cmd/containerboot,kube: enable autoadvertisement of Tailscale services on containerboot (#18527)

* cmd/containerboot,kube/services: support the ability to automatically advertise services on startup

Updates #17769

Signed-off-by: chaosinthecrd <tom@tmlabs.co.uk>

* cmd/containerboot: don't assume we want to use kube state store if in kubernetes

Fixes #8188

Signed-off-by: chaosinthecrd <tom@tmlabs.co.uk>

---------

Signed-off-by: chaosinthecrd <tom@tmlabs.co.uk>

cmd/containerboot/main.go

@@ -101,6 +101,10 @@
 //     cluster using the same hostname (in this case, the MagicDNS name of the ingress proxy)
 //     as a non-cluster workload on tailnet.
 //     This is only meant to be configured by the Kubernetes operator.
+//   - TS_EXPERIMENTAL_SERVICE_AUTO_ADVERTISEMENT: If set to true and if this
+//     containerboot instance is not running in Kubernetes, autoadvertise any services
+//     defined in the devices serve config, and unadvertise on shutdown. Defaults
+//     to `true`, but can be disabled to allow user specific advertisement configuration.
 //
 // When running on Kubernetes, containerboot defaults to storing state in the
 // "tailscale" kube secret. To store state on local disk instead, set
@@ -137,6 +141,7 @@ import (
 	kubeutils "tailscale.com/k8s-operator"
 	healthz "tailscale.com/kube/health"
 	"tailscale.com/kube/kubetypes"
+	klc "tailscale.com/kube/localclient"
 	"tailscale.com/kube/metrics"
 	"tailscale.com/kube/services"
 	"tailscale.com/tailcfg"
@@ -155,6 +160,10 @@ func newNetfilterRunner(logf logger.Logf) (linuxfw.NetfilterRunner, error) {
 	return linuxfw.New(logf, "")
 }
 
+func getAutoAdvertiseBool() bool {
+	return defaultBool("TS_EXPERIMENTAL_SERVICE_AUTO_ADVERTISEMENT", true)
+}
+
 func main() {
 	if err := run(); err != nil && !errors.Is(err, context.Canceled) {
 		log.Fatal(err)
@@ -199,7 +208,7 @@ func run() error {
 	defer cancel()
 
 	var kc *kubeClient
-	if cfg.InKubernetes {
+	if cfg.KubeSecret != "" {
 		kc, err = newKubeClient(cfg.Root, cfg.KubeSecret)
 		if err != nil {
 			return fmt.Errorf("error initializing kube client: %w", err)
@@ -229,6 +238,7 @@ func run() error {
 		ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
 		defer cancel()
 
+		// we are shutting down, we always want to unadvertise here
 		if err := services.EnsureServicesNotAdvertised(ctx, client, log.Printf); err != nil {
 			log.Printf("Error ensuring services are not advertised: %v", err)
 		}
@@ -652,9 +662,22 @@ runLoop:
 					healthCheck.Update(len(addrs) != 0)
 				}
 
+				var prevServeConfig *ipn.ServeConfig
+				if getAutoAdvertiseBool() {
+					prevServeConfig, err = client.GetServeConfig(ctx)
+					if err != nil {
+						return fmt.Errorf("autoadvertisement: failed to get serve config: %w", err)
+					}
+
+					err = refreshAdvertiseServices(ctx, prevServeConfig, klc.New(client))
+					if err != nil {
+						return fmt.Errorf("autoadvertisement: failed to refresh advertise services: %w", err)
+					}
+				}
+
 				if cfg.ServeConfigPath != "" {
 					triggerWatchServeConfigChanges.Do(func() {
-						go watchServeConfigChanges(ctx, certDomainChanged, certDomain, client, kc, cfg)
+						go watchServeConfigChanges(ctx, certDomainChanged, certDomain, client, kc, cfg, prevServeConfig)
 					})
 				}
 

