Add metrics server test

lib/service/service.go

@@ -665,7 +665,7 @@ type TeleportProcess struct {
 	// conflicts.
 	//
 	// Both the metricsRegistry and the default global registry are gathered by
-	// Telpeort's metric service.
+	// Telepeort's metric service.
 	metricsRegistry *prometheus.Registry
 }
 

lib/service/service_test.go

@@ -23,9 +23,11 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -39,6 +41,8 @@ import (
 	"github.com/google/uuid"
 	"github.com/gravitational/trace"
 	"github.com/jonboulle/clockwork"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/sync/errgroup"
 	"google.golang.org/grpc"
@@ -1887,7 +1891,7 @@ func TestAgentRolloutController(t *testing.T) {
 	dataDir := makeTempDir(t)
 
 	cfg := servicecfg.MakeDefaultConfig()
-	// We use a real clock because too many sevrices are using the clock and it's not possible to accurately wait for
+	// We use a real clock because too many services are using the clock and it's not possible to accurately wait for
 	// each one of them to reach the point where they wait for the clock to advance. If we add a WaitUntil(X waiters)
 	// check, this will break the next time we add a new waiter.
 	cfg.Clock = clockwork.NewRealClock()
@@ -1906,7 +1910,7 @@ func TestAgentRolloutController(t *testing.T) {
 	process, err := NewTeleport(cfg)
 	require.NoError(t, err)
 
-	// Test setup: start the Teleport auth and wait for it to beocme ready
+	// Test setup: start the Teleport auth and wait for it to become ready
 	require.NoError(t, process.Start())
 
 	// Test setup: wait for every service to start
@@ -1949,6 +1953,84 @@ func TestAgentRolloutController(t *testing.T) {
 	}, 5*time.Second, 10*time.Millisecond)
 }
 
+func TestMetricsService(t *testing.T) {
+	t.Parallel()
+	// Test setup: create a listener for the metrics server, get its file descriptor.
+
+	// Note: this code is copied from integrations/helpers/NewListenerOn() to avoid including helpers in a production
+	// build and avoid a cyclic dependency.
+	metricsListener, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		assert.NoError(t, metricsListener.Close())
+	})
+	require.IsType(t, &net.TCPListener{}, metricsListener)
+	metricsListenerFile, err := metricsListener.(*net.TCPListener).File()
+	require.NoError(t, err)
+
+	// Test setup: create a new teleport process
+	dataDir := makeTempDir(t)
+	cfg := servicecfg.MakeDefaultConfig()
+	cfg.DataDir = dataDir
+	cfg.SetAuthServerAddress(utils.NetAddr{AddrNetwork: "tcp", Addr: "127.0.0.1:0"})
+	cfg.Auth.Enabled = true
+	cfg.Proxy.Enabled = false
+	cfg.SSH.Enabled = false
+	cfg.DebugService.Enabled = false
+	cfg.Auth.StorageConfig.Params["path"] = dataDir
+	cfg.Auth.ListenAddr = utils.NetAddr{AddrNetwork: "tcp", Addr: "127.0.0.1:0"}
+	cfg.Metrics.Enabled = true
+
+	// Configure the metrics server to use the listener we previously created.
+	cfg.Metrics.ListenAddr = &utils.NetAddr{AddrNetwork: "tcp", Addr: metricsListener.Addr().String()}
+	cfg.FileDescriptors = []*servicecfg.FileDescriptor{
+		{Type: string(ListenerMetrics), Address: metricsListener.Addr().String(), File: metricsListenerFile},
+	}
+
+	// Create and start the Teleport service.
+	process, err := NewTeleport(cfg)
+	require.NoError(t, err)
+	require.NoError(t, process.Start())
+	t.Cleanup(func() {
+		assert.NoError(t, process.Close())
+		assert.NoError(t, process.Wait())
+	})
+
+	// Test setup: create our test metrics.
+	nonce := strings.ReplaceAll(uuid.New().String(), "-", "")
+	localMetric := prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "test",
+		Name:      "local_metric_" + nonce,
+	})
+	globalMetric := prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "test",
+		Name:      "global_metric_" + nonce,
+	})
+	require.NoError(t, process.metricsRegistry.Register(localMetric))
+	require.NoError(t, prometheus.Register(globalMetric))
+
+	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
+	t.Cleanup(cancel)
+	_, err = process.WaitForEvent(ctx, MetricsReady)
+	require.NoError(t, err)
+
+	// Test execution: get metrics and check the tests metrics are here.
+	metricsURL, err := url.Parse("http://" + metricsListener.Addr().String())
+	require.NoError(t, err)
+	metricsURL.Path = "/metrics"
+	resp, err := http.Get(metricsURL.String())
+	require.NoError(t, err)
+	require.Equal(t, http.StatusOK, resp.StatusCode)
+
+	body, err := io.ReadAll(resp.Body)
+	require.NoError(t, err)
+	require.NoError(t, resp.Body.Close())
+
+	// Test validation: check that the metrics server served both the local and global registry.
+	require.Contains(t, string(body), "local_metric_"+nonce)
+	require.Contains(t, string(body), "global_metric_"+nonce)
+}
+
 // makeTempDir makes a temp dir with a shorter name than t.TempDir() in order to
 // avoid https://github.com/golang/go/issues/62614.
 func makeTempDir(t *testing.T) string {