Support proxy_server_ready_backends metric

cmd/server/app/options/options.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/klog/v2"
 
 	"sigs.k8s.io/apiserver-network-proxy/pkg/server"
+	"sigs.k8s.io/apiserver-network-proxy/pkg/server/proxystrategies"
 	"sigs.k8s.io/apiserver-network-proxy/pkg/util"
 )
 
@@ -314,7 +315,7 @@ func (o *ProxyRunOptions) Validate() error {
 	if len(o.ProxyStrategies) == 0 {
 		return fmt.Errorf("ProxyStrategies cannot be empty")
 	}
-	if _, err := server.ParseProxyStrategies(o.ProxyStrategies); err != nil {
+	if _, err := proxystrategies.ParseProxyStrategies(o.ProxyStrategies); err != nil {
 		return fmt.Errorf("invalid proxy strategies: %v", err)
 	}
 	if o.XfrChannelSize <= 0 {

cmd/server/app/server.go

@@ -46,6 +46,7 @@ import (
 	"sigs.k8s.io/apiserver-network-proxy/konnectivity-client/proto/client"
 	"sigs.k8s.io/apiserver-network-proxy/pkg/server"
 	"sigs.k8s.io/apiserver-network-proxy/pkg/server/leases"
+	"sigs.k8s.io/apiserver-network-proxy/pkg/server/proxystrategies"
 	"sigs.k8s.io/apiserver-network-proxy/pkg/util"
 	"sigs.k8s.io/apiserver-network-proxy/proto/agent"
 )
@@ -134,7 +135,7 @@ func (p *Proxy) Run(o *options.ProxyRunOptions, stopCh <-chan struct{}) error {
 		AuthenticationAudience: o.AuthenticationAudience,
 	}
 	klog.V(1).Infoln("Starting frontend server for client connections.")
-	ps, err := server.ParseProxyStrategies(o.ProxyStrategies)
+	ps, err := proxystrategies.ParseProxyStrategies(o.ProxyStrategies)
 	if err != nil {
 		return err
 	}

pkg/server/backend_manager.go

@@ -22,7 +22,6 @@ import (
 	"io"
 	"math/rand"
 	"slices"
-	"strings"
 	"sync"
 	"time"
 
@@ -32,72 +31,11 @@ import (
 	commonmetrics "sigs.k8s.io/apiserver-network-proxy/konnectivity-client/pkg/common/metrics"
 	client "sigs.k8s.io/apiserver-network-proxy/konnectivity-client/proto/client"
 	"sigs.k8s.io/apiserver-network-proxy/pkg/server/metrics"
+	"sigs.k8s.io/apiserver-network-proxy/pkg/server/proxystrategies"
 	"sigs.k8s.io/apiserver-network-proxy/proto/agent"
 	"sigs.k8s.io/apiserver-network-proxy/proto/header"
 )
 
-type ProxyStrategy int
-
-const (
-	// With this strategy the Proxy Server will randomly pick a backend from
-	// the current healthy backends to establish the tunnel over which to
-	// forward requests.
-	ProxyStrategyDefault ProxyStrategy = iota + 1
-	// With this strategy the Proxy Server will pick a backend that has the same
-	// associated host as the request.Host to establish the tunnel.
-	ProxyStrategyDestHost
-	// ProxyStrategyDefaultRoute will only forward traffic to agents that have explicity advertised
-	// they serve the default route through an agent identifier. Typically used in combination with destHost
-	ProxyStrategyDefaultRoute
-)
-
-func (ps ProxyStrategy) String() string {
-	switch ps {
-	case ProxyStrategyDefault:
-		return "default"
-	case ProxyStrategyDestHost:
-		return "destHost"
-	case ProxyStrategyDefaultRoute:
-		return "defaultRoute"
-	}
-	panic(fmt.Sprintf("unhandled ProxyStrategy: %d", ps))
-}
-
-func ParseProxyStrategy(s string) (ProxyStrategy, error) {
-	switch s {
-	case ProxyStrategyDefault.String():
-		return ProxyStrategyDefault, nil
-	case ProxyStrategyDestHost.String():
-		return ProxyStrategyDestHost, nil
-	case ProxyStrategyDefaultRoute.String():
-		return ProxyStrategyDefaultRoute, nil
-	default:
-		return 0, fmt.Errorf("unknown proxy strategy: %s", s)
-	}
-}
-
-// GenProxyStrategiesFromStr generates the list of proxy strategies from the
-// comma-seperated string, i.e., destHost.
-func ParseProxyStrategies(proxyStrategies string) ([]ProxyStrategy, error) {
-	var result []ProxyStrategy
-
-	strs := strings.Split(proxyStrategies, ",")
-	for _, s := range strs {
-		if len(s) == 0 {
-			continue
-		}
-		ps, err := ParseProxyStrategy(s)
-		if err != nil {
-			return nil, err
-		}
-		result = append(result, ps)
-	}
-	if len(result) == 0 {
-		return nil, fmt.Errorf("proxy strategies cannot be empty")
-	}
-	return result, nil
-}
-
 // Backend abstracts a connected Konnectivity agent.
 //
 // In the only currently supported case (gRPC), it wraps an
@@ -271,24 +209,31 @@ type DefaultBackendStorage struct {
 	// e.g., when associating to the DestHostBackendManager, it can only use the
 	// identifiers of types, IPv4, IPv6 and Host.
 	idTypes []header.IdentifierType
+	// proxyStrategy is the proxy strategy of the backend manager this storage
+	// belongs to.
+	// It is used to record metrics.
+	proxyStrategy proxystrategies.ProxyStrategy
 }
 