cmd/containerboot/main_test.go

@@ -1009,6 +1009,25 @@ func TestContainerBoot(t *testing.T) {
 				},
 			}
 		},
+		"serve_config_with_service_auto_advertisement": func(env *testEnv) testCase {
+			return testCase{
+				Env: map[string]string{
+					"TS_SERVE_CONFIG": filepath.Join(env.d, "etc/tailscaled/serve-config-with-services.json"),
+					"TS_AUTHKEY":      "tskey-key",
+				},
+				Phases: []phase{
+					{
+						WantCmds: []string{
+							"/usr/bin/tailscaled --socket=/tmp/tailscaled.sock --state=mem: --statedir=/tmp --tun=userspace-networking",
+							"/usr/bin/tailscale --socket=/tmp/tailscaled.sock up --accept-dns=false --authkey=tskey-key",
+						},
+					},
+					{
+						Notify: runningNotify,
+					},
+				},
+			}
+		},
 		"kube_shutdown_during_state_write": func(env *testEnv) testCase {
 			return testCase{
 				Env: map[string]string{
@@ -1159,7 +1178,7 @@ func TestContainerBoot(t *testing.T) {
 					return nil
 				})
 				if err != nil {
-					t.Fatalf("phase %d: %v", i, err)
+					t.Fatalf("test: %q phase %d: %v", name, i, err)
 				}
 				err = tstest.WaitFor(2*time.Second, func() error {
 					for path, want := range p.WantFiles {
@@ -1340,10 +1359,16 @@ func (lc *localAPI) Notify(n *ipn.Notify) {
 func (lc *localAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	switch r.URL.Path {
 	case "/localapi/v0/serve-config":
-		if r.Method != "POST" {
+		switch r.Method {
+		case "GET":
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(&ipn.ServeConfig{})
+			return
+		case "POST":
+			return
+		default:
 			panic(fmt.Sprintf("unsupported method %q", r.Method))
 		}
-		return
 	case "/localapi/v0/watch-ipn-bus":
 		if r.Method != "GET" {
 			panic(fmt.Sprintf("unsupported method %q", r.Method))
@@ -1355,10 +1380,19 @@ func (lc *localAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("fake metrics"))
 		return
 	case "/localapi/v0/prefs":
-		if r.Method != "GET" {
+		switch r.Method {
+		case "GET":
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(&ipn.Prefs{})
+			return
+		case "PATCH":
+			// EditPrefs - just return empty prefs
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(&ipn.Prefs{})
+			return
+		default:
 			panic(fmt.Sprintf("unsupported method %q", r.Method))
 		}
-		return
 	default:
 		panic(fmt.Sprintf("unsupported path %q", r.URL.Path))
 	}
@@ -1635,6 +1669,13 @@ func newTestEnv(t *testing.T) testEnv {
 
 	tailscaledConf := &ipn.ConfigVAlpha{AuthKey: ptr.To("foo"), Version: "alpha0"}
 	serveConf := ipn.ServeConfig{TCP: map[uint16]*ipn.TCPPortHandler{80: {HTTP: true}}}
+	serveConfWithServices := ipn.ServeConfig{
+		TCP: map[uint16]*ipn.TCPPortHandler{80: {HTTP: true}},
+		Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
+			"svc:test-service-1": {},
+			"svc:test-service-2": {},
+		},
+	}
 	egressCfg := egressSvcConfig("foo", "foo.tailnetxyz.ts.net")
 
 	dirs := []string{
@@ -1661,6 +1702,7 @@ func newTestEnv(t *testing.T) testEnv {
 		"proc/sys/net/ipv6/conf/all/forwarding":          []byte("0"),
 		"etc/tailscaled/cap-95.hujson":                   mustJSON(t, tailscaledConf),
 		"etc/tailscaled/serve-config.json":               mustJSON(t, serveConf),
+		"etc/tailscaled/serve-config-with-services.json": mustJSON(t, serveConfWithServices),
 		filepath.Join("etc/tailscaled/", egressservices.KeyEgressServices): mustJSON(t, egressCfg),
 		filepath.Join("etc/tailscaled/", egressservices.KeyHEPPings):       []byte("4"),
 	}

cmd/containerboot/serve.go

@@ -9,6 +9,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"fmt"
 	"log"
 	"os"
 	"path/filepath"
@@ -22,6 +23,7 @@ import (
 	"tailscale.com/kube/certs"
 	"tailscale.com/kube/kubetypes"
 	klc "tailscale.com/kube/localclient"
+	"tailscale.com/kube/services"
 	"tailscale.com/types/netmap"
 )
 
