batch updates in notifier (#1905)

hscontrol/app.go

@@ -137,7 +137,7 @@ func NewHeadscale(cfg *types.Config) (*Headscale, error) {
 		noisePrivateKey:    noisePrivateKey,
 		registrationCache:  registrationCache,
 		pollNetMapStreamWG: sync.WaitGroup{},
-		nodeNotifier:       notifier.NewNotifier(),
+		nodeNotifier:       notifier.NewNotifier(cfg),
 		mapSessions:        make(map[types.NodeID]*mapSession),
 	}
 

hscontrol/notifier/metrics.go

@@ -18,7 +18,12 @@ var (
 		Namespace: prometheusNamespace,
 		Name:      "notifier_update_sent_total",
 		Help:      "total count of update sent on nodes channel",
-	}, []string{"status", "type"})
+	}, []string{"status", "type", "trigger"})
+	notifierUpdateReceived = promauto.NewCounterVec(prometheus.CounterOpts{
+		Namespace: prometheusNamespace,
+		Name:      "notifier_update_received_total",
+		Help:      "total count of updates received by notifier",
+	}, []string{"type", "trigger"})
 	notifierNodeUpdateChans = promauto.NewGauge(prometheus.GaugeOpts{
 		Namespace: prometheusNamespace,
 		Name:      "notifier_open_channels_total",

hscontrol/notifier/notifier.go

@@ -3,7 +3,7 @@ package notifier
 import (
 	"context"
 	"fmt"
-	"slices"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -11,19 +11,27 @@ import (
 	"github.com/juanfont/headscale/hscontrol/types"
 	"github.com/puzpuzpuz/xsync/v3"
 	"github.com/rs/zerolog/log"
+	"tailscale.com/tailcfg"
+	"tailscale.com/util/set"
 )
 
 type Notifier struct {
 	l         sync.RWMutex
 	nodes     map[types.NodeID]chan<- types.StateUpdate
 	connected *xsync.MapOf[types.NodeID, bool]
+	b         *batcher
 }
 
-func NewNotifier() *Notifier {
-	return &Notifier{
+func NewNotifier(cfg *types.Config) *Notifier {
+	n := &Notifier{
 		nodes:     make(map[types.NodeID]chan<- types.StateUpdate),
 		connected: xsync.NewMapOf[types.NodeID, bool](),
 	}
+	b := newBatcher(cfg.Tuning.BatchChangeDelay, n)
+	n.b = b
+	// TODO(kradalby): clean this up
+	go b.doWork()
+	return n
 }
 
 func (n *Notifier) AddNode(nodeID types.NodeID, c chan<- types.StateUpdate) {
@@ -108,13 +116,8 @@ func (n *Notifier) NotifyWithIgnore(
 	update types.StateUpdate,
 	ignoreNodeIDs ...types.NodeID,
 ) {
-	for nodeID := range n.nodes {
-		if slices.Contains(ignoreNodeIDs, nodeID) {
-			continue
-		}
-
-		n.NotifyByNodeID(ctx, update, nodeID)
-	}
+	notifierUpdateReceived.WithLabelValues(update.Type.String(), types.NotifyOriginKey.Value(ctx)).Inc()
+	n.b.addOrPassthrough(update)
 }
 
 func (n *Notifier) NotifyByNodeID(
@@ -139,10 +142,10 @@ func (n *Notifier) NotifyByNodeID(
 			log.Error().
 				Err(ctx.Err()).
 				Uint64("node.id", nodeID.Uint64()).
-				Any("origin", ctx.Value("origin")).
-				Any("origin-hostname", ctx.Value("hostname")).
+				Any("origin", types.NotifyOriginKey.Value(ctx)).
+				Any("origin-hostname", types.NotifyHostnameKey.Value(ctx)).
 				Msgf("update not sent, context cancelled")
-			notifierUpdateSent.WithLabelValues("cancelled", update.Type.String()).Inc()
+			notifierUpdateSent.WithLabelValues("cancelled", update.Type.String(), types.NotifyOriginKey.Value(ctx)).Inc()
 
 			return
 		case c <- update:
@@ -151,11 +154,23 @@ func (n *Notifier) NotifyByNodeID(
 				Any("origin", ctx.Value("origin")).
 				Any("origin-hostname", ctx.Value("hostname")).
 				Msgf("update successfully sent on chan")
-			notifierUpdateSent.WithLabelValues("ok", update.Type.String()).Inc()
+			notifierUpdateSent.WithLabelValues("ok", update.Type.String(), types.NotifyOriginKey.Value(ctx)).Inc()
 		}
 	}
 }
 
