appc,*: publish events for route updates and storage (#17392)

Add and wire up event publishers for these two event types in the AppConnector.
Nothing currently subscribes to them, so this is harmless. Subscribers for
these events will be added in a near-future commit.

As part of this, move the appc.RouteInfo type to the types/appctype package.
It does not contain any package-specific details from appc. Beside it, add
appctype.RouteUpdate to carry route update event state, likewise not specific
to appc.  Update all usage of the appc.* types throughout to use appctype.*
instead, and update depaware files to reflect these changes.

Add a Close method to the AppConnector to make sure the client gets cleaned up
when the connector is dropped (we re-create connectors).

Update the unit tests in the appc package to also check the events published
alongside calls to the RouteAdvertiser.

For now the tests still rely on the RouteAdvertiser for correctness; this is OK
for now as the two methods are always performed together.  In the near future,
we need to rework the tests so not require that, but that will require building
some more test fixtures that we can handle separately.

Updates #15160
Updates #17192

Change-Id: I184670ba2fb920e0d2cb2be7c6816259bca77afe
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>

appc/appconnector.go

@@ -12,12 +12,14 @@ package appc
 import (
 	"context"
 	"fmt"
+	"maps"
 	"net/netip"
 	"slices"
 	"strings"
 	"sync"
 	"time"
 
+	"tailscale.com/types/appctype"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/views"
 	"tailscale.com/util/clientmetric"
@@ -114,19 +116,6 @@ func metricStoreRoutes(rate, nRoutes int64) {
 	recordMetric(nRoutes, metricStoreRoutesNBuckets, metricStoreRoutesN)
 }
 
-// RouteInfo is a data structure used to persist the in memory state of an AppConnector
-// so that we can know, even after a restart, which routes came from ACLs and which were
-// learned from domains.
-type RouteInfo struct {
-	// Control is the routes from the 'routes' section of an app connector acl.
-	Control []netip.Prefix `json:",omitempty"`
-	// Domains are the routes discovered by observing DNS lookups for configured domains.
-	Domains map[string][]netip.Addr `json:",omitempty"`
-	// Wildcards are the configured DNS lookup domains to observe. When a DNS query matches Wildcards,
-	// its result is added to Domains.
-	Wildcards []string `json:",omitempty"`
-}
-
 // AppConnector is an implementation of an AppConnector that performs
 // its function as a subsystem inside of a tailscale node. At the control plane
 // side App Connector routing is configured in terms of domains rather than IP
@@ -141,9 +130,12 @@ type AppConnector struct {
 	logf            logger.Logf
 	eventBus        *eventbus.Bus
 	routeAdvertiser RouteAdvertiser
+	pubClient       *eventbus.Client
+	updatePub       *eventbus.Publisher[appctype.RouteUpdate]
+	storePub        *eventbus.Publisher[appctype.RouteInfo]
 
 	// storeRoutesFunc will be called to persist routes if it is not nil.
-	storeRoutesFunc func(*RouteInfo) error
+	storeRoutesFunc func(*appctype.RouteInfo) error
 
 	// mu guards the fields that follow
 	mu sync.Mutex
@@ -181,11 +173,11 @@ type Config struct {
 
 	// RouteInfo, if non-nil, use used as the initial set of routes for the
 	// connector.  If nil, the connector starts empty.
-	RouteInfo *RouteInfo
+	RouteInfo *appctype.RouteInfo
 
 	// StoreRoutesFunc, if non-nil, is called when the connector's routes
 	// change, to allow the routes to be persisted.
-	StoreRoutesFunc func(*RouteInfo) error
+	StoreRoutesFunc func(*appctype.RouteInfo) error
 }
 
 // NewAppConnector creates a new AppConnector.
@@ -198,10 +190,14 @@ func NewAppConnector(c Config) *AppConnector {
 	case c.RouteAdvertiser == nil:
 		panic("missing route advertiser")
 	}
+	ec := c.EventBus.Client("appc.AppConnector")
 
 	ac := &AppConnector{
 		logf:            logger.WithPrefix(c.Logf, "appc: "),
 		eventBus:        c.EventBus,
+		pubClient:       ec,
+		updatePub:       eventbus.Publish[appctype.RouteUpdate](ec),
+		storePub:        eventbus.Publish[appctype.RouteInfo](ec),
 		routeAdvertiser: c.RouteAdvertiser,
 		storeRoutesFunc: c.StoreRoutesFunc,
 	}
@@ -228,6 +224,14 @@ func (e *AppConnector) ShouldStoreRoutes() bool {
 
 // storeRoutesLocked takes the current state of the AppConnector and persists it
 func (e *AppConnector) storeRoutesLocked() error {
+	if e.storePub.ShouldPublish() {
+		e.storePub.Publish(appctype.RouteInfo{
+			// Clone here, as the subscriber will handle these outside our lock.
+			Control:   slices.Clone(e.controlRoutes),
+			Domains:   maps.Clone(e.domains),
+			Wildcards: slices.Clone(e.wildcards),
+		})
+	}
 	if !e.ShouldStoreRoutes() {
 		return nil
 	}
@@ -240,7 +244,8 @@ func (e *AppConnector) storeRoutesLocked() error {
 	e.writeRateMinute.update(numRoutes)
 	e.writeRateDay.update(numRoutes)
 
-	return e.storeRoutesFunc(&RouteInfo{
+	// TODO(creachdair): Remove this once it's delivered over the event bus.
+	return e.storeRoutesFunc(&appctype.RouteInfo{
 		Control:   e.controlRoutes,
 		Domains:   e.domains,
 		Wildcards: e.wildcards,
@@ -283,6 +288,18 @@ func (e *AppConnector) Wait(ctx context.Context) {
 	e.queue.Wait(ctx)
 }
 