@@ -29,8 +31,9 @@ import (
 // the serve config from it, replacing ${TS_CERT_DOMAIN} with certDomain, and
 // applies it to lc. It exits when ctx is canceled. cdChanged is a channel that
 // is written to when the certDomain changes, causing the serve config to be
-// re-read and applied.
-func watchServeConfigChanges(ctx context.Context, cdChanged <-chan bool, certDomainAtomic *atomic.Pointer[string], lc *local.Client, kc *kubeClient, cfg *settings) {
+// re-read and applied. prevServeConfig is the serve config that was fetched
+// during startup. This will be refreshed by the goroutine when serve config changes.
+func watchServeConfigChanges(ctx context.Context, cdChanged <-chan bool, certDomainAtomic *atomic.Pointer[string], lc *local.Client, kc *kubeClient, cfg *settings, prevServeConfig *ipn.ServeConfig) {
 	if certDomainAtomic == nil {
 		panic("certDomainAtomic must not be nil")
 	}
@@ -53,11 +56,18 @@ func watchServeConfigChanges(ctx context.Context, cdChanged <-chan bool, certDom
 	}
 
 	var certDomain string
-	var prevServeConfig *ipn.ServeConfig
 	var cm *certs.CertManager
 	if cfg.CertShareMode == "rw" {
 		cm = certs.NewCertManager(klc.New(lc), log.Printf)
 	}
+
+	var err error
+	if prevServeConfig == nil {
+		prevServeConfig, err = lc.GetServeConfig(ctx)
+		if err != nil {
+			log.Fatalf("serve proxy: failed to get serve config: %v", err)
+		}
+	}
 	for {
 		select {
 		case <-ctx.Done():
@@ -70,6 +80,9 @@ func watchServeConfigChanges(ctx context.Context, cdChanged <-chan bool, certDom
 			// k8s handles these mounts. So just re-read the file and apply it
 			// if it's changed.
 		}
+
+		var sc *ipn.ServeConfig
+		if cfg.ServeConfigPath != "" {
 			sc, err := readServeConfig(cfg.ServeConfigPath, certDomain)
 			if err != nil {
 				log.Fatalf("serve proxy: failed to read serve config: %v", err)
@@ -81,7 +94,7 @@ func watchServeConfigChanges(ctx context.Context, cdChanged <-chan bool, certDom
 			if prevServeConfig != nil && reflect.DeepEqual(sc, prevServeConfig) {
 				continue
 			}
-		if err := updateServeConfig(ctx, sc, certDomain, lc); err != nil {
+			if err := updateServeConfig(ctx, sc, certDomain, klc.New(lc)); err != nil {
 				log.Fatalf("serve proxy: error updating serve config: %v", err)
 			}
 			if kc != nil && kc.canPatch {
@@ -96,9 +109,39 @@ func watchServeConfigChanges(ctx context.Context, cdChanged <-chan bool, certDom
 			if err := cm.EnsureCertLoops(ctx, sc); err != nil {
 				log.Fatalf("serve proxy: error ensuring cert loops: %v", err)
 			}
+		} else {
+			log.Printf("serve config path not provided.")
+			sc = prevServeConfig
+		}
+
+		// if we are running in kubernetes, we want to leave advertisement to the operator
+		// to do (by updating the serve config)
+		if getAutoAdvertiseBool() {
+			if err := refreshAdvertiseServices(ctx, sc, klc.New(lc)); err != nil {
+				log.Fatalf("error refreshing advertised services: %v", err)
+			}
+		}
 	}
 }
 
+func refreshAdvertiseServices(ctx context.Context, sc *ipn.ServeConfig, lc klc.LocalClient) error {
+	if sc == nil || len(sc.Services) == 0 {
+		return nil
+	}
+
+	var svcs []string
+	for svc := range sc.Services {
+		svcs = append(svcs, svc.String())
+	}
+
+	err := services.EnsureServicesAdvertised(ctx, svcs, lc, log.Printf)
+	if err != nil {
+		return fmt.Errorf("failed to ensure services advertised: %w", err)
+	}
+
+	return nil
+}
+
 func certDomainFromNetmap(nm *netmap.NetworkMap) string {
 	if len(nm.DNS.CertDomains) == 0 {
 		return ""
@@ -106,13 +149,7 @@ func certDomainFromNetmap(nm *netmap.NetworkMap) string {
 	return nm.DNS.CertDomains[0]
 }
 