+func (n *Notifier) sendAll(update types.StateUpdate) {
+	start := time.Now()
+	n.l.RLock()
+	defer n.l.RUnlock()
+	notifierWaitForLock.WithLabelValues("send-all").Observe(time.Since(start).Seconds())
+
+	for _, c := range n.nodes {
+		c <- update
+		notifierUpdateSent.WithLabelValues("ok", update.Type.String(), "send-all").Inc()
+	}
+}
+
 func (n *Notifier) String() string {
 	n.l.RLock()
 	defer n.l.RUnlock()
@@ -177,3 +192,166 @@ func (n *Notifier) String() string {
 
 	return b.String()
 }
+
+type batcher struct {
+	tick *time.Ticker
+
+	mu sync.Mutex
+
+	cancelCh chan struct{}
+
+	changedNodeIDs set.Slice[types.NodeID]
+	nodesChanged   bool
+	patches        map[types.NodeID]tailcfg.PeerChange
+	patchesChanged bool
+
+	n *Notifier
+}
+
+func newBatcher(batchTime time.Duration, n *Notifier) *batcher {
+	return &batcher{
+		tick:     time.NewTicker(batchTime),
+		cancelCh: make(chan struct{}),
+		patches:  make(map[types.NodeID]tailcfg.PeerChange),
+		n:        n,
+	}
+
+}
+
+func (b *batcher) close() {
+	b.cancelCh <- struct{}{}
+}
+
+// addOrPassthrough adds the update to the batcher, if it is not a
+// type that is currently batched, it will be sent immediately.
+func (b *batcher) addOrPassthrough(update types.StateUpdate) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	switch update.Type {
+	case types.StatePeerChanged:
+		b.changedNodeIDs.Add(update.ChangeNodes...)
+		b.nodesChanged = true
+
+	case types.StatePeerChangedPatch:
+		for _, newPatch := range update.ChangePatches {
+			if curr, ok := b.patches[types.NodeID(newPatch.NodeID)]; ok {
+				overwritePatch(&curr, newPatch)
+				b.patches[types.NodeID(newPatch.NodeID)] = curr
+			} else {
+				b.patches[types.NodeID(newPatch.NodeID)] = *newPatch
+			}
+		}
+		b.patchesChanged = true
+
+	default:
+		b.n.sendAll(update)
+	}
+}
+
+// flush sends all the accumulated patches to all
+// nodes in the notifier.
+func (b *batcher) flush() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.nodesChanged || b.patchesChanged {
+		var patches []*tailcfg.PeerChange
+		// If a node is getting a full update from a change
+		// node update, then the patch can be dropped.
+		for nodeID, patch := range b.patches {
+			if b.changedNodeIDs.Contains(nodeID) {
+				delete(b.patches, nodeID)
+			} else {
+				patches = append(patches, &patch)
+			}
+		}
+
+		changedNodes := b.changedNodeIDs.Slice().AsSlice()
+		sort.Slice(changedNodes, func(i, j int) bool {
+			return changedNodes[i] < changedNodes[j]
+		})
+
+		if b.changedNodeIDs.Slice().Len() > 0 {
+			update := types.StateUpdate{
+				Type:        types.StatePeerChanged,
+				ChangeNodes: changedNodes,
+			}
+
+			b.n.sendAll(update)
+		}
+
+		if len(patches) > 0 {
+			patchUpdate := types.StateUpdate{
+				Type:          types.StatePeerChangedPatch,
+				ChangePatches: patches,
+			}
+
+			b.n.sendAll(patchUpdate)
+		}
+
+		b.changedNodeIDs = set.Slice[types.NodeID]{}
+		b.nodesChanged = false
+		b.patches = make(map[types.NodeID]tailcfg.PeerChange, len(b.patches))
+		b.patchesChanged = false
+	}
+}
+
+func (b *batcher) doWork() {
+	for {
+		select {
+		case <-b.cancelCh:
+			return
+		case <-b.tick.C:
+			b.flush()
+		}
+	}
+}
+
+// overwritePatch takes the current patch and a newer patch
+// and override any field that has changed
+func overwritePatch(currPatch, newPatch *tailcfg.PeerChange) {
+	if newPatch.DERPRegion != 0 {
+		currPatch.DERPRegion = newPatch.DERPRegion
+	}
+
+	if newPatch.Cap != 0 {
+		currPatch.Cap = newPatch.Cap
+	}
+
+	if newPatch.CapMap != nil {
+		currPatch.CapMap = newPatch.CapMap
+	}
+
+	if newPatch.Endpoints != nil {
+		currPatch.Endpoints = newPatch.Endpoints
+	}
+
+	if newPatch.Key != nil {
+		currPatch.Key = newPatch.Key
+	}
+
+	if newPatch.KeySignature != nil {
+		currPatch.KeySignature = newPatch.KeySignature
+	}
+
+	if newPatch.DiscoKey != nil {
+		currPatch.DiscoKey = newPatch.DiscoKey
+	}
+
+	if newPatch.Online != nil {
+		currPatch.Online = newPatch.Online
+	}
+
+	if newPatch.LastSeen != nil {
+		currPatch.LastSeen = newPatch.LastSeen
+	}
+
+	if newPatch.KeyExpiry != nil {
+		currPatch.KeyExpiry = newPatch.KeyExpiry
+	}
+
+	if newPatch.Capabilities != nil {
+		currPatch.Capabilities = newPatch.Capabilities
+	}
+}