+// Close closes the connector and cleans up resources associated with it.
+// It is safe (and a noop) to call Close on nil.
+func (e *AppConnector) Close() {
+	if e == nil {
+		return
+	}
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.queue.Shutdown() // TODO(creachadair): Should we wait for it too?
+	e.pubClient.Close()
+}
+
 func (e *AppConnector) updateDomains(domains []string) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
@@ -323,11 +340,15 @@ func (e *AppConnector) updateDomains(domains []string) {
 				toRemove = append(toRemove, netip.PrefixFrom(a, a.BitLen()))
 			}
 		}
-		e.queue.Add(func() {
-			if err := e.routeAdvertiser.UnadvertiseRoute(toRemove...); err != nil {
-				e.logf("failed to unadvertise routes on domain removal: %v: %v: %v", slicesx.MapKeys(oldDomains), toRemove, err)
-			}
-		})
+
+		if len(toRemove) != 0 {
+			e.queue.Add(func() {
+				if err := e.routeAdvertiser.UnadvertiseRoute(toRemove...); err != nil {
+					e.logf("failed to unadvertise routes on domain removal: %v: %v: %v", slicesx.MapKeys(oldDomains), toRemove, err)
+				}
+			})
+			e.updatePub.Publish(appctype.RouteUpdate{Unadvertise: toRemove})
+		}
 	}
 
 	e.logf("handling domains: %v and wildcards: %v", slicesx.MapKeys(e.domains), e.wildcards)
@@ -377,6 +398,10 @@ nextRoute:
 			e.logf("failed to unadvertise routes: %v: %v", toRemove, err)
 		}
 	})
+	e.updatePub.Publish(appctype.RouteUpdate{
+		Advertise:   routes,
+		Unadvertise: toRemove,
+	})
 
 	e.controlRoutes = routes
 	if err := e.storeRoutesLocked(); err != nil {
@@ -464,6 +489,7 @@ func (e *AppConnector) scheduleAdvertisement(domain string, routes ...netip.Pref
 			e.logf("failed to advertise routes for %s: %v: %v", domain, routes, err)
 			return
 		}
+		e.updatePub.Publish(appctype.RouteUpdate{Advertise: routes})
 		e.mu.Lock()
 		defer e.mu.Unlock()
 

appc/appconnector_test.go

@@ -4,6 +4,8 @@
 package appc
 
 import (
+	stdcmp "cmp"
+	"fmt"
 	"net/netip"
 	"reflect"
 	"slices"
@@ -11,9 +13,12 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 	"golang.org/x/net/dns/dnsmessage"
 	"tailscale.com/appc/appctest"
 	"tailscale.com/tstest"
+	"tailscale.com/types/appctype"
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/util/eventbus/eventbustest"
 	"tailscale.com/util/mak"
@@ -21,7 +26,7 @@ import (
 	"tailscale.com/util/slicesx"
 )
 
-func fakeStoreRoutes(*RouteInfo) error { return nil }
+func fakeStoreRoutes(*appctype.RouteInfo) error { return nil }
 
 func TestUpdateDomains(t *testing.T) {
 	ctx := t.Context()
@@ -33,14 +38,15 @@ func TestUpdateDomains(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: &appctest.RouteCollector{},
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: &appctest.RouteCollector{}})
 		}
-		a.UpdateDomains([]string{"example.com"})
+		t.Cleanup(a.Close)
 
+		a.UpdateDomains([]string{"example.com"})
 		a.Wait(ctx)
 		if got, want := a.Domains().AsSlice(), []string{"example.com"}; !slices.Equal(got, want) {
 			t.Errorf("got %v; want %v", got, want)
@@ -68,6 +74,7 @@ func TestUpdateRoutes(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 		var a *AppConnector
 		if shouldStore {
@@ -75,11 +82,14 @@ func TestUpdateRoutes(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{}, StoreRoutesFunc: fakeStoreRoutes,
+				RouteInfo:       &appctype.RouteInfo{},
+				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
+
 		a.updateDomains([]string{"*.example.com"})
 