-// localClient is a subset of [local.Client] that can be mocked for testing.
-type localClient interface {
-	SetServeConfig(context.Context, *ipn.ServeConfig) error
-	CertPair(context.Context, string) ([]byte, []byte, error)
-}
-
-func updateServeConfig(ctx context.Context, sc *ipn.ServeConfig, certDomain string, lc localClient) error {
+func updateServeConfig(ctx context.Context, sc *ipn.ServeConfig, certDomain string, lc klc.LocalClient) error {
 	if !isValidHTTPSConfig(certDomain, sc) {
 		return nil
 	}

cmd/containerboot/serve_test.go

@@ -12,9 +12,10 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
-	"tailscale.com/client/local"
 	"tailscale.com/ipn"
 	"tailscale.com/kube/kubetypes"
+	"tailscale.com/kube/localclient"
+	"tailscale.com/tailcfg"
 )
 
 func TestUpdateServeConfig(t *testing.T) {
@@ -65,13 +66,13 @@ func TestUpdateServeConfig(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			fakeLC := &fakeLocalClient{}
+			fakeLC := &localclient.FakeLocalClient{}
 			err := updateServeConfig(context.Background(), tt.sc, tt.certDomain, fakeLC)
 			if err != nil {
 				t.Errorf("updateServeConfig() error = %v", err)
 			}
-			if fakeLC.setServeCalled != tt.wantCall {
-				t.Errorf("SetServeConfig() called = %v, want %v", fakeLC.setServeCalled, tt.wantCall)
+			if fakeLC.SetServeCalled != tt.wantCall {
+				t.Errorf("SetServeConfig() called = %v, want %v", fakeLC.SetServeCalled, tt.wantCall)
 			}
 		})
 	}
@@ -196,18 +197,114 @@ func TestReadServeConfig(t *testing.T) {
 	}
 }
 
-type fakeLocalClient struct {
-	*local.Client
-	setServeCalled bool
-}
+func TestRefreshAdvertiseServices(t *testing.T) {
+	tests := []struct {
+		name                string
+		sc                  *ipn.ServeConfig
+		wantServices        []string
+		wantEditPrefsCalled bool
+		wantErr             bool
+	}{
+		{
+			name:                "nil_serve_config",
+			sc:                  nil,
+			wantEditPrefsCalled: false,
+		},
+		{
+			name:                "empty_serve_config",
+			sc:                  &ipn.ServeConfig{},
+			wantEditPrefsCalled: false,
+		},
+		{
+			name: "no_services_defined",
+			sc: &ipn.ServeConfig{
+				TCP: map[uint16]*ipn.TCPPortHandler{
+					80: {HTTP: true},
+				},
+			},
+			wantEditPrefsCalled: false,
+		},
+		{
+			name: "single_service",
+			sc: &ipn.ServeConfig{
+				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
+					"svc:my-service": {},
+				},
+			},
+			wantServices:        []string{"svc:my-service"},
+			wantEditPrefsCalled: true,
+		},
+		{
+			name: "multiple_services",
+			sc: &ipn.ServeConfig{
+				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
+					"svc:service-a": {},
+					"svc:service-b": {},
+					"svc:service-c": {},
+				},
+			},
+			wantServices:        []string{"svc:service-a", "svc:service-b", "svc:service-c"},
+			wantEditPrefsCalled: true,
+		},
+		{
+			name: "services_with_tcp_and_web",
+			sc: &ipn.ServeConfig{
+				TCP: map[uint16]*ipn.TCPPortHandler{
+					80: {HTTP: true},
+				},
+				Web: map[ipn.HostPort]*ipn.WebServerConfig{
+					"example.com:443": {},
+				},
+				Services: map[tailcfg.ServiceName]*ipn.ServiceConfig{
+					"svc:frontend": {},
+					"svc:backend":  {},
+				},
+			},
+			wantServices:        []string{"svc:frontend", "svc:backend"},
+			wantEditPrefsCalled: true,
+		},
+	}
 