hscontrol/notifier/notifier_test.go

@@ -0,0 +1,249 @@
+package notifier
+
+import (
+	"context"
+	"net/netip"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/juanfont/headscale/hscontrol/types"
+	"github.com/juanfont/headscale/hscontrol/util"
+	"tailscale.com/tailcfg"
+)
+
+func TestBatcher(t *testing.T) {
+	tests := []struct {
+		name    string
+		updates []types.StateUpdate
+		want    []types.StateUpdate
+	}{
+		{
+			name: "full-passthrough",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StateFullUpdate,
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StateFullUpdate,
+				},
+			},
+		},
+		{
+			name: "derp-passthrough",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StateDERPUpdated,
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StateDERPUpdated,
+				},
+			},
+		},
+		{
+			name: "single-node-update",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StatePeerChanged,
+					ChangeNodes: []types.NodeID{
+						2,
+					},
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StatePeerChanged,
+					ChangeNodes: []types.NodeID{
+						2,
+					},
+				},
+			},
+		},
+		{
+			name: "merge-node-update",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StatePeerChanged,
+					ChangeNodes: []types.NodeID{
+						2, 4,
+					},
+				},
+				{
+					Type: types.StatePeerChanged,
+					ChangeNodes: []types.NodeID{
+						2, 3,
+					},
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StatePeerChanged,
+					ChangeNodes: []types.NodeID{
+						2, 3, 4,
+					},
+				},
+			},
+		},
+		{
+			name: "single-patch-update",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID:     2,
+							DERPRegion: 5,
+						},
+					},
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID:     2,
+							DERPRegion: 5,
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "merge-patch-to-same-node-update",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID:     2,
+							DERPRegion: 5,
+						},
+					},
+				},
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID:     2,
+							DERPRegion: 6,
+						},
+					},
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID:     2,
+							DERPRegion: 6,
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "merge-patch-to-multiple-node-update",
+			updates: []types.StateUpdate{
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID: 3,
+							Endpoints: []netip.AddrPort{
+								netip.MustParseAddrPort("1.1.1.1:9090"),
+							},
+						},
+					},
+				},
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID: 3,
+							Endpoints: []netip.AddrPort{
+								netip.MustParseAddrPort("1.1.1.1:9090"),
+								netip.MustParseAddrPort("2.2.2.2:8080"),
+							},
+						},
+					},
+				},
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID:     4,
+							DERPRegion: 6,
+						},
+					},
+				},
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID: 4,
+							Cap:    tailcfg.CapabilityVersion(54),
+						},
+					},
+				},
+			},
+			want: []types.StateUpdate{
+				{
+					Type: types.StatePeerChangedPatch,
+					ChangePatches: []*tailcfg.PeerChange{
+						{
+							NodeID: 3,
+							Endpoints: []netip.AddrPort{
+								netip.MustParseAddrPort("1.1.1.1:9090"),
+								netip.MustParseAddrPort("2.2.2.2:8080"),
+							},
+						},
+						{
+							NodeID:     4,
+							DERPRegion: 6,
+							Cap:        tailcfg.CapabilityVersion(54),
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			n := NewNotifier(&types.Config{
+				Tuning: types.Tuning{
+					// We will call flush manually for the tests,
+					// so do not run the worker.
+					BatchChangeDelay: time.Hour,
+				},
+			})
+
+			ch := make(chan types.StateUpdate, 30)
+			defer close(ch)
+			n.AddNode(1, ch)
+			defer n.RemoveNode(1)
+
+			for _, u := range tt.updates {
+				n.NotifyAll(context.Background(), u)
+			}
+
+			n.b.flush()
+
+			var got []types.StateUpdate
+			for len(ch) > 0 {
+				out := <-ch
+				got = append(got, out)
+			}
+
+			if diff := cmp.Diff(tt.want, got, util.Comparers...); diff != "" {
+				t.Errorf("batcher() unexpected result (-want +got):\n%s", diff)
+			}
+		})
+	}
+}