 // NewDefaultBackendManager returns a DefaultBackendManager.
 func NewDefaultBackendManager() *DefaultBackendManager {
 	return &DefaultBackendManager{
 		DefaultBackendStorage: NewDefaultBackendStorage(
-			[]header.IdentifierType{header.UID})}
+			[]header.IdentifierType{header.UID}, proxystrategies.ProxyStrategyDefault)}
 }
 
 // NewDefaultBackendStorage returns a DefaultBackendStorage
-func NewDefaultBackendStorage(idTypes []header.IdentifierType) *DefaultBackendStorage {
+func NewDefaultBackendStorage(idTypes []header.IdentifierType, proxyStrategy proxystrategies.ProxyStrategy) *DefaultBackendStorage {
 	// Set an explicit value, so that the metric is emitted even when
 	// no agent ever successfully connects.
-	metrics.Metrics.SetBackendCount(0)
+	metrics.Metrics.SetBackendCountDeprecated(0)
+	metrics.Metrics.SetTotalBackendCount(proxyStrategy, 0)
+
 	return &DefaultBackendStorage{
-		backends: make(map[string][]*Backend),
-		random:   rand.New(rand.NewSource(time.Now().UnixNano())), /* #nosec G404 */
-		idTypes:  idTypes,
+		backends:      make(map[string][]*Backend),
+		random:        rand.New(rand.NewSource(time.Now().UnixNano())), /* #nosec G404 */
+		idTypes:       idTypes,
+		proxyStrategy: proxyStrategy,
 	}
 }
 
@@ -317,7 +262,8 @@ func (s *DefaultBackendStorage) addBackend(identifier string, idType header.Iden
 		return
 	}
 	s.backends[identifier] = []*Backend{backend}
-	metrics.Metrics.SetBackendCount(len(s.backends))
+	metrics.Metrics.SetBackendCountDeprecated(len(s.backends))
+	metrics.Metrics.SetTotalBackendCount(s.proxyStrategy, len(s.backends))
 	s.agentIDs = append(s.agentIDs, identifier)
 }
 
@@ -358,7 +304,8 @@ func (s *DefaultBackendStorage) removeBackend(identifier string, idType header.I
 	if !found {
 		klog.V(1).InfoS("Could not find connection matching identifier to remove", "agentID", identifier, "idType", idType)
 	}
-	metrics.Metrics.SetBackendCount(len(s.backends))
+	metrics.Metrics.SetBackendCountDeprecated(len(s.backends))
+	metrics.Metrics.SetTotalBackendCount(s.proxyStrategy, len(s.backends))
 }
 
 // NumBackends resturns the number of available backends

pkg/server/backend_manager_test.go

@@ -18,11 +18,9 @@ package server
 
 import (
 	"context"
-	"fmt"
 	"reflect"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"go.uber.org/mock/gomock"
 	"google.golang.org/grpc/metadata"
 