 		// This route should be collapsed into the range
@@ -116,6 +126,20 @@ func TestUpdateRoutes(t *testing.T) {
 		if !slices.EqualFunc(rc.RemovedRoutes(), wantRemoved, prefixEqual) {
 			t.Fatalf("unexpected removed routes: %v", rc.RemovedRoutes())
 		}
+
+		if err := eventbustest.Expect(w,
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.2.1/32")}),
+			eventbustest.Type[appctype.RouteInfo](),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.0.1/32")}),
+			eventbustest.Type[appctype.RouteInfo](),
+			eqUpdate(appctype.RouteUpdate{
+				Advertise:   prefixes("192.0.0.1/32", "192.0.2.0/24"),
+				Unadvertise: prefixes("192.0.2.1/32"),
+			}),
+			eventbustest.Type[appctype.RouteInfo](),
+		); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -123,6 +147,7 @@ func TestUpdateRoutesUnadvertisesContainedRoutes(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 		var a *AppConnector
 		if shouldStore {
@@ -130,12 +155,14 @@ func TestUpdateRoutesUnadvertisesContainedRoutes(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
+
 		mak.Set(&a.domains, "example.com", []netip.Addr{netip.MustParseAddr("192.0.2.1")})
 		rc.SetRoutes([]netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")})
 		routes := []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")}
@@ -145,12 +172,23 @@ func TestUpdateRoutesUnadvertisesContainedRoutes(t *testing.T) {
 		if !slices.EqualFunc(routes, rc.Routes(), prefixEqual) {
 			t.Fatalf("got %v, want %v", rc.Routes(), routes)
 		}
+
+		if err := eventbustest.ExpectExactly(w,
+			eqUpdate(appctype.RouteUpdate{
+				Advertise:   prefixes("192.0.2.0/24"),
+				Unadvertise: prefixes("192.0.2.1/32"),
+			}),
+			eventbustest.Type[appctype.RouteInfo](),
+		); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
 func TestDomainRoutes(t *testing.T) {
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 		var a *AppConnector
 		if shouldStore {
@@ -158,12 +196,13 @@ func TestDomainRoutes(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
 		a.updateDomains([]string{"example.com"})
 		if err := a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8")); err != nil {
 			t.Errorf("ObserveDNSResponse: %v", err)
@@ -177,6 +216,13 @@ func TestDomainRoutes(t *testing.T) {
 		if got := a.DomainRoutes(); !reflect.DeepEqual(got, want) {
 			t.Fatalf("DomainRoutes: got %v, want %v", got, want)
 		}
+
+		if err := eventbustest.ExpectExactly(w,
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.0.8/32")}),
+			eventbustest.Type[appctype.RouteInfo](),
+		); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -184,6 +230,7 @@ func TestObserveDNSResponse(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 		var a *AppConnector
 		if shouldStore {
@@ -191,12 +238,13 @@ func TestObserveDNSResponse(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
 
 		// a has no domains configured, so it should not advertise any routes
 		if err := a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8")); err != nil {
@@ -273,6 +321,22 @@ func TestObserveDNSResponse(t *testing.T) {
 		if !slices.Contains(a.domains["example.com"], netip.MustParseAddr("192.0.2.1")) {
 			t.Errorf("missing %v from %v", "192.0.2.1", a.domains["exmaple.com"])
 		}
+
+		if err := eventbustest.ExpectExactly(w,
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.0.8/32")}), // from initial DNS response, via example.com
+			eventbustest.Type[appctype.RouteInfo](),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.0.9/32")}), // from CNAME response
+			eventbustest.Type[appctype.RouteInfo](),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.0.10/32")}), // from CNAME response, mid-chain
+			eventbustest.Type[appctype.RouteInfo](),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("2001:db8::1/128")}), // v6 DNS response
+			eventbustest.Type[appctype.RouteInfo](),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.2.0/24")}), // additional prefix
+			eventbustest.Type[appctype.RouteInfo](),
+			// N.B. no update for 192.0.2.1 as it is already covered
+		); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -280,6 +344,7 @@ func TestWildcardDomains(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 		var a *AppConnector
 		if shouldStore {
@@ -287,12 +352,13 @@ func TestWildcardDomains(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
 
 		a.updateDomains([]string{"*.example.com"})
 		if err := a.ObserveDNSResponse(dnsResponse("foo.example.com.", "192.0.0.8")); err != nil {
@@ -319,6 +385,13 @@ func TestWildcardDomains(t *testing.T) {
 		if len(a.wildcards) != 1 {
 			t.Errorf("expected only one wildcard domain, got %v", a.wildcards)
 		}
+
+		if err := eventbustest.ExpectExactly(w,
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("192.0.0.8/32")}),
+			eventbustest.Type[appctype.RouteInfo](),
+		); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -437,6 +510,7 @@ func TestUpdateRouteRouteRemoval(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 
 		assertRoutes := func(prefix string, routes, removedRoutes []netip.Prefix) {
@@ -454,12 +528,14 @@ func TestUpdateRouteRouteRemoval(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
+
 		// nothing has yet been advertised
 		assertRoutes("appc init", []netip.Prefix{}, []netip.Prefix{})
 
@@ -482,6 +558,13 @@ func TestUpdateRouteRouteRemoval(t *testing.T) {
 			wantRemovedRoutes = prefixes("1.2.3.2/32")
 		}
 		assertRoutes("removal", wantRoutes, wantRemovedRoutes)
+
+		if err := eventbustest.Expect(w,
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.1/32", "1.2.3.2/32")}), // no duplicates here
+			eventbustest.Type[appctype.RouteInfo](),
+		); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -489,6 +572,7 @@ func TestUpdateDomainRouteRemoval(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 
 		assertRoutes := func(prefix string, routes, removedRoutes []netip.Prefix) {
@@ -506,12 +590,14 @@ func TestUpdateDomainRouteRemoval(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
+
 		assertRoutes("appc init", []netip.Prefix{}, []netip.Prefix{})
 
 		a.UpdateDomainsAndRoutes([]string{"a.example.com", "b.example.com"}, []netip.Prefix{})
@@ -544,6 +630,22 @@ func TestUpdateDomainRouteRemoval(t *testing.T) {
 			wantRemovedRoutes = prefixes("1.2.3.3/32", "1.2.3.4/32")
 		}
 		assertRoutes("removal", wantRoutes, wantRemovedRoutes)
+
+		wantEvents := []any{
+			// Each DNS record observed triggers an update.
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.1/32")}),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.2/32")}),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.3/32")}),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.4/32")}),
+		}
+		if shouldStore {
+			wantEvents = append(wantEvents, eqUpdate(appctype.RouteUpdate{
+				Unadvertise: prefixes("1.2.3.3/32", "1.2.3.4/32"),
+			}))
+		}
+		if err := eventbustest.Expect(w, wantEvents...); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -551,6 +653,7 @@ func TestUpdateWildcardRouteRemoval(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
 	for _, shouldStore := range []bool{false, true} {
+		w := eventbustest.NewWatcher(t, bus)
 		rc := &appctest.RouteCollector{}
 
