Create a Tracker when starting the router

The tracker's HandleUpdate method is called by the ring update routines.

In addition, we add a dummy overlay for AWSVPC to make `weave (status|
report)` to produce reasonable reports which includes AWS hosts
connection state.

ipam/allocator.go

@@ -14,6 +14,7 @@ import (
 	"github.com/weaveworks/weave/ipam/paxos"
 	"github.com/weaveworks/weave/ipam/ring"
 	"github.com/weaveworks/weave/ipam/space"
+	"github.com/weaveworks/weave/ipam/tracker"
 	"github.com/weaveworks/weave/net/address"
 )
 
@@ -85,11 +86,14 @@ type Config struct {
 	Quorum      func() uint
 	Db          db.DB
 	IsKnownPeer func(name mesh.PeerName) bool
+	Tracker     tracker.LocalRangeTracker
 }
 
 // NewAllocator creates and initialises a new Allocator
 func NewAllocator(config Config) *Allocator {
 	var participant paxos.Participant
+	var alloc *Allocator
+	var onUpdate ring.OnUpdate
 
 	if config.IsObserver {
 		participant = paxos.NewObserver()
@@ -97,11 +101,19 @@ func NewAllocator(config Config) *Allocator {
 		participant = paxos.NewNode(config.OurName, config.OurUID, 0)
 	}
 
-	return &Allocator{
+	if config.Tracker != nil {
+		onUpdate = func(prev []address.Range, curr []address.Range, local bool) {
+			if err := config.Tracker.HandleUpdate(prev, curr, local); err != nil {
+				alloc.errorf("HandleUpdate failed: %s", err)
+			}
+		}
+	}
+
+	alloc = &Allocator{
 		ourName:     config.OurName,
 		seed:        config.Seed,
 		universe:    config.Universe,
-		ring:        ring.New(config.Universe.Range().Start, config.Universe.Range().End, config.OurName),
+		ring:        ring.New(config.Universe.Range().Start, config.Universe.Range().End, config.OurName, onUpdate),
 		owned:       make(map[string]ownedData),
 		db:          config.Db,
 		paxos:       participant,
@@ -111,6 +123,7 @@ func NewAllocator(config Config) *Allocator {
 		dead:        make(map[string]time.Time),
 		now:         time.Now,
 	}
+	return alloc
 }
 
 func ParseCIDRSubnet(cidrStr string) (cidr address.CIDR, err error) {
@@ -958,7 +971,7 @@ func (alloc *Allocator) loadPersistedData() bool {
 		return false
 	}
 
-	alloc.ring = persistedRing
+	alloc.ring.Restore(persistedRing)
 	alloc.space.UpdateRanges(alloc.ring.OwnedRanges())
 
 	if ownedFound {
@@ -1068,6 +1081,9 @@ func (alloc *Allocator) fatalf(fmt string, args ...interface{}) {
 func (alloc *Allocator) warnf(fmt string, args ...interface{}) {
 	alloc.logf(common.Log.Warnf, fmt, args...)
 }
+func (alloc *Allocator) errorf(fmt string, args ...interface{}) {
+	common.Log.Errorf("[allocator %s] "+fmt, append([]interface{}{alloc.ourName}, args...)...)
+}
 func (alloc *Allocator) infof(fmt string, args ...interface{}) {
 	alloc.logf(common.Log.Infof, fmt, args...)
 }

ipam/ring/ring.go

@@ -18,12 +18,15 @@ import (
 	"github.com/weaveworks/weave/net/address"
 )
 
+type OnUpdate func(prev, curr []address.Range, local bool)
+
 // Ring represents the ring itself
 type Ring struct {
 	Start, End address.Address // [min, max) tokens in this ring.  Due to wrapping, min == max (effectively)
 	Peer       mesh.PeerName   // name of peer owning this ring instance
 	Entries    entries         // list of entries sorted by token
 	Seeds      []mesh.PeerName // peers with which the ring was seeded
+	onUpdate   OnUpdate
 }
 
 func (r *Ring) assertInvariants() {
@@ -94,15 +97,33 @@ func (r *Ring) checkEntries(entries entries) error {
 	return nil
 }
 