-func (m *fakeLocalClient) SetServeConfig(ctx context.Context, cfg *ipn.ServeConfig) error {
-	m.setServeCalled = true
-	return nil
-}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fakeLC := &localclient.FakeLocalClient{}
+			err := refreshAdvertiseServices(context.Background(), tt.sc, fakeLC)
 
-func (m *fakeLocalClient) CertPair(ctx context.Context, domain string) (certPEM, keyPEM []byte, err error) {
-	return nil, nil, nil
+			if (err != nil) != tt.wantErr {
+				t.Errorf("refreshAdvertiseServices() error = %v, wantErr %v", err, tt.wantErr)
+			}
+
+			if tt.wantEditPrefsCalled != (len(fakeLC.EditPrefsCalls) > 0) {
+				t.Errorf("EditPrefs called = %v, want %v", len(fakeLC.EditPrefsCalls) > 0, tt.wantEditPrefsCalled)
+			}
+
+			if tt.wantEditPrefsCalled {
+				if len(fakeLC.EditPrefsCalls) != 1 {
+					t.Fatalf("expected 1 EditPrefs call, got %d", len(fakeLC.EditPrefsCalls))
+				}
+
+				mp := fakeLC.EditPrefsCalls[0]
+				if !mp.AdvertiseServicesSet {
+					t.Error("AdvertiseServicesSet should be true")
+				}
+
+				if len(mp.AdvertiseServices) != len(tt.wantServices) {
+					t.Errorf("AdvertiseServices length = %d, want %d", len(mp.Prefs.AdvertiseServices), len(tt.wantServices))
+				}
+
+				advertised := make(map[string]bool)
+				for _, svc := range mp.AdvertiseServices {
+					advertised[svc] = true
+				}
+
+				for _, want := range tt.wantServices {
+					if !advertised[want] {
+						t.Errorf("expected service %q to be advertised, but it wasn't", want)
+					}
+				}
+			}
+		})
+	}
 }
 
 func TestHasHTTPSEndpoint(t *testing.T) {

cmd/containerboot/settings.go

@@ -107,7 +107,12 @@ func configFromEnv() (*settings, error) {
 		UserspaceMode:                         defaultBool("TS_USERSPACE", true),
 		StateDir:                              defaultEnv("TS_STATE_DIR", ""),
 		AcceptDNS:                             defaultEnvBoolPointer("TS_ACCEPT_DNS"),
-		KubeSecret:                            defaultEnv("TS_KUBE_SECRET", "tailscale"),
+		KubeSecret: func() string {
+			if os.Getenv("KUBERNETES_SERVICE_HOST") != "" {
+				return defaultEnv("TS_KUBE_SECRET", "tailscale")
+			}
+			return defaultEnv("TS_KUBE_SECRET", "")
+		}(),
 		SOCKSProxyAddr:                        defaultEnv("TS_SOCKS5_SERVER", ""),
 		HTTPProxyAddr:                         defaultEnv("TS_OUTBOUND_HTTP_PROXY_LISTEN", ""),
 		Socket:                                defaultEnv("TS_SOCKET", "/tmp/tailscaled.sock"),

cmd/containerboot/tailscaled.go

@@ -69,7 +69,7 @@ func startTailscaled(ctx context.Context, cfg *settings) (*local.Client, *os.Pro
 func tailscaledArgs(cfg *settings) []string {
 	args := []string{"--socket=" + cfg.Socket}
 	switch {
-	case cfg.InKubernetes && cfg.KubeSecret != "":
+	case cfg.KubeSecret != "":
 		args = append(args, "--state=kube:"+cfg.KubeSecret)
 		if cfg.StateDir == "" {
 			cfg.StateDir = "/tmp"