 		assertRoutes := func(prefix string, routes, removedRoutes []netip.Prefix) {
@@ -568,12 +671,14 @@ func TestUpdateWildcardRouteRemoval(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			a = NewAppConnector(Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
 		}
+		t.Cleanup(a.Close)
+
 		assertRoutes("appc init", []netip.Prefix{}, []netip.Prefix{})
 
 		a.UpdateDomainsAndRoutes([]string{"a.example.com", "*.b.example.com"}, []netip.Prefix{})
@@ -606,6 +711,22 @@ func TestUpdateWildcardRouteRemoval(t *testing.T) {
 			wantRemovedRoutes = prefixes("1.2.3.3/32", "1.2.3.4/32")
 		}
 		assertRoutes("removal", wantRoutes, wantRemovedRoutes)
+
+		wantEvents := []any{
+			// Each DNS record observed triggers an update.
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.1/32")}),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.2/32")}),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.3/32")}),
+			eqUpdate(appctype.RouteUpdate{Advertise: prefixes("1.2.3.4/32")}),
+		}
+		if shouldStore {
+			wantEvents = append(wantEvents, eqUpdate(appctype.RouteUpdate{
+				Unadvertise: prefixes("1.2.3.3/32", "1.2.3.4/32"),
+			}))
+		}
+		if err := eventbustest.Expect(w, wantEvents...); err != nil {
+			t.Error(err)
+		}
 	}
 }
 
@@ -708,17 +829,23 @@ func TestMetricBucketsAreSorted(t *testing.T) {
 // routeAdvertiser, calls to Advertise/UnadvertiseRoutes can end up calling
 // back into AppConnector via authReconfig. If everything is called
 // synchronously, this results in a deadlock on AppConnector.mu.
+//
+// TODO(creachadair, 2025-09-18): Remove this along with the advertiser
+// interface once the LocalBackend is switched to use the event bus and the
+// tests have been updated not to need it.
 func TestUpdateRoutesDeadlock(t *testing.T) {
 	ctx := t.Context()
 	bus := eventbustest.NewBus(t)
+	w := eventbustest.NewWatcher(t, bus)
 	rc := &appctest.RouteCollector{}
 	a := NewAppConnector(Config{
 		Logf:            t.Logf,
 		EventBus:        bus,
 		RouteAdvertiser: rc,
-		RouteInfo:       &RouteInfo{},
+		RouteInfo:       &appctype.RouteInfo{},
 		StoreRoutesFunc: fakeStoreRoutes,
 	})
+	t.Cleanup(a.Close)
 
 	advertiseCalled := new(atomic.Bool)
 	unadvertiseCalled := new(atomic.Bool)
@@ -762,4 +889,42 @@ func TestUpdateRoutesDeadlock(t *testing.T) {
 	if want := []netip.Prefix{netip.MustParsePrefix("127.0.0.1/32")}; !slices.Equal(slices.Compact(rc.Routes()), want) {
 		t.Fatalf("got %v, want %v", rc.Routes(), want)
 	}
+
+	if err := eventbustest.ExpectExactly(w,
+		eqUpdate(appctype.RouteUpdate{Advertise: prefixes("127.0.0.1/32", "127.0.0.2/32")}),
+		eventbustest.Type[appctype.RouteInfo](),
+		eqUpdate(appctype.RouteUpdate{Advertise: prefixes("127.0.0.1/32"), Unadvertise: prefixes("127.0.0.2/32")}),
+		eventbustest.Type[appctype.RouteInfo](),
+	); err != nil {
+		t.Error(err)
+	}
+}
+
+type textUpdate struct {
+	Advertise   []string
+	Unadvertise []string
+}
+
+func routeUpdateToText(u appctype.RouteUpdate) textUpdate {
+	var out textUpdate
+	for _, p := range u.Advertise {
+		out.Advertise = append(out.Advertise, p.String())
+	}
+	for _, p := range u.Unadvertise {
+		out.Unadvertise = append(out.Unadvertise, p.String())
+	}
+	return out
+}
+
+// eqUpdate generates an eventbus test filter that matches a appctype.RouteUpdate
+// message equal to want, or reports an error giving a human-readable diff.
+func eqUpdate(want appctype.RouteUpdate) func(appctype.RouteUpdate) error {
+	return func(got appctype.RouteUpdate) error {
+		if diff := cmp.Diff(routeUpdateToText(got), routeUpdateToText(want),
+			cmpopts.SortSlices(stdcmp.Less[string]),
+		); diff != "" {
+			return fmt.Errorf("wrong update (-got, +want):\n%s", diff)
+		}
+		return nil
+	}
 }

client/local/local.go

@@ -27,7 +27,6 @@ import (
 	"sync"
 	"time"
 
-	"tailscale.com/appc"
 	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/drive"
 	"tailscale.com/envknob"
@@ -40,6 +39,7 @@ import (
 	"tailscale.com/paths"
 	"tailscale.com/safesocket"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/appctype"
 	"tailscale.com/types/dnstype"
 	"tailscale.com/types/key"
 	"tailscale.com/util/eventbus"
@@ -1387,10 +1387,10 @@ func (lc *Client) ShutdownTailscaled(ctx context.Context) error {
 	return err
 }
 