+func (r *Ring) trackUpdates() func() {
+	return r.trackUpdatesOfPeer(r.Peer)
+}
+
+func (r *Ring) trackUpdatesOfPeer(peer mesh.PeerName) func() {
+	if r.onUpdate == nil {
+		return func() {}
+	}
+	ranges := r.OwnedRangesOfPeer(peer)
+	return func() { r.onUpdate(ranges, r.OwnedRangesOfPeer(peer), peer == r.Peer) }
+}
+
 // New creates an empty ring belonging to peer.
-func New(start, end address.Address, peer mesh.PeerName) *Ring {
+func New(start, end address.Address, peer mesh.PeerName, f OnUpdate) *Ring {
 	common.Assert(start < end)
 
-	ring := &Ring{Start: start, End: end, Peer: peer, Entries: make([]*entry, 0)}
+	ring := &Ring{Start: start, End: end, Peer: peer, Entries: make([]*entry, 0), onUpdate: f}
 	ring.updateExportedVariables()
 	return ring
 }
 
+func (r *Ring) Restore(other *Ring) {
+	onUpdate := r.onUpdate
+	*r = *other
+	r.onUpdate = onUpdate
+}
+
 func (r *Ring) Range() address.Range {
 	return address.Range{Start: r.Start, End: r.End}
 }
@@ -126,6 +147,7 @@ func (r *Ring) GrantRangeToHost(start, end address.Address, peer mesh.PeerName)
 	//fmt.Printf("%s GrantRangeToHost [%v,%v) -> %s\n", r.Peer, start, end, peer)
 
 	r.assertInvariants()
+	defer r.trackUpdates()()
 	defer r.assertInvariants()
 	defer r.updateExportedVariables()
 
@@ -193,6 +215,7 @@ func (r *Ring) GrantRangeToHost(start, end address.Address, peer mesh.PeerName)
 // got updated as a result.
 func (r *Ring) Merge(gossip Ring) (bool, error) {
 	r.assertInvariants()
+	defer r.trackUpdates()()
 	defer r.updateExportedVariables()
 
 	// Don't panic when checking the gossiped in ring.
@@ -230,6 +253,7 @@ func (r *Ring) Merge(gossip Ring) (bool, error) {
 		r.Seeds = gossip.Seeds
 	}
 	r.Entries = result
+
 	return updated, nil
 }
 
@@ -336,10 +360,14 @@ func (r *Ring) splitRangesOverZero(ranges []address.Range) []address.Range {
 // ranges are owned by this peer.  Will split ranges which
 // span 0 in the ring.
 func (r *Ring) OwnedRanges() (result []address.Range) {
+	return r.OwnedRangesOfPeer(r.Peer)
+}
+
+func (r *Ring) OwnedRangesOfPeer(peer mesh.PeerName) (result []address.Range) {
 	r.assertInvariants()
 
 	for i, entry := range r.Entries {
-		if entry.Peer == r.Peer {
+		if entry.Peer == peer {
 			nextEntry := r.Entries.entry(i + 1)
 			result = append(result, address.Range{Start: entry.Token, End: nextEntry.Token})
 		}
@@ -371,6 +399,8 @@ func (r *Ring) AllRangeInfo() (result []RangeInfo) {
 // in.  Only works for empty rings. Each claimed range is CIDR-aligned.
 func (r *Ring) ClaimForPeers(peers []mesh.PeerName) {
 	common.Assert(r.Empty())
+
+	defer r.trackUpdates()()
 	defer r.assertInvariants()
 	defer r.updateExportedVariables()
 	defer func() {
@@ -527,6 +557,8 @@ func (r *Ring) PickPeerForTransfer(isValid func(mesh.PeerName) bool) mesh.PeerNa
 // and return ranges indicating the new space we picked up
 func (r *Ring) Transfer(from, to mesh.PeerName) []address.Range {
 	r.assertInvariants()
+	defer r.trackUpdates()()
+	defer r.trackUpdatesOfPeer(from)()
 	defer r.assertInvariants()
 	defer r.updateExportedVariables()
 

ipam/ring/ring_test.go

@@ -36,8 +36,12 @@ func merge(r1, r2 *Ring) error {
 	return err
 }
 
+func NewRing(start, end address.Address, peer mesh.PeerName) *Ring {
+	return New(start, end, peer, nil)
+}
+
 func TestInvariants(t *testing.T) {
-	ring := New(start, end, peer1name)
+	ring := NewRing(start, end, peer1name)
 
 	// Check ring is sorted
 	ring.Entries = []*entry{{Token: dot245, Peer: peer1name}, {Token: dot10, Peer: peer2name}}
@@ -48,7 +52,7 @@ func TestInvariants(t *testing.T) {
 	require.True(t, ring.checkInvariants() == ErrTokenRepeated, "Expected error")
 
