TUN-9511: Add metrics for virtual DNS origin

Closes TUN-9511

cmd/cloudflared/tunnel/configuration.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/rs/zerolog"
 	"github.com/urfave/cli/v2"
 	"github.com/urfave/cli/v2/altsrc"
@@ -229,14 +230,15 @@ func prepareTunnelConfig(
 	}, log)
 
 	// Setup DNS Resolver Service
+	originMetrics := origins.NewMetrics(prometheus.DefaultRegisterer)
 	dnsResolverAddrs := c.StringSlice(flags.VirtualDNSServiceResolverAddresses)
-	dnsService := origins.NewDNSResolverService(origins.NewDNSDialer(), log)
+	dnsService := origins.NewDNSResolverService(origins.NewDNSDialer(), log, originMetrics)
 	if len(dnsResolverAddrs) > 0 {
 		addrs, err := parseResolverAddrPorts(dnsResolverAddrs)
 		if err != nil {
 			return nil, nil, fmt.Errorf("invalid %s provided: %w", flags.VirtualDNSServiceResolverAddresses, err)
 		}
-		dnsService = origins.NewStaticDNSResolverService(addrs, origins.NewDNSDialer(), log)
+		dnsService = origins.NewStaticDNSResolverService(addrs, origins.NewDNSDialer(), log, originMetrics)
 	}
 	originDialerService.AddReservedService(dnsService, []netip.AddrPort{origins.VirtualDNSServiceAddr})
 

ingress/origins/dns.go

@@ -51,31 +51,35 @@ type DNSResolverService struct {
 	dialer     ingress.OriginDialer
 	resolver   peekResolver
 	logger     *zerolog.Logger
+	metrics    Metrics
 }
 
-func NewDNSResolverService(dialer ingress.OriginDialer, logger *zerolog.Logger) *DNSResolverService {
+func NewDNSResolverService(dialer ingress.OriginDialer, logger *zerolog.Logger, metrics Metrics) *DNSResolverService {
 	return &DNSResolverService{
 		addresses: []netip.AddrPort{defaultResolverAddr},
 		dialer:    dialer,
 		resolver:  &resolver{dialFunc: net.Dial},
 		logger:    logger,
+		metrics:   metrics,
 	}
 }
 
-func NewStaticDNSResolverService(resolverAddrs []netip.AddrPort, dialer ingress.OriginDialer, logger *zerolog.Logger) *DNSResolverService {
+func NewStaticDNSResolverService(resolverAddrs []netip.AddrPort, dialer ingress.OriginDialer, logger *zerolog.Logger, metrics Metrics) *DNSResolverService {
-	s := NewDNSResolverService(dialer, logger)
+	s := NewDNSResolverService(dialer, logger, metrics)
 	s.addresses = resolverAddrs
 	s.static = true
 	return s
 }
 
 func (s *DNSResolverService) DialTCP(ctx context.Context, _ netip.AddrPort) (net.Conn, error) {
+	s.metrics.IncrementDNSTCPRequests()
 	dest := s.getAddress()
 	// The dialer ignores the provided address because the request will instead go to the local DNS resolver.
 	return s.dialer.DialTCP(ctx, dest)
 }
 
 func (s *DNSResolverService) DialUDP(_ netip.AddrPort) (net.Conn, error) {
+	s.metrics.IncrementDNSUDPRequests()
 	dest := s.getAddress()
 	// The dialer ignores the provided address because the request will instead go to the local DNS resolver.
 	return s.dialer.DialUDP(dest)

ingress/origins/dns_test.go

@@ -14,7 +14,7 @@ import (
 
 func TestDNSResolver_DefaultResolver(t *testing.T) {
 	log := zerolog.Nop()
-	service := NewDNSResolverService(NewDNSDialer(), &log)
+	service := NewDNSResolverService(NewDNSDialer(), &log, &noopMetrics{})
 	mockResolver := &mockPeekResolver{
 		address: "127.0.0.2:53",
 	}
@@ -25,7 +25,7 @@ func TestDNSResolver_DefaultResolver(t *testing.T) {
 func TestStaticDNSResolver_DefaultResolver(t *testing.T) {
 	log := zerolog.Nop()
 	addresses := []netip.AddrPort{netip.MustParseAddrPort("1.1.1.1:53"), netip.MustParseAddrPort("1.0.0.1:53")}
-	service := NewStaticDNSResolverService(addresses, NewDNSDialer(), &log)
+	service := NewStaticDNSResolverService(addresses, NewDNSDialer(), &log, &noopMetrics{})
 	mockResolver := &mockPeekResolver{
 		address: "127.0.0.2:53",
 	}
@@ -35,7 +35,7 @@ func TestStaticDNSResolver_DefaultResolver(t *testing.T) {
 