@@ -385,123 +383,3 @@ func TestDestHostBackendManager_WithDuplicateIdents(t *testing.T) {
 		t.Errorf("expected %v, got %v", e, a)
 	}
 }
-
-func TestProxyStrategy(t *testing.T) {
-	for desc, tc := range map[string]struct {
-		input     ProxyStrategy
-		want      string
-		wantPanic string
-	}{
-		"default": {
-			input: ProxyStrategyDefault,
-			want:  "default",
-		},
-		"destHost": {
-			input: ProxyStrategyDestHost,
-			want:  "destHost",
-		},
-		"defaultRoute": {
-			input: ProxyStrategyDefaultRoute,
-			want:  "defaultRoute",
-		},
-		"unrecognized": {
-			input:     ProxyStrategy(0),
-			wantPanic: "unhandled ProxyStrategy: 0",
-		},
-	} {
-		t.Run(desc, func(t *testing.T) {
-			if tc.wantPanic != "" {
-				assert.PanicsWithValue(t, tc.wantPanic, func() {
-					_ = tc.input.String()
-				})
-			} else {
-				got := tc.input.String()
-				if got != tc.want {
-					t.Errorf("ProxyStrategy.String(): got %v, want %v", got, tc.want)
-				}
-			}
-		})
-	}
-}
-
-func TestParseProxyStrategy(t *testing.T) {
-	for desc, tc := range map[string]struct {
-		input   string
-		want    ProxyStrategy
-		wantErr error
-	}{
-		"empty": {
-			input:   "",
-			wantErr: fmt.Errorf("unknown proxy strategy: "),
-		},
-		"unrecognized": {
-			input:   "unrecognized",
-			wantErr: fmt.Errorf("unknown proxy strategy: unrecognized"),
-		},
-		"default": {
-			input: "default",
-			want:  ProxyStrategyDefault,
-		},
-		"destHost": {
-			input: "destHost",
-			want:  ProxyStrategyDestHost,
-		},
-		"defaultRoute": {
-			input: "defaultRoute",
-			want:  ProxyStrategyDefaultRoute,
-		},
-	} {
-		t.Run(desc, func(t *testing.T) {
-			got, err := ParseProxyStrategy(tc.input)
-			assert.Equal(t, tc.wantErr, err, "ParseProxyStrategy(%s): got error %q, want %v", tc.input, err, tc.wantErr)
-			if got != tc.want {
-				t.Errorf("ParseProxyStrategy(%s): got %v, want %v", tc.input, got, tc.want)
-			}
-		})
-	}
-}
-
-func TestParseProxyStrategies(t *testing.T) {
-	for desc, tc := range map[string]struct {
-		input   string
-		want    []ProxyStrategy
-		wantErr error
-	}{
-		"empty": {
-			input:   "",
-			wantErr: fmt.Errorf("proxy strategies cannot be empty"),
-		},
-		"unrecognized": {
-			input:   "unrecognized",
-			wantErr: fmt.Errorf("unknown proxy strategy: unrecognized"),
-		},
-		"default": {
-			input: "default",
-			want:  []ProxyStrategy{ProxyStrategyDefault},
-		},
-		"destHost": {
-			input: "destHost",
-			want:  []ProxyStrategy{ProxyStrategyDestHost},
-		},
-		"defaultRoute": {
-			input: "defaultRoute",
-			want:  []ProxyStrategy{ProxyStrategyDefaultRoute},
-		},
-		"duplicate": {
-			input: "destHost,defaultRoute,defaultRoute,default",
-			want:  []ProxyStrategy{ProxyStrategyDestHost, ProxyStrategyDefaultRoute, ProxyStrategyDefaultRoute, ProxyStrategyDefault},
-		},
-		"multiple": {
-			input: "destHost,defaultRoute,default",
-			want:  []ProxyStrategy{ProxyStrategyDestHost, ProxyStrategyDefaultRoute, ProxyStrategyDefault},
-		},
-	} {
-		t.Run(desc, func(t *testing.T) {
-			got, err := ParseProxyStrategies(tc.input)
-			assert.Equal(t, tc.wantErr, err, "ParseProxyStrategies(%s): got error %q, want %v", tc.input, err, tc.wantErr)
-			if !reflect.DeepEqual(got, tc.want) {
-				t.Errorf("ParseProxyStrategies(%s): got %v, want %v", tc.input, got, tc.want)
-			}
-		})
-	}
-}

pkg/server/default_route_backend_manager.go

@@ -20,6 +20,7 @@ import (
 	"context"
 
 	"k8s.io/klog/v2"
+	"sigs.k8s.io/apiserver-network-proxy/pkg/server/proxystrategies"
 	"sigs.k8s.io/apiserver-network-proxy/proto/header"
 )
 
@@ -32,7 +33,7 @@ var _ BackendManager = &DefaultRouteBackendManager{}
 func NewDefaultRouteBackendManager() *DefaultRouteBackendManager {
 	return &DefaultRouteBackendManager{
 		DefaultBackendStorage: NewDefaultBackendStorage(
-			[]header.IdentifierType{header.DefaultRoute})}
+			[]header.IdentifierType{header.DefaultRoute}, proxystrategies.ProxyStrategyDefaultRoute)}
 }
 
 // Backend tries to get a backend that advertises default route, with random selection.

pkg/server/desthost_backend_manager.go

@@ -20,6 +20,7 @@ import (
 	"context"
 
 	"k8s.io/klog/v2"
+	"sigs.k8s.io/apiserver-network-proxy/pkg/server/proxystrategies"
 	"sigs.k8s.io/apiserver-network-proxy/proto/header"
 )
 
@@ -32,7 +33,7 @@ var _ BackendManager = &DestHostBackendManager{}
 func NewDestHostBackendManager() *DestHostBackendManager {
 	return &DestHostBackendManager{
 		DefaultBackendStorage: NewDefaultBackendStorage(
-			[]header.IdentifierType{header.IPv4, header.IPv6, header.Host})}
+			[]header.IdentifierType{header.IPv4, header.IPv6, header.Host}, proxystrategies.ProxyStrategyDestHost)}
 }
 
 func (dibm *DestHostBackendManager) AddBackend(backend *Backend) {