 	// Check tokens are in bounds
-	ring = New(dot10, dot245, peer1name)
+	ring = NewRing(dot10, dot245, peer1name)
 	ring.Entries = []*entry{{Token: start, Peer: peer1name}}
 	require.True(t, ring.checkInvariants() == ErrTokenOutOfRange, "Expected error")
 
@@ -57,7 +61,7 @@ func TestInvariants(t *testing.T) {
 }
 
 func TestInsert(t *testing.T) {
-	ring := New(start, end, peer1name)
+	ring := NewRing(start, end, peer1name)
 	ring.Entries = []*entry{{Token: start, Peer: peer1name, Free: 255}}
 
 	require.Panics(t, func() {
@@ -82,7 +86,7 @@ func TestInsert(t *testing.T) {
 }
 
 func TestBetween(t *testing.T) {
-	ring1 := New(start, end, peer1name)
+	ring1 := NewRing(start, end, peer1name)
 	ring1.Entries = []*entry{{Token: start, Peer: peer1name, Free: 255}}
 
 	// First off, in a ring where everything is owned by the peer
@@ -124,8 +128,8 @@ func TestBetween(t *testing.T) {
 }
 
 func TestGrantSimple(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	// Claim everything for peer1
 	ring1.ClaimItAll()
@@ -159,8 +163,8 @@ func TestGrantSimple(t *testing.T) {
 }
 
 func TestGrantSplit(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	// Claim everything for peer1
 	ring1.Entries = []*entry{{Token: start, Peer: peer1name, Free: 256}}
@@ -188,8 +192,8 @@ func TestGrantSplit(t *testing.T) {
 }
 
 func TestMergeSimple(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	// Claim everything for peer1
 	ring1.ClaimItAll()
@@ -217,18 +221,18 @@ func TestMergeSimple(t *testing.T) {
 
 func TestMergeErrors(t *testing.T) {
 	// Cannot Merge in an invalid ring
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 	ring2.Entries = []*entry{{Token: middle, Peer: peer2name}, {Token: start, Peer: peer2name}}
 	require.True(t, merge(ring1, ring2) == ErrNotSorted, "Expected ErrNotSorted")
 
 	// Should Merge two rings for different ranges
-	ring2 = New(start, middle, peer2name)
+	ring2 = NewRing(start, middle, peer2name)
 	ring2.Entries = []*entry{}
 	require.True(t, merge(ring1, ring2) == ErrDifferentRange, "Expected ErrDifferentRange")
 
 	// Cannot Merge newer version of entry I own
-	ring2 = New(start, end, peer2name)
+	ring2 = NewRing(start, end, peer2name)
 	ring1.Entries = []*entry{{Token: start, Peer: peer1name}}
 	ring2.Entries = []*entry{{Token: start, Peer: peer1name, Version: 1}}
 	fmt.Println(merge(ring1, ring2))
@@ -246,8 +250,8 @@ func TestMergeErrors(t *testing.T) {
 }
 
 func TestMergeMore(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	assertRing := func(ring *Ring, entries entries) {
 		require.Equal(t, entries, ring.Entries)
@@ -297,8 +301,8 @@ func TestMergeMore(t *testing.T) {
 }
 
 func TestMergeSplit(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	// Claim everything for peer2
 	ring1.Entries = []*entry{{Token: start, Peer: peer2name, Free: 256}}
@@ -320,8 +324,8 @@ func TestMergeSplit(t *testing.T) {
 }
 
 func TestMergeSplit2(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	// Claim everything for peer2
 	ring1.Entries = []*entry{{Token: start, Peer: peer2name, Free: 250}, {Token: dot250, Peer: peer2name, Free: 5}}
@@ -344,8 +348,8 @@ func TestMergeSplit2(t *testing.T) {
 
 // A simple test, very similar to above, but using the marshalling to byte[]s
 func TestGossip(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	assertRing := func(ring *Ring, entries entries) {
 		require.Equal(t, entries, ring.Entries)
@@ -372,7 +376,7 @@ func assertPeersWithSpace(t *testing.T, ring *Ring, start, end address.Address,
 }
 
 func TestFindFree(t *testing.T) {
-	ring1 := New(start, end, peer1name)
+	ring1 := NewRing(start, end, peer1name)
 
 	assertPeersWithSpace(t, ring1, start, end, 0)
 