 func TestDNSResolver_UpdateResolverAddress(t *testing.T) {
 	log := zerolog.Nop()
-	service := NewDNSResolverService(NewDNSDialer(), &log)
+	service := NewDNSResolverService(NewDNSDialer(), &log, &noopMetrics{})
 
 	mockResolver := &mockPeekResolver{}
 	service.resolver = mockResolver
@@ -64,7 +64,7 @@ func TestDNSResolver_UpdateResolverAddress(t *testing.T) {
 func TestStaticDNSResolver_RefreshLoopExits(t *testing.T) {
 	log := zerolog.Nop()
 	addresses := []netip.AddrPort{netip.MustParseAddrPort("1.1.1.1:53"), netip.MustParseAddrPort("1.0.0.1:53")}
-	service := NewStaticDNSResolverService(addresses, NewDNSDialer(), &log)
+	service := NewStaticDNSResolverService(addresses, NewDNSDialer(), &log, &noopMetrics{})
 
 	mockResolver := &mockPeekResolver{
 		address: "127.0.0.2:53",
@@ -85,7 +85,7 @@ func TestStaticDNSResolver_RefreshLoopExits(t *testing.T) {
 
 func TestDNSResolver_UpdateResolverAddressInvalid(t *testing.T) {
 	log := zerolog.Nop()
-	service := NewDNSResolverService(NewDNSDialer(), &log)
+	service := NewDNSResolverService(NewDNSDialer(), &log, &noopMetrics{})
 	mockResolver := &mockPeekResolver{}
 	service.resolver = mockResolver
 
@@ -109,7 +109,7 @@ func TestDNSResolver_UpdateResolverAddressInvalid(t *testing.T) {
 
 func TestDNSResolver_UpdateResolverErrorIgnored(t *testing.T) {
 	log := zerolog.Nop()
-	service := NewDNSResolverService(NewDNSDialer(), &log)
+	service := NewDNSResolverService(NewDNSDialer(), &log, &noopMetrics{})
 	resolverErr := errors.New("test resolver error")
 	mockResolver := &mockPeekResolver{err: resolverErr}
 	service.resolver = mockResolver
@@ -126,7 +126,7 @@ func TestDNSResolver_UpdateResolverErrorIgnored(t *testing.T) {
 func TestDNSResolver_DialUDPUsesResolvedAddress(t *testing.T) {
 	log := zerolog.Nop()
 	mockDialer := &mockDialer{expected: defaultResolverAddr}
-	service := NewDNSResolverService(mockDialer, &log)
+	service := NewDNSResolverService(mockDialer, &log, &noopMetrics{})
 	mockResolver := &mockPeekResolver{}
 	service.resolver = mockResolver
 
@@ -140,7 +140,7 @@ func TestDNSResolver_DialUDPUsesResolvedAddress(t *testing.T) {
 func TestDNSResolver_DialTCPUsesResolvedAddress(t *testing.T) {
 	log := zerolog.Nop()
 	mockDialer := &mockDialer{expected: defaultResolverAddr}
-	service := NewDNSResolverService(mockDialer, &log)
+	service := NewDNSResolverService(mockDialer, &log, &noopMetrics{})
 	mockResolver := &mockPeekResolver{}
 	service.resolver = mockResolver
 

ingress/origins/metrics.go

@@ -0,0 +1,40 @@
+package origins
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	namespace = "cloudflared"
+	subsystem = "virtual_origins"
+)
+
+type Metrics interface {
+	IncrementDNSUDPRequests()
+	IncrementDNSTCPRequests()
+}
+
+type metrics struct {
+	dnsResolverRequests *prometheus.CounterVec
+}
+
+func (m *metrics) IncrementDNSUDPRequests() {
+	m.dnsResolverRequests.WithLabelValues("udp").Inc()
+}
+
+func (m *metrics) IncrementDNSTCPRequests() {
+	m.dnsResolverRequests.WithLabelValues("tcp").Inc()
+}
+
+func NewMetrics(registerer prometheus.Registerer) Metrics {
+	m := &metrics{
+		dnsResolverRequests: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: subsystem,
+			Name:      "dns_requests_total",
+			Help:      "Total count of DNS requests that have been proxied to the virtual DNS resolver origin",
+		}, []string{"protocol"}),
+	}
+	registerer.MustRegister(m.dnsResolverRequests)
+	return m
+}

ingress/origins/metrics_test.go

@@ -0,0 +1,6 @@
+package origins
+
+type noopMetrics struct{}
+
+func (noopMetrics) IncrementDNSUDPRequests() {}
+func (noopMetrics) IncrementDNSTCPRequests() {}