hscontrol/poll.go

@@ -66,10 +66,16 @@ func (h *Headscale) newMapSession(
 ) *mapSession {
 	warnf, infof, tracef, errf := logPollFunc(req, node)
 
-	// Use a buffered channel in case a node is not fully ready
-	// to receive a message to make sure we dont block the entire
-	// notifier.
-	updateChan := make(chan types.StateUpdate, h.cfg.Tuning.NodeMapSessionBufferedChanSize)
+	var updateChan chan types.StateUpdate
+	if req.Stream {
+		// Use a buffered channel in case a node is not fully ready
+		// to receive a message to make sure we dont block the entire
+		// notifier.
+		updateChan = make(chan types.StateUpdate, h.cfg.Tuning.NodeMapSessionBufferedChanSize)
+		updateChan <- types.StateUpdate{
+			Type: types.StateFullUpdate,
+		}
+	}
 
 	return &mapSession{
 		h:      h,
@@ -218,33 +224,26 @@ func (m *mapSession) serve() {
 	ctx, cancel := context.WithCancel(context.WithValue(m.ctx, nodeNameContextKey, m.node.Hostname))
 	defer cancel()
 
-	// TODO(kradalby): Make this available through a tuning envvar
-	wait := time.Second
-
-	// Add a circuit breaker, if the loop is not interrupted
-	// inbetween listening for the channels, some updates
-	// might get stale and stucked in the "changed" map
-	// defined below.
-	blockBreaker := time.NewTicker(wait)
-
-	// true means changed, false means removed
-	var changed map[types.NodeID]bool
-	var patches []*tailcfg.PeerChange
-	var derp bool
-
-	// Set full to true to immediatly send a full mapresponse
-	full := true
-	prev := time.Now()
-	lastMessage := ""
-
 	// Loop through updates and continuously send them to the
 	// client.
 	for {
-		// If a full update has been requested or there are patches, then send it immediately
-		// otherwise wait for the "batching" of changes or patches
-		if full || patches != nil || (changed != nil && time.Since(prev) > wait) {
+		// consume channels with update, keep alives or "batch" blocking signals
+		select {
+		case <-m.cancelCh:
+			m.tracef("poll cancelled received")
+			return
+		case <-ctx.Done():
+			m.tracef("poll context done")
+			return
+
+		// Consume all updates sent to node
+		case update := <-m.ch:
+			m.tracef("received stream update: %s %s", update.Type.String(), update.Message)
+			mapResponseUpdateReceived.WithLabelValues(update.Type.String()).Inc()
+
 			var data []byte
 			var err error
+			var lastMessage string
 
 			// Ensure the node object is updated, for example, there
 			// might have been a hostinfo update in a sidechannel
@@ -256,62 +255,43 @@ func (m *mapSession) serve() {
 				return
 			}
 