@@ -408,8 +412,8 @@ func TestFindFree(t *testing.T) {
 }
 
 func TestReportFree(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	ring1.ClaimItAll()
 	ring1.GrantRangeToHost(middle, end, peer2name)
@@ -423,7 +427,7 @@ func TestReportFree(t *testing.T) {
 }
 
 func TestMisc(t *testing.T) {
-	ring := New(start, end, peer1name)
+	ring := NewRing(start, end, peer1name)
 
 	require.True(t, ring.Empty(), "empty")
 
@@ -432,8 +436,8 @@ func TestMisc(t *testing.T) {
 }
 
 func TestEmptyGossip(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	ring1.ClaimItAll()
 	// This used to panic, and it shouldn't
@@ -441,8 +445,8 @@ func TestEmptyGossip(t *testing.T) {
 }
 
 func TestMergeOldMessage(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	ring1.ClaimItAll()
 	require.NoError(t, merge(ring2, ring1))
@@ -452,8 +456,8 @@ func TestMergeOldMessage(t *testing.T) {
 }
 
 func TestSplitRangeAtBeginning(t *testing.T) {
-	ring1 := New(start, end, peer1name)
-	ring2 := New(start, end, peer2name)
+	ring1 := NewRing(start, end, peer1name)
+	ring2 := NewRing(start, end, peer2name)
 
 	ring1.ClaimItAll()
 	require.NoError(t, merge(ring2, ring1))
@@ -463,7 +467,7 @@ func TestSplitRangeAtBeginning(t *testing.T) {
 }
 
 func TestOwnedRange(t *testing.T) {
-	ring1 := New(start, end, peer1name)
+	ring1 := NewRing(start, end, peer1name)
 	ring1.ClaimItAll()
 
 	require.Equal(t, []address.Range{{Start: start, End: end}}, ring1.OwnedRanges())
@@ -471,7 +475,7 @@ func TestOwnedRange(t *testing.T) {
 	ring1.GrantRangeToHost(middle, end, peer2name)
 	require.Equal(t, []address.Range{{Start: start, End: middle}}, ring1.OwnedRanges())
 
-	ring2 := New(start, end, peer2name)
+	ring2 := NewRing(start, end, peer2name)
 	merge(ring2, ring1)
 	require.Equal(t, []address.Range{{Start: middle, End: end}}, ring2.OwnedRanges())
 
@@ -486,7 +490,7 @@ func TestOwnedRange(t *testing.T) {
 
 func TestTransfer(t *testing.T) {
 	// First test just checks if we can grant some range to a host, when we transfer it, we get it back
-	ring1 := New(start, end, peer1name)
+	ring1 := NewRing(start, end, peer1name)
 	ring1.ClaimItAll()
 	ring1.GrantRangeToHost(middle, end, peer2name)
 	ring1.Transfer(peer2name, peer1name)
@@ -494,7 +498,7 @@ func TestTransfer(t *testing.T) {
 
 	// Second test is what happens when a token exists at the end of a range but is transferred
 	// - does it get resurrected correctly?
-	ring1 = New(start, end, peer1name)
+	ring1 = NewRing(start, end, peer1name)
 	ring1.ClaimItAll()
 	ring1.GrantRangeToHost(middle, end, peer2name)
 	ring1.Transfer(peer2name, peer1name)
@@ -503,7 +507,7 @@ func TestTransfer(t *testing.T) {
 }
 
 func TestOwner(t *testing.T) {
-	ring1 := New(start, end, peer1name)
+	ring1 := NewRing(start, end, peer1name)
 	require.True(t, ring1.Contains(start), "start should be in ring")
 	require.False(t, ring1.Contains(end), "end should not be in ring")
 
@@ -544,7 +548,7 @@ func TestClaimForPeers(t *testing.T) {
 	peers := makePeers(numPeers)
 	// Test for a range of peer counts
 	for i := 0; i < numPeers; i++ {
-		ring := New(start, end, peers[0])
+		ring := NewRing(start, end, peers[0])
 		ring.ClaimForPeers(peers[:i+1])
 	}
 }
@@ -582,7 +586,7 @@ func TestFuzzRing(t *testing.T) {
 		sort.Sort(addressSlice(tokens))
 
 		peer := peers[rand.Intn(len(peers))]
-		ring := New(start, end, peer)
+		ring := NewRing(start, end, peer)
 		for _, token := range tokens {
 			peer = peers[rand.Intn(len(peers))]
 			ring.Entries = append(ring.Entries, &entry{Token: start + token, Peer: peer})
@@ -616,7 +620,7 @@ func TestFuzzRing(t *testing.T) {
 		}
 
