[baseserver] Add prometheus metrics

Author: easyCZ

components/common-go/baseserver/options.go

@@ -7,6 +7,7 @@ package baseserver
 import (
 	"fmt"
 	"github.com/gitpod-io/gitpod/common-go/log"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
 	"time"
 )
@@ -23,6 +24,9 @@ type config struct {
 
 	// closeTimeout is the amount we allow for the server to shut down cleanly
 	closeTimeout time.Duration
+
+	// metricsRegistry configures the metrics registry to use for exporting metrics. When not set, the default prometheus registry is used.
+	metricsRegistry *prometheus.Registry
 }
 
 func defaultConfig() *config {
@@ -46,7 +50,7 @@ func WithHostname(hostname string) Option {
 
 func WithHTTPPort(port int) Option {
 	return func(cfg *config) error {
-		if port <= 0 {
+		if port < 0 {
 			return fmt.Errorf("http port must be greater than 0, got: %d", port)
 		}
 
@@ -84,6 +88,17 @@ func WithCloseTimeout(d time.Duration) Option {
 	}
 }
 
+func WithMetricsRegistry(r *prometheus.Registry) Option {
+	return func(cfg *config) error {
+		if r == nil {
+			return fmt.Errorf("nil prometheus registry received")
+		}
+
+		cfg.metricsRegistry = r
+		return nil
+	}
+}
+
 func evaluateOptions(cfg *config, opts ...Option) (*config, error) {
 	for _, opt := range opts {
 		if err := opt(cfg); err != nil {

components/common-go/baseserver/options_test.go

@@ -6,6 +6,7 @@ package baseserver
 
 import (
 	"github.com/gitpod-io/gitpod/common-go/log"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/require"
 	"testing"
 	"time"
@@ -17,23 +18,26 @@ func TestOptions(t *testing.T) {
 	grpcPort := 8081
 	timeout := 10 * time.Second
 	hostname := "another_hostname"
+	registry := prometheus.NewRegistry()
 
 	var opts = []Option{
 		WithHostname(hostname),
 		WithHTTPPort(httpPort),
 		WithGRPCPort(grpcPort),
 		WithLogger(logger),
 		WithCloseTimeout(timeout),
+		WithMetricsRegistry(registry),
 	}
 	cfg, err := evaluateOptions(defaultConfig(), opts...)
 	require.NoError(t, err)
 
 	require.Equal(t, &config{
-		logger:       logger,
-		hostname:     hostname,
-		grpcPort:     grpcPort,
-		httpPort:     httpPort,
-		closeTimeout: timeout,
+		logger:          logger,
+		hostname:        hostname,
+		grpcPort:        grpcPort,
+		httpPort:        httpPort,
+		closeTimeout:    timeout,
+		metricsRegistry: registry,
 	}, cfg)
 }
 

components/common-go/baseserver/server.go

@@ -7,6 +7,7 @@ package baseserver
 import (
 	"context"
 	"fmt"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc"
 	"net"
@@ -201,6 +202,15 @@ func (s *Server) newHTTPMux() *http.ServeMux {
 		_, _ = w.Write([]byte(`ready`))
 	})
 
+	// Metrics endpoint
+	metricsHandler := promhttp.Handler()
+	if s.cfg.metricsRegistry != nil {
+		metricsHandler = promhttp.InstrumentMetricHandler(
+			s.cfg.metricsRegistry, promhttp.HandlerFor(s.cfg.metricsRegistry, promhttp.HandlerOpts{}),
+		)
+	}
+	mux.Handle("/metrics", metricsHandler)
+
 	return mux
 }
 

components/common-go/baseserver/server_test.go

@@ -7,6 +7,7 @@ package baseserver_test
 import (
 	"fmt"
 	"github.com/gitpod-io/gitpod/common-go/baseserver"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/require"
 	"net/http"
 	"testing"
@@ -40,3 +41,36 @@ func TestServer_ServesReady(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, http.StatusOK, resp.StatusCode)
 }
+
+func TestServer_ServesMetricsEndpointWithDefaultConfig(t *testing.T) {
+	srv := baseserver.NewForTests(t)
+
+	go func(t *testing.T) {
+		require.NoError(t, srv.ListenAndServe())
+	}(t)
+
+	baseserver.WaitForServerToBeReachable(t, srv, 3*time.Second)
+
+	readyUR := fmt.Sprintf("%s/metrics", srv.HTTPAddress())
+	resp, err := http.Get(readyUR)
+	require.NoError(t, err)
+	require.Equal(t, http.StatusOK, resp.StatusCode)
+}
+
+func TestServer_ServesMetricsEndpointWithCustomMetricsConfig(t *testing.T) {
+	registry := prometheus.NewRegistry()
+	srv := baseserver.NewForTests(t,
+		baseserver.WithMetricsRegistry(registry),
+	)
+
+	go func(t *testing.T) {
+		require.NoError(t, srv.ListenAndServe())
+	}(t)
+
+	baseserver.WaitForServerToBeReachable(t, srv, 3*time.Second)
+
+	readyUR := fmt.Sprintf("%s/metrics", srv.HTTPAddress())
+	resp, err := http.Get(readyUR)
+	require.NoError(t, err)
+	require.Equal(t, http.StatusOK, resp.StatusCode)
+}

components/public-api-server/go.mod

@@ -5,9 +5,16 @@ go 1.17
 require github.com/gitpod-io/gitpod/common-go v0.0.0-00010101000000-000000000000
 
 require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_golang v1.12.1 // indirect
+	github.com/prometheus/client_model v0.2.0 // indirect
+	github.com/prometheus/common v0.32.1 // indirect
+	github.com/prometheus/procfs v0.7.3 // indirect
 	github.com/sirupsen/logrus v1.8.1 // indirect
 	github.com/stretchr/testify v1.7.0 // indirect
 	golang.org/x/net v0.0.0-20211209124913-491a49abca63 // indirect