cmd/k8s-operator/proxygroup_specs.go

@@ -173,6 +173,10 @@ func pgStatefulSet(pg *tsapi.ProxyGroup, namespace, image, tsFirewallMode string
 				Name:  "TS_KUBE_SECRET",
 				Value: "$(POD_NAME)",
 			},
+			{
+				Name:  "TS_EXPERIMENTAL_SERVICE_AUTO_ADVERTISEMENT",
+				Value: "false",
+			},
 			{
 				// TODO(tomhjp): This is tsrecorder-specific and does nothing. Delete.
 				Name:  "TS_STATE",

cmd/k8s-operator/sts.go

@@ -692,6 +692,10 @@ func (a *tailscaleSTSReconciler) reconcileSTS(ctx context.Context, logger *zap.S
 			Name:  "TS_KUBE_SECRET",
 			Value: "$(POD_NAME)",
 		},
+		corev1.EnvVar{
+			Name:  "TS_EXPERIMENTAL_SERVICE_AUTO_ADVERTISEMENT",
+			Value: "false",
+		},
 		corev1.EnvVar{
 			Name:  "TS_EXPERIMENTAL_VERSIONED_CONFIG_DIR",
 			Value: "/etc/tsconfig/$(POD_NAME)",

cmd/k8s-operator/testutils_test.go

@@ -91,6 +91,7 @@ func expectedSTS(t *testing.T, cl client.Client, opts configOpts) *appsv1.Statef
 			{Name: "POD_NAME", ValueFrom: &corev1.EnvVarSource{FieldRef: &corev1.ObjectFieldSelector{APIVersion: "", FieldPath: "metadata.name"}, ResourceFieldRef: nil, ConfigMapKeyRef: nil, SecretKeyRef: nil}},
 			{Name: "POD_UID", ValueFrom: &corev1.EnvVarSource{FieldRef: &corev1.ObjectFieldSelector{APIVersion: "", FieldPath: "metadata.uid"}, ResourceFieldRef: nil, ConfigMapKeyRef: nil, SecretKeyRef: nil}},
 			{Name: "TS_KUBE_SECRET", Value: "$(POD_NAME)"},
+			{Name: "TS_EXPERIMENTAL_SERVICE_AUTO_ADVERTISEMENT", Value: "false"},
 			{Name: "TS_EXPERIMENTAL_VERSIONED_CONFIG_DIR", Value: "/etc/tsconfig/$(POD_NAME)"},
 			{Name: "TS_DEBUG_ACME_FORCE_RENEWAL", Value: "true"},
 		},
@@ -287,6 +288,7 @@ func expectedSTSUserspace(t *testing.T, cl client.Client, opts configOpts) *apps
 			{Name: "POD_NAME", ValueFrom: &corev1.EnvVarSource{FieldRef: &corev1.ObjectFieldSelector{APIVersion: "", FieldPath: "metadata.name"}, ResourceFieldRef: nil, ConfigMapKeyRef: nil, SecretKeyRef: nil}},
 			{Name: "POD_UID", ValueFrom: &corev1.EnvVarSource{FieldRef: &corev1.ObjectFieldSelector{APIVersion: "", FieldPath: "metadata.uid"}, ResourceFieldRef: nil, ConfigMapKeyRef: nil, SecretKeyRef: nil}},
 			{Name: "TS_KUBE_SECRET", Value: "$(POD_NAME)"},
+			{Name: "TS_EXPERIMENTAL_SERVICE_AUTO_ADVERTISEMENT", Value: "false"},
 			{Name: "TS_EXPERIMENTAL_VERSIONED_CONFIG_DIR", Value: "/etc/tsconfig/$(POD_NAME)"},
 			{Name: "TS_DEBUG_ACME_FORCE_RENEWAL", Value: "true"},
 			{Name: "TS_SERVE_CONFIG", Value: "/etc/tailscaled/$(POD_NAME)/serve-config"},