 		peer := peers[rand.Intn(len(peers))]
-		ring := New(start, end, peer)
+		ring := NewRing(start, end, peer)
 		for _, token := range tokens {
 			peer = peers[rand.Intn(len(peers))]
 			ring.Entries = append(ring.Entries, &entry{Token: start + token, Peer: peer})
@@ -654,7 +658,7 @@ func TestFuzzRingHard(t *testing.T) {
 		common.Log.Debugf("%s: Adding peer", peer)
 		nextPeerID++
 		peers = append(peers, peer)
-		rings = append(rings, New(start, end, peer))
+		rings = append(rings, NewRing(start, end, peer))
 	}
 
 	for i := 0; i < numPeers; i++ {

prog/weaver/main.go

@@ -22,6 +22,7 @@ import (
 	"github.com/weaveworks/weave/common/docker"
 	"github.com/weaveworks/weave/db"
 	"github.com/weaveworks/weave/ipam"
+	"github.com/weaveworks/weave/ipam/tracker"
 	"github.com/weaveworks/weave/nameserver"
 	weavenet "github.com/weaveworks/weave/net"
 	"github.com/weaveworks/weave/net/address"
@@ -170,6 +171,7 @@ func main() {
 		datapathName       string
 		trustedSubnetStr   string
 		dbPrefix           string
+		isAWSVPC           bool
 
 		defaultDockerHost = "unix:///var/run/docker.sock"
 	)
@@ -208,6 +210,7 @@ func main() {
 	mflag.StringVar(&datapathName, []string{"-datapath"}, "", "ODP datapath name")
 	mflag.StringVar(&trustedSubnetStr, []string{"-trusted-subnets"}, "", "comma-separated list of trusted subnets in CIDR notation")
 	mflag.StringVar(&dbPrefix, []string{"-db-prefix"}, "/weavedb/weave", "pathname/prefix of filename to store data")
+	mflag.BoolVar(&isAWSVPC, []string{"#awsvpc", "-awsvpc"}, false, "use AWS VPC for routing")
 
 	// crude way of detecting that we probably have been started in a
 	// container, with `weave launch` --> suppress misleading paths in
@@ -250,7 +253,7 @@ func main() {
 		networkConfig.PacketLogging = nopPacketLogging{}
 	}
 
-	overlay, bridge := createOverlay(datapathName, ifaceName, config.Host, config.Port, bufSzMB)
+	overlay, bridge := createOverlay(datapathName, ifaceName, isAWSVPC, config.Host, config.Port, bufSzMB)
 	networkConfig.Bridge = bridge
 
 	name := peerName(routerName, bridge.Interface())
@@ -302,7 +305,15 @@ func main() {
 		defaultSubnet address.CIDR
 	)
 	if ipamConfig.Enabled() {
-		allocator, defaultSubnet = createAllocator(router, ipamConfig, db, isKnownPeer)
+		var t tracker.LocalRangeTracker
+		if isAWSVPC {
+			Log.Infoln("Creating AWSVPC LocalRangeTracker")
+			t, err = tracker.NewAWSVPCTracker()
+			if err != nil {
+				Log.Fatalf("Cannot create AWSVPC LocalRangeTracker: %s", err)
+			}
+		}
+		allocator, defaultSubnet = createAllocator(router, ipamConfig, db, t, isKnownPeer)
 		observeContainers(allocator)
 		ids, err := dockerCli.AllContainerIDs()
 		checkFatal(err)
@@ -388,10 +399,18 @@ func (nopPacketLogging) LogPacket(string, weave.PacketKey) {
 func (nopPacketLogging) LogForwardPacket(string, weave.ForwardPacketKey) {
 }
 
