCounters,
 		raftCounters,