-func (lc *Client) GetAppConnectorRouteInfo(ctx context.Context) (appc.RouteInfo, error) {
+func (lc *Client) GetAppConnectorRouteInfo(ctx context.Context) (appctype.RouteInfo, error) {
 	body, err := lc.get200(ctx, "/localapi/v0/appc-route-info")
 	if err != nil {
-		return appc.RouteInfo{}, err
+		return appctype.RouteInfo{}, err
 	}
-	return decodeJSON[appc.RouteInfo](body)
+	return decodeJSON[appctype.RouteInfo](body)
 }

cmd/derper/depaware.txt

@@ -74,7 +74,6 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         google.golang.org/protobuf/runtime/protoimpl                 from github.com/prometheus/client_model/go+
         google.golang.org/protobuf/types/known/timestamppb           from github.com/prometheus/client_golang/prometheus+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/client/local
      💣 tailscale.com/atomicfile                                     from tailscale.com/cmd/derper+
         tailscale.com/client/local                                   from tailscale.com/derp/derpserver
         tailscale.com/client/tailscale/apitype                       from tailscale.com/client/local
@@ -124,6 +123,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/tsweb                                          from tailscale.com/cmd/derper+
         tailscale.com/tsweb/promvarz                                 from tailscale.com/cmd/derper
         tailscale.com/tsweb/varz                                     from tailscale.com/tsweb+
+        tailscale.com/types/appctype                                 from tailscale.com/client/local
         tailscale.com/types/dnstype                                  from tailscale.com/tailcfg+
         tailscale.com/types/empty                                    from tailscale.com/ipn
         tailscale.com/types/ipproto                                  from tailscale.com/tailcfg+
@@ -140,14 +140,13 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/types/tkatype                                  from tailscale.com/client/local+
         tailscale.com/types/views                                    from tailscale.com/ipn+
         tailscale.com/util/cibuild                                   from tailscale.com/health
-        tailscale.com/util/clientmetric                              from tailscale.com/net/netmon+
+        tailscale.com/util/clientmetric                              from tailscale.com/net/netmon
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/ctxkey                                    from tailscale.com/tsweb+
      💣 tailscale.com/util/deephash                                  from tailscale.com/util/syspolicy/setting
    L 💣 tailscale.com/util/dirwalk                                   from tailscale.com/metrics
         tailscale.com/util/dnsname                                   from tailscale.com/hostinfo+
         tailscale.com/util/eventbus                                  from tailscale.com/net/netmon+
-        tailscale.com/util/execqueue                                 from tailscale.com/appc
      💣 tailscale.com/util/hashx                                     from tailscale.com/util/deephash
         tailscale.com/util/lineiter                                  from tailscale.com/hostinfo+
         tailscale.com/util/mak                                       from tailscale.com/health+
@@ -183,7 +182,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         golang.org/x/exp/constraints                                 from tailscale.com/util/winutil+
         golang.org/x/exp/maps                                        from tailscale.com/util/syspolicy/setting
    L    golang.org/x/net/bpf                                         from github.com/mdlayher/netlink+
-        golang.org/x/net/dns/dnsmessage                              from tailscale.com/appc+
+        golang.org/x/net/dns/dnsmessage                              from tailscale.com/net/dnscache
         golang.org/x/net/idna                                        from golang.org/x/crypto/acme/autocert
         golang.org/x/net/internal/socks                              from golang.org/x/net/proxy
         golang.org/x/net/proxy                                       from tailscale.com/net/netns

cmd/k8s-operator/depaware.txt

@@ -679,7 +679,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         sigs.k8s.io/yaml                                             from k8s.io/apimachinery/pkg/runtime/serializer/json+
         sigs.k8s.io/yaml/goyaml.v2                                   from sigs.k8s.io/yaml+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal+
+        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal
      💣 tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/local                                   from tailscale.com/client/tailscale+
         tailscale.com/client/tailscale                               from tailscale.com/cmd/k8s-operator+
@@ -802,7 +802,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter
         tailscale.com/tsweb                                          from tailscale.com/util/eventbus
         tailscale.com/tsweb/varz                                     from tailscale.com/util/usermetric+
-        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal
+        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/bools                                    from tailscale.com/tsnet
         tailscale.com/types/dnstype                                  from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/empty                                    from tailscale.com/ipn+

cmd/tailscale/cli/appcroutes.go

@@ -12,7 +12,7 @@ import (
 	"strings"
 
 	"github.com/peterbourgon/ff/v3/ffcli"
-	"tailscale.com/appc"
+	"tailscale.com/types/appctype"
 )
 
 var appcRoutesArgs struct {
@@ -51,7 +51,7 @@ https://tailscale.com/kb/1281/app-connectors
 `),
 }
 
-func getAllOutput(ri *appc.RouteInfo) (string, error) {
+func getAllOutput(ri *appctype.RouteInfo) (string, error) {
 	domains, err := json.MarshalIndent(ri.Domains, " ", "  ")
 	if err != nil {
 		return "", err
@@ -76,7 +76,7 @@ type domainCount struct {
 	count  int
 }
 