-			// If there are patches _and_ fully changed nodes, filter the
-			// patches and remove all patches that are present for the full
-			// changes updates. This allows us to send them as part of the
-			// PeerChange update, but only for nodes that are not fully changed.
-			// The fully changed nodes will be updated from the database and
-			// have all the updates needed.
-			// This means that the patches left are for nodes that has no
-			// updates that requires a full update.
-			// Patches are not suppose to be mixed in, but can be.
-			//
-			// From tailcfg docs:
-			// These are applied after Peers* above, but in practice the
-			// control server should only send these on their own, without
-			//
-			// Currently, there is no effort to merge patch updates, they
-			// are all sent, and the client will apply them in order.
-			// TODO(kradalby): Merge Patches for the same IDs to send less
-			// data and give the client less work.
-			if patches != nil && changed != nil {
-				var filteredPatches []*tailcfg.PeerChange
-
-				for _, patch := range patches {
-					if _, ok := changed[types.NodeID(patch.NodeID)]; !ok {
-						filteredPatches = append(filteredPatches, patch)
-					}
-				}
-
-				patches = filteredPatches
-			}
-
 			updateType := "full"
-			// When deciding what update to send, the following is considered,
-			// Full is a superset of all updates, when a full update is requested,
-			// send only that and move on, all other updates will be present in
-			// a full map response.
-			//
-			// If a map of changed nodes exists, prefer sending that as it will
-			// contain all the updates for the node, including patches, as it
-			// is fetched freshly from the database when building the response.
-			//
-			// If there is full changes registered, but we have patches for individual
-			// nodes, send them.
-			//
-			// Finally, if a DERP map is the only request, send that alone.
-			if full {
+			switch update.Type {
+			case types.StateFullUpdate:
 				m.tracef("Sending Full MapResponse")
 				data, err = m.mapper.FullMapResponse(m.req, m.node, m.h.ACLPolicy, fmt.Sprintf("from mapSession: %p, stream: %t", m, m.isStreaming()))
-			} else if changed != nil {
+			case types.StatePeerChanged:
+				changed := make(map[types.NodeID]bool, len(update.ChangeNodes))
+
+				for _, nodeID := range update.ChangeNodes {
+					changed[nodeID] = true
+				}
+
+				lastMessage = update.Message
 				m.tracef(fmt.Sprintf("Sending Changed MapResponse: %v", lastMessage))
-				data, err = m.mapper.PeerChangedResponse(m.req, m.node, changed, patches, m.h.ACLPolicy, lastMessage)
+				data, err = m.mapper.PeerChangedResponse(m.req, m.node, changed, update.ChangePatches, m.h.ACLPolicy, lastMessage)
 				updateType = "change"
-			} else if patches != nil {
+
+			case types.StatePeerChangedPatch:
 				m.tracef(fmt.Sprintf("Sending Changed Patch MapResponse: %v", lastMessage))
-				data, err = m.mapper.PeerChangedPatchResponse(m.req, m.node, patches, m.h.ACLPolicy)
+				data, err = m.mapper.PeerChangedPatchResponse(m.req, m.node, update.ChangePatches, m.h.ACLPolicy)
 				updateType = "patch"
-			} else if derp {
+			case types.StatePeerRemoved:
+				changed := make(map[types.NodeID]bool, len(update.Removed))
+
+				for _, nodeID := range update.Removed {
+					changed[nodeID] = false
+				}
+				m.tracef(fmt.Sprintf("Sending Changed MapResponse: %v", lastMessage))
+				data, err = m.mapper.PeerChangedResponse(m.req, m.node, changed, update.ChangePatches, m.h.ACLPolicy, lastMessage)
+				updateType = "remove"
+			case types.StateSelfUpdate:
+				lastMessage = update.Message
+				m.tracef(fmt.Sprintf("Sending Changed MapResponse: %v", lastMessage))
+				// create the map so an empty (self) update is sent
+				data, err = m.mapper.PeerChangedResponse(m.req, m.node, make(map[types.NodeID]bool), update.ChangePatches, m.h.ACLPolicy, lastMessage)
+				updateType = "remove"
+			case types.StateDERPUpdated:
 				m.tracef("Sending DERPUpdate MapResponse")
 				data, err = m.mapper.DERPMapResponse(m.req, m.node, m.h.DERPMap)
 				updateType = "derp"
@@ -348,68 +328,6 @@ func (m *mapSession) serve() {
 				m.tracef("update sent")
 			}
 