kube/localclient/fake-client.go

@@ -12,6 +12,29 @@ import (
 
 type FakeLocalClient struct {
 	FakeIPNBusWatcher
+	SetServeCalled bool
+	EditPrefsCalls []*ipn.MaskedPrefs
+	GetPrefsResult *ipn.Prefs
+}
+
+func (m *FakeLocalClient) SetServeConfig(ctx context.Context, cfg *ipn.ServeConfig) error {
+	m.SetServeCalled = true
+	return nil
+}
+
+func (m *FakeLocalClient) EditPrefs(ctx context.Context, mp *ipn.MaskedPrefs) (*ipn.Prefs, error) {
+	m.EditPrefsCalls = append(m.EditPrefsCalls, mp)
+	if m.GetPrefsResult == nil {
+		return &ipn.Prefs{}, nil
+	}
+	return m.GetPrefsResult, nil
+}
+
+func (m *FakeLocalClient) GetPrefs(ctx context.Context) (*ipn.Prefs, error) {
+	if m.GetPrefsResult == nil {
+		return &ipn.Prefs{}, nil
+	}
+	return m.GetPrefsResult, nil
 }
 
 func (f *FakeLocalClient) WatchIPNBus(ctx context.Context, mask ipn.NotifyWatchOpt) (IPNBusWatcher, error) {

kube/localclient/local-client.go

@@ -17,6 +17,8 @@ import (
 // for easier testing.
 type LocalClient interface {
 	WatchIPNBus(ctx context.Context, mask ipn.NotifyWatchOpt) (IPNBusWatcher, error)
+	SetServeConfig(context.Context, *ipn.ServeConfig) error
+	EditPrefs(ctx context.Context, mp *ipn.MaskedPrefs) (*ipn.Prefs, error)
 	CertIssuer
 }
 
@@ -40,6 +42,14 @@ type localClient struct {
 	lc *local.Client
 }
 
+func (lc *localClient) SetServeConfig(ctx context.Context, config *ipn.ServeConfig) error {
+	return lc.lc.SetServeConfig(ctx, config)
+}
+
+func (lc *localClient) EditPrefs(ctx context.Context, mp *ipn.MaskedPrefs) (*ipn.Prefs, error) {
+	return lc.lc.EditPrefs(ctx, mp)
+}
+
 func (lc *localClient) WatchIPNBus(ctx context.Context, mask ipn.NotifyWatchOpt) (IPNBusWatcher, error) {
 	return lc.lc.WatchIPNBus(ctx, mask)
 }

kube/services/services.go

@@ -12,9 +12,46 @@ import (
 
 	"tailscale.com/client/local"
 	"tailscale.com/ipn"
+	"tailscale.com/kube/localclient"
 	"tailscale.com/types/logger"
 )
 
+// EnsureServicesAdvertised is a function that gets called on containerboot
+// startup and ensures that Services get advertised if they exist.
+func EnsureServicesAdvertised(ctx context.Context, services []string, lc localclient.LocalClient, logf logger.Logf) error {
+	if _, err := lc.EditPrefs(ctx, &ipn.MaskedPrefs{
+		AdvertiseServicesSet: true,
+		Prefs: ipn.Prefs{
+			AdvertiseServices: services,
+		},
+	}); err != nil {
+		// EditPrefs only returns an error if it fails _set_ its local prefs.
+		// If it fails to _persist_ the prefs in state, we don't get an error
+		// and we continue waiting below, as control will failover as usual.
+		return fmt.Errorf("error setting prefs AdvertiseServices: %w", err)
+	}
+
+	// Services use the same (failover XOR regional routing) mechanism that
+	// HA subnet routers use. Unfortunately we don't yet get a reliable signal
+	// from control that it's responded to our unadvertisement, so the best we
+	// can do is wait for 20 seconds, where 15s is the approximate maximum time
+	// it should take for control to choose a new primary, and 5s is for buffer.
+	//
+	// Note: There is no guarantee that clients have been _informed_ of the new
+	// primary no matter how long we wait. We would need a mechanism to await
+	// netmap updates for peers to know for sure.
+	//
+	// See https://tailscale.com/kb/1115/high-availability for more details.
+	// TODO(tomhjp): Wait for a netmap update instead of sleeping when control
+	// supports that.
+	select {
+	case <-ctx.Done():
+		return nil
+	case <-time.After(20 * time.Second):
+		return nil
+	}
+}
+
 // EnsureServicesNotAdvertised is a function that gets called on containerboot
 // or k8s-proxy termination and ensures that any currently advertised Services
 // get unadvertised to give clients time to switch to another node before this