-func getSummarizeLearnedOutput(ri *appc.RouteInfo) string {
+func getSummarizeLearnedOutput(ri *appctype.RouteInfo) string {
 	x := make([]domainCount, len(ri.Domains))
 	i := 0
 	maxDomainWidth := 0

cmd/tailscale/depaware.txt

@@ -73,7 +73,6 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         software.sslmate.com/src/go-pkcs12                           from tailscale.com/cmd/tailscale/cli
         software.sslmate.com/src/go-pkcs12/internal/rc2              from software.sslmate.com/src/go-pkcs12
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/client/local+
      💣 tailscale.com/atomicfile                                     from tailscale.com/cmd/tailscale/cli+
         tailscale.com/client/local                                   from tailscale.com/client/tailscale+
    L    tailscale.com/client/systray                                 from tailscale.com/cmd/tailscale/cli
@@ -150,6 +149,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/tstime/rate                                    from tailscale.com/cmd/tailscale/cli
         tailscale.com/tsweb                                          from tailscale.com/util/eventbus
         tailscale.com/tsweb/varz                                     from tailscale.com/util/usermetric+
+        tailscale.com/types/appctype                                 from tailscale.com/client/local+
         tailscale.com/types/dnstype                                  from tailscale.com/tailcfg+
         tailscale.com/types/empty                                    from tailscale.com/ipn
         tailscale.com/types/ipproto                                  from tailscale.com/ipn+
@@ -175,7 +175,6 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    L 💣 tailscale.com/util/dirwalk                                   from tailscale.com/metrics
         tailscale.com/util/dnsname                                   from tailscale.com/cmd/tailscale/cli+
         tailscale.com/util/eventbus                                  from tailscale.com/client/local+
-        tailscale.com/util/execqueue                                 from tailscale.com/appc
         tailscale.com/util/groupmember                               from tailscale.com/client/web
      💣 tailscale.com/util/hashx                                     from tailscale.com/util/deephash
         tailscale.com/util/httpm                                     from tailscale.com/client/tailscale+
@@ -232,7 +231,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    L    golang.org/x/image/math/f64                                  from github.com/fogleman/gg+
    L    golang.org/x/image/math/fixed                                from github.com/fogleman/gg+
         golang.org/x/net/bpf                                         from github.com/mdlayher/netlink+
-        golang.org/x/net/dns/dnsmessage                              from tailscale.com/appc+
+        golang.org/x/net/dns/dnsmessage                              from tailscale.com/cmd/tailscale/cli+
         golang.org/x/net/http/httpproxy                              from tailscale.com/net/tshttpproxy
         golang.org/x/net/icmp                                        from tailscale.com/net/ping
         golang.org/x/net/idna                                        from golang.org/x/net/http/httpproxy+

cmd/tailscaled/depaware-min.txt

@@ -35,7 +35,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
      💣 go4.org/mem                                                  from tailscale.com/control/controlbase+
         go4.org/netipx                                               from tailscale.com/ipn/ipnlocal+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal+
+        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal
         tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/tailscale/apitype                       from tailscale.com/ipn/ipnauth+
         tailscale.com/cmd/tailscaled/childproc                       from tailscale.com/cmd/tailscaled
@@ -126,7 +126,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/tstime/mono                                    from tailscale.com/net/tstun+
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter
         tailscale.com/tsweb/varz                                     from tailscale.com/cmd/tailscaled+
-        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal
+        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/dnstype                                  from tailscale.com/client/tailscale/apitype+
         tailscale.com/types/empty                                    from tailscale.com/ipn+
         tailscale.com/types/flagtype                                 from tailscale.com/cmd/tailscaled

cmd/tailscaled/depaware-minbox.txt

@@ -48,7 +48,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
      💣 go4.org/mem                                                  from tailscale.com/control/controlbase+
         go4.org/netipx                                               from tailscale.com/ipn/ipnlocal+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal+
+        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal
         tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/local                                   from tailscale.com/client/tailscale+
         tailscale.com/client/tailscale                               from tailscale.com/internal/client/tailscale
@@ -151,7 +151,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/tstime/mono                                    from tailscale.com/net/tstun+
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter
         tailscale.com/tsweb/varz                                     from tailscale.com/cmd/tailscaled+
-        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal
+        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/dnstype                                  from tailscale.com/client/tailscale/apitype+
         tailscale.com/types/empty                                    from tailscale.com/ipn+
         tailscale.com/types/flagtype                                 from tailscale.com/cmd/tailscaled

cmd/tailscaled/depaware.txt

@@ -240,7 +240,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         gvisor.dev/gvisor/pkg/tcpip/transport/udp                    from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
         gvisor.dev/gvisor/pkg/waiter                                 from gvisor.dev/gvisor/pkg/context+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal+
+        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal
      💣 tailscale.com/atomicfile                                     from tailscale.com/ipn+
   LD    tailscale.com/chirp                                          from tailscale.com/cmd/tailscaled
         tailscale.com/client/local                                   from tailscale.com/client/web+
@@ -387,7 +387,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter
         tailscale.com/tsweb                                          from tailscale.com/util/eventbus
         tailscale.com/tsweb/varz                                     from tailscale.com/cmd/tailscaled+
-        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal
+        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/dnstype                                  from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/empty                                    from tailscale.com/ipn+
         tailscale.com/types/flagtype                                 from tailscale.com/cmd/tailscaled

cmd/tsidp/depaware.txt

@@ -121,7 +121,7 @@ tailscale.com/cmd/tsidp dependencies: (generated by github.com/tailscale/depawar
         gvisor.dev/gvisor/pkg/tcpip/transport/udp                    from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
         gvisor.dev/gvisor/pkg/waiter                                 from gvisor.dev/gvisor/pkg/context+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal+
+        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal
      💣 tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/local                                   from tailscale.com/client/web+
         tailscale.com/client/tailscale                               from tailscale.com/internal/client/tailscale
@@ -229,7 +229,7 @@ tailscale.com/cmd/tsidp dependencies: (generated by github.com/tailscale/depawar
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter
         tailscale.com/tsweb                                          from tailscale.com/util/eventbus
         tailscale.com/tsweb/varz                                     from tailscale.com/tsweb+
-        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal
+        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/bools                                    from tailscale.com/tsnet
         tailscale.com/types/dnstype                                  from tailscale.com/client/local+
         tailscale.com/types/empty                                    from tailscale.com/ipn+

ipn/ipnlocal/local.go

@@ -1108,6 +1108,7 @@ func (b *LocalBackend) Shutdown() {
 	if b.notifyCancel != nil {
 		b.notifyCancel()
 	}
+	b.appConnector.Close()
 	b.mu.Unlock()
 	b.webClientShutdown()
 