-			// reset
-			changed = nil
-			patches = nil
-			lastMessage = ""
-			full = false
-			derp = false
-			prev = time.Now()
-		}
-
-		// consume channels with update, keep alives or "batch" blocking signals
-		select {
-		case <-m.cancelCh:
-			m.tracef("poll cancelled received")
-			return
-		case <-ctx.Done():
-			m.tracef("poll context done")
-			return
-
-			// Avoid infinite block that would potentially leave
-		// some updates in the changed map.
-		case <-blockBreaker.C:
-			continue
-
-		// Consume all updates sent to node
-		case update := <-m.ch:
-			m.tracef("received stream update: %s %s", update.Type.String(), update.Message)
-			mapResponseUpdateReceived.WithLabelValues(update.Type.String()).Inc()
-
-			switch update.Type {
-			case types.StateFullUpdate:
-				full = true
-			case types.StatePeerChanged:
-				if changed == nil {
-					changed = make(map[types.NodeID]bool)
-				}
-
-				for _, nodeID := range update.ChangeNodes {
-					changed[nodeID] = true
-				}
-
-				lastMessage = update.Message
-			case types.StatePeerChangedPatch:
-				patches = append(patches, update.ChangePatches...)
-			case types.StatePeerRemoved:
-				if changed == nil {
-					changed = make(map[types.NodeID]bool)
-				}
-
-				for _, nodeID := range update.Removed {
-					changed[nodeID] = false
-				}
-			case types.StateSelfUpdate:
-				// create the map so an empty (self) update is sent
-				if changed == nil {
-					changed = make(map[types.NodeID]bool)
-				}
-
-				lastMessage = update.Message
-			case types.StateDERPUpdated:
-				derp = true
-			}
-
 		case <-m.keepAliveTicker.C:
 			data, err := m.mapper.KeepAliveResponse(m.req, m.node)
 			if err != nil {

hscontrol/types/common.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"tailscale.com/tailcfg"
+	"tailscale.com/util/ctxkey"
 )
 
 const (
@@ -183,10 +184,14 @@ func StateUpdateExpire(nodeID NodeID, expiry time.Time) StateUpdate {
 	}
 }
 
+var (
+	NotifyOriginKey   = ctxkey.New("notify.origin", "")
+	NotifyHostnameKey = ctxkey.New("notify.hostname", "")
+)
+
 func NotifyCtx(ctx context.Context, origin, hostname string) context.Context {
-	ctx2, _ := context.WithTimeout(
-		context.WithValue(context.WithValue(ctx, "hostname", hostname), "origin", origin),
-		3*time.Second,
-	)
+	ctx2, _ := context.WithTimeout(ctx, 3*time.Second)
+	ctx2 = NotifyOriginKey.WithValue(ctx2, origin)
+	ctx2 = NotifyHostnameKey.WithValue(ctx2, hostname)
 	return ctx2
 }

integration/hsic/hsic.go

@@ -11,6 +11,7 @@ import (
 	"encoding/pem"
 	"errors"
 	"fmt"
+	"io"
 	"log"
 	"math/big"
 	"net"
@@ -396,6 +397,14 @@ func (t *HeadscaleInContainer) Shutdown() error {
 		)
 	}
 
+	err = t.SaveMetrics("/tmp/control/metrics.txt")
+	if err != nil {
+		log.Printf(
+			"Failed to metrics from control: %s",
+			err,
+		)
+	}
+
 	// Send a interrupt signal to the "headscale" process inside the container
 	// allowing it to shut down gracefully and flush the profile to disk.
 	// The container will live for a bit longer due to the sleep at the end.
@@ -448,6 +457,25 @@ func (t *HeadscaleInContainer) SaveLog(path string) error {
 	return dockertestutil.SaveLog(t.pool, t.container, path)
 }
 
+func (t *HeadscaleInContainer) SaveMetrics(savePath string) error {
+	resp, err := http.Get(fmt.Sprintf("http://%s:9090/metrics", t.hostname))
+	if err != nil {
+		return fmt.Errorf("getting metrics: %w", err)
+	}
+	defer resp.Body.Close()
+	out, err := os.Create(savePath)
+	if err != nil {
+		return fmt.Errorf("creating file for metrics: %w", err)
+	}
+	defer out.Close()
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		return fmt.Errorf("copy response to file: %w", err)
+	}
+
+	return nil
+}
+
 func (t *HeadscaleInContainer) SaveProfile(savePath string) error {
 	tarFile, err := t.FetchPath("/tmp/profile")
 	if err != nil {

integration/route_test.go

@@ -252,7 +252,7 @@ func TestHASubnetRouterFailover(t *testing.T) {
 
 	scenario, err := NewScenario(dockertestMaxWait())
 	assertNoErrf(t, "failed to create scenario: %s", err)
-	// defer scenario.Shutdown()
+	defer scenario.Shutdown()
 
 	spec := map[string]int{
 		user: 3,