-func createOverlay(datapathName string, ifaceName string, host string, port int, bufSzMB int) (weave.NetworkOverlay, weave.Bridge) {
+func createOverlay(datapathName string, ifaceName string, isAWSVPC bool, host string, port int, bufSzMB int) (weave.NetworkOverlay, weave.Bridge) {
 	overlay := weave.NewOverlaySwitch()
 	var bridge weave.Bridge
+	var ignoreSleeve bool
+
 	switch {
+	case isAWSVPC:
+		vpc := weave.NewAWSVPC()
+		overlay.Add("awsvpc", vpc)
+		bridge = weave.NullBridge{}
+		// Currently, we do not support any overlay with AWSVPC
+		ignoreSleeve = true
 	case datapathName != "" && ifaceName != "":
 		Log.Fatal("At most one of --datapath and --iface must be specified.")
 	case datapathName != "":
@@ -409,13 +428,17 @@ func createOverlay(datapathName string, ifaceName string, host string, port int,
 	default:
 		bridge = weave.NullBridge{}
 	}
-	sleeve := weave.NewSleeveOverlay(host, port)
-	overlay.Add("sleeve", sleeve)
-	overlay.SetCompatOverlay(sleeve)
+
+	if !ignoreSleeve {
+		sleeve := weave.NewSleeveOverlay(host, port)
+		overlay.Add("sleeve", sleeve)
+		overlay.SetCompatOverlay(sleeve)
+	}
+
 	return overlay, bridge
 }
 
-func createAllocator(router *weave.NetworkRouter, config ipamConfig, db db.DB, isKnownPeer func(mesh.PeerName) bool) (*ipam.Allocator, address.CIDR) {
+func createAllocator(router *weave.NetworkRouter, config ipamConfig, db db.DB, track tracker.LocalRangeTracker, isKnownPeer func(mesh.PeerName) bool) (*ipam.Allocator, address.CIDR) {
 	ipRange, err := ipam.ParseCIDRSubnet(config.IPRangeCIDR)
 	checkFatal(err)
 	defaultSubnet := ipRange
@@ -437,6 +460,7 @@ func createAllocator(router *weave.NetworkRouter, config ipamConfig, db db.DB, i
 		Quorum:      func() uint { return determineQuorum(config.PeerCount, router) },
 		Db:          db,
 		IsKnownPeer: isKnownPeer,
+		Tracker:     track,
 	}
 
 	allocator := ipam.NewAllocator(c)

router/awsvpc.go

@@ -0,0 +1,75 @@
+package router
+
+// A dummy overlay for the AWSVPC underlay to make `weave status` to return
+// a valid information about peer connections.
+
+import (
+	"github.com/weaveworks/mesh"
+)
+
+// mesh.OverlayConnection
+
+type AWSVPCConnection struct {
+	establishedChan chan struct{}
+	errorChan       chan error
+}
+
+func (conn *AWSVPCConnection) Confirm() {
+	// We close the channel to notify mesh that the connection has been established.
+	close(conn.establishedChan)
+}
+
+func (conn *AWSVPCConnection) EstablishedChannel() <-chan struct{} {
+	return conn.establishedChan
+}
+
+func (conn *AWSVPCConnection) ErrorChannel() <-chan error {
+	return conn.errorChan
+}
+
+func (conn *AWSVPCConnection) Stop() {}
+
+func (conn *AWSVPCConnection) ControlMessage(tag byte, msg []byte) {
+}
+
+func (conn *AWSVPCConnection) DisplayName() string {
+	return "awsvpc"
+}
+
+// OverlayForwarder
+
+func (conn *AWSVPCConnection) Forward(key ForwardPacketKey) FlowOp {
+	return DiscardingFlowOp{}
+}
+
+type AWSVPC struct{}
+
+func NewAWSVPC() AWSVPC {
+	return AWSVPC{}
+}
+
+// mesh.Overlay
+
+func (vpc AWSVPC) AddFeaturesTo(features map[string]string) {}
+
+func (vpc AWSVPC) PrepareConnection(params mesh.OverlayConnectionParams) (mesh.OverlayConnection, error) {
+	conn := &AWSVPCConnection{
+		establishedChan: make(chan struct{}),
+		errorChan:       make(chan error, 1),
+	}
+	return conn, nil
+}
+
+func (vpc AWSVPC) Diagnostics() interface{} {
+	return nil
+}
+
+// NetworkOverlay
+
+func (vpc AWSVPC) InvalidateRoutes() {}
+
+func (vpc AWSVPC) InvalidateShortIDs() {}
+
+func (vpc AWSVPC) StartConsumingPackets(localPeer *mesh.Peer, peers *mesh.Peers, consumer OverlayConsumer) error {
+	return nil
+}

router/bridge.go

@@ -36,7 +36,7 @@ func (NullBridge) Interface() *net.Interface {
 }
 
 func (NullBridge) String() string {
-	return "<no bridge networking>"
+	return "no overlay bridge"
 }
 
 func (NullBridge) Stats() map[string]int {