@@ -4783,25 +4784,28 @@ func (b *LocalBackend) reconfigAppConnectorLocked(nm *netmap.NetworkMap, prefs i
 	}()
 
 	if !prefs.AppConnector().Advertise {
+		b.appConnector.Close() // clean up a previous connector (safe on nil)
 		b.appConnector = nil
 		return
 	}
 
 	shouldAppCStoreRoutes := b.ControlKnobs().AppCStoreRoutes.Load()
 	if b.appConnector == nil || b.appConnector.ShouldStoreRoutes() != shouldAppCStoreRoutes {
-		var ri *appc.RouteInfo
-		var storeFunc func(*appc.RouteInfo) error
+		var ri *appctype.RouteInfo
+		var storeFunc func(*appctype.RouteInfo) error
 		if shouldAppCStoreRoutes {
 			var err error
 			ri, err = b.readRouteInfoLocked()
 			if err != nil {
-				ri = &appc.RouteInfo{}
+				ri = &appctype.RouteInfo{}
 				if err != ipn.ErrStateNotExist {
 					b.logf("Unsuccessful Read RouteInfo: ", err)
 				}
 			}
 			storeFunc = b.storeRouteInfo
 		}
+
+		b.appConnector.Close() // clean up a previous connector (safe on nil)
 		b.appConnector = appc.NewAppConnector(appc.Config{
 			Logf:            b.logf,
 			EventBus:        b.sys.Bus.Get(),
@@ -6988,7 +6992,7 @@ func namespaceKeyForCurrentProfile(pm *profileManager, key ipn.StateKey) ipn.Sta
 
 const routeInfoStateStoreKey ipn.StateKey = "_routeInfo"
 
-func (b *LocalBackend) storeRouteInfo(ri *appc.RouteInfo) error {
+func (b *LocalBackend) storeRouteInfo(ri *appctype.RouteInfo) error {
 	if !buildfeatures.HasAppConnectors {
 		return feature.ErrUnavailable
 	}
@@ -7005,16 +7009,16 @@ func (b *LocalBackend) storeRouteInfo(ri *appc.RouteInfo) error {
 	return b.pm.WriteState(key, bs)
 }
 
-func (b *LocalBackend) readRouteInfoLocked() (*appc.RouteInfo, error) {
+func (b *LocalBackend) readRouteInfoLocked() (*appctype.RouteInfo, error) {
 	if !buildfeatures.HasAppConnectors {
 		return nil, feature.ErrUnavailable
 	}
 	if b.pm.CurrentProfile().ID() == "" {
-		return &appc.RouteInfo{}, nil
+		return &appctype.RouteInfo{}, nil
 	}
 	key := namespaceKeyForCurrentProfile(b.pm, routeInfoStateStoreKey)
 	bs, err := b.pm.Store().ReadState(key)
-	ri := &appc.RouteInfo{}
+	ri := &appctype.RouteInfo{}
 	if err != nil {
 		return nil, err
 	}
@@ -7027,7 +7031,7 @@ func (b *LocalBackend) readRouteInfoLocked() (*appc.RouteInfo, error) {
 // ReadRouteInfo returns the app connector route information that is
 // stored in prefs to be consistent across restarts. It should be up
 // to date with the RouteInfo in memory being used by appc.
-func (b *LocalBackend) ReadRouteInfo() (*appc.RouteInfo, error) {
+func (b *LocalBackend) ReadRouteInfo() (*appctype.RouteInfo, error) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 	return b.readRouteInfoLocked()

ipn/ipnlocal/local_test.go

@@ -49,6 +49,7 @@ import (
 	"tailscale.com/tsd"
 	"tailscale.com/tstest"
 	"tailscale.com/tstest/deptest"
+	"tailscale.com/types/appctype"
 	"tailscale.com/types/dnstype"
 	"tailscale.com/types/ipproto"
 	"tailscale.com/types/key"
@@ -74,7 +75,7 @@ import (
 	"tailscale.com/wgengine/wgcfg"
 )
 
-func fakeStoreRoutes(*appc.RouteInfo) error { return nil }
+func fakeStoreRoutes(*appctype.RouteInfo) error { return nil }
 
 func inRemove(ip netip.Addr) bool {
 	for _, pfx := range removeFromDefaultRoute {
@@ -2314,7 +2315,7 @@ func TestOfferingAppConnector(t *testing.T) {
 		rc := &appctest.RouteCollector{}
 		if shouldStore {
 			b.appConnector = appc.NewAppConnector(appc.Config{
-				Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc, RouteInfo: &appc.RouteInfo{}, StoreRoutesFunc: fakeStoreRoutes,
+				Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc, RouteInfo: &appctype.RouteInfo{}, StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
 			b.appConnector = appc.NewAppConnector(appc.Config{Logf: t.Logf, EventBus: bus, RouteAdvertiser: rc})
@@ -2381,7 +2382,7 @@ func TestObserveDNSResponse(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        bus,
 				RouteAdvertiser: rc,
-				RouteInfo:       &appc.RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
@@ -2548,7 +2549,7 @@ func TestBackfillAppConnectorRoutes(t *testing.T) {
 
 	// Store the test IP in profile data, but not in Prefs.AdvertiseRoutes.
 	b.ControlKnobs().AppCStoreRoutes.Store(true)
-	if err := b.storeRouteInfo(&appc.RouteInfo{
+	if err := b.storeRouteInfo(&appctype.RouteInfo{
 		Domains: map[string][]netip.Addr{
 			"example.com": {ip},
 		},
@@ -5501,10 +5502,10 @@ func TestReadWriteRouteInfo(t *testing.T) {
 	b.pm.currentProfile = prof1.View()
 
 	// set up routeInfo
-	ri1 := &appc.RouteInfo{}
+	ri1 := &appctype.RouteInfo{}
 	ri1.Wildcards = []string{"1"}
 
-	ri2 := &appc.RouteInfo{}
+	ri2 := &appctype.RouteInfo{}
 	ri2.Wildcards = []string{"2"}
 
 	// read before write

ipn/ipnlocal/peerapi_test.go

@@ -23,6 +23,7 @@ import (
 	"tailscale.com/tailcfg"
 	"tailscale.com/tsd"
 	"tailscale.com/tstest"
+	"tailscale.com/types/appctype"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/netmap"
 	"tailscale.com/util/eventbus/eventbustest"
@@ -261,7 +262,7 @@ func TestPeerAPIPrettyReplyCNAME(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        sys.Bus.Get(),
 				RouteAdvertiser: &appctest.RouteCollector{},
-				RouteInfo:       &appc.RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
@@ -346,7 +347,7 @@ func TestPeerAPIReplyToDNSQueriesAreObserved(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        sys.Bus.Get(),
 				RouteAdvertiser: rc,
-				RouteInfo:       &appc.RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {
@@ -419,7 +420,7 @@ func TestPeerAPIReplyToDNSQueriesAreObservedWithCNAMEFlattening(t *testing.T) {
 				Logf:            t.Logf,
 				EventBus:        sys.Bus.Get(),
 				RouteAdvertiser: rc,
-				RouteInfo:       &appc.RouteInfo{},
+				RouteInfo:       &appctype.RouteInfo{},
 				StoreRoutesFunc: fakeStoreRoutes,
 			})
 		} else {

ipn/localapi/localapi.go

@@ -23,7 +23,6 @@ import (
 	"time"
 
 	"golang.org/x/net/dns/dnsmessage"
-	"tailscale.com/appc"
 	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/envknob"
 	"tailscale.com/feature"
@@ -38,6 +37,7 @@ import (
 	"tailscale.com/net/netutil"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tstime"
+	"tailscale.com/types/appctype"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/logid"
@@ -1684,7 +1684,7 @@ func (h *Handler) serveGetAppcRouteInfo(w http.ResponseWriter, r *http.Request)
 	res, err := h.b.ReadRouteInfo()
 	if err != nil {
 		if errors.Is(err, ipn.ErrStateNotExist) {
-			res = &appc.RouteInfo{}
+			res = &appctype.RouteInfo{}
 		} else {
 			WriteErrorJSON(w, err)
 			return

tsnet/depaware.txt

@@ -117,7 +117,7 @@ tailscale.com/tsnet dependencies: (generated by github.com/tailscale/depaware)
         gvisor.dev/gvisor/pkg/tcpip/transport/udp                    from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
         gvisor.dev/gvisor/pkg/waiter                                 from gvisor.dev/gvisor/pkg/context+
         tailscale.com                                                from tailscale.com/version
-        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal+
+        tailscale.com/appc                                           from tailscale.com/ipn/ipnlocal
      💣 tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/local                                   from tailscale.com/client/web+
         tailscale.com/client/tailscale                               from tailscale.com/internal/client/tailscale
@@ -224,7 +224,7 @@ tailscale.com/tsnet dependencies: (generated by github.com/tailscale/depaware)
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter
  LDW    tailscale.com/tsweb                                          from tailscale.com/util/eventbus
         tailscale.com/tsweb/varz                                     from tailscale.com/tsweb+
-        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal
+        tailscale.com/types/appctype                                 from tailscale.com/ipn/ipnlocal+
         tailscale.com/types/bools                                    from tailscale.com/tsnet
         tailscale.com/types/dnstype                                  from tailscale.com/client/local+
         tailscale.com/types/empty                                    from tailscale.com/ipn+

types/appctype/appconnector.go

@@ -73,3 +73,23 @@ type AppConnectorAttr struct {
 	// tag of the form tag:<tag-name>.
 	Connectors []string `json:"connectors,omitempty"`
 }
+
+// RouteInfo is a data structure used to persist the in memory state of an AppConnector
+// so that we can know, even after a restart, which routes came from ACLs and which were
+// learned from domains.
+type RouteInfo struct {
+	// Control is the routes from the 'routes' section of an app connector acl.
+	Control []netip.Prefix `json:",omitempty"`
+	// Domains are the routes discovered by observing DNS lookups for configured domains.
+	Domains map[string][]netip.Addr `json:",omitempty"`
+	// Wildcards are the configured DNS lookup domains to observe. When a DNS query matches Wildcards,
+	// its result is added to Domains.
+	Wildcards []string `json:",omitempty"`
+}
+
+// RouteUpdate records a set of routes that should be advertised and a set of
+// routes that should be unadvertised in event bus updates.
+type RouteUpdate struct {
+	Advertise   []netip.Prefix
+	Unadvertise []netip.Prefix
+}