introduce '-nodiscovery' option to disable automatic peer discovery

Closes #847.

prog/weaver/main.go

@@ -48,6 +48,7 @@ func main() {
 		pktdebug    bool
 		prof        string
 		bufSzMB     int
+		noDiscovery bool
 		httpAddr    string
 		iprangeCIDR string
 		peerCount   int
@@ -66,6 +67,7 @@ func main() {
 	flag.BoolVar(&pktdebug, "pktdebug", false, "enable per-packet debug logging")
 	flag.StringVar(&prof, "profile", "", "enable profiling and write profiles to given path")
 	flag.IntVar(&config.ConnLimit, "connlimit", 30, "connection limit (0 for unlimited)")
+	flag.BoolVar(&noDiscovery, "nodiscovery", false, "disable peer discovery")
 	flag.IntVar(&bufSzMB, "bufsz", 8, "capture buffer size in MB")
 	flag.StringVar(&httpAddr, "httpaddr", fmt.Sprintf(":%d", weave.HTTPPort), "address to bind HTTP interface to (disabled if blank, absolute path indicates unix domain socket)")
 	flag.StringVar(&iprangeCIDR, "iprange", "", "IP address range to allocate within, in CIDR notation")
@@ -129,6 +131,7 @@ func main() {
 
 	config.BufSz = bufSzMB * 1024 * 1024
 	config.LogFrame = logFrameFunc(pktdebug)
+	config.PeerDiscovery = !noDiscovery
 
 	router := weave.NewRouter(config, name, nickName)
 	log.Println("Our name is", router.Ourself)

router/connection_maker.go

@@ -20,6 +20,7 @@ type ConnectionMaker struct {
 	ourself     *LocalPeer
 	peers       *Peers
 	port        int
+	discovery   bool
 	targets     map[string]*Target
 	directPeers peerAddrs
 	actionChan  chan<- ConnectionMakerAction
@@ -35,11 +36,12 @@ type Target struct {
 
 type ConnectionMakerAction func() bool
 
-func NewConnectionMaker(ourself *LocalPeer, peers *Peers, port int) *ConnectionMaker {
+func NewConnectionMaker(ourself *LocalPeer, peers *Peers, port int, discovery bool) *ConnectionMaker {
 	return &ConnectionMaker{
 		ourself:     ourself,
 		peers:       peers,
 		port:        port,
+		discovery:   discovery,
 		directPeers: peerAddrs{},
 		targets:     make(map[string]*Target)}
 }
@@ -217,7 +219,9 @@ func (cm *ConnectionMaker) checkStateAndAttemptConnections() time.Duration {
 
 	// Add targets for peers that someone else is connected to, but we
 	// aren't
-	cm.addPeerTargets(ourConnectedPeers, addTarget)
+	if cm.discovery {
+		cm.addPeerTargets(ourConnectedPeers, addTarget)
+	}
 
 	return cm.connectToTargets(validTarget, directTarget)
 }

router/json.go

@@ -8,16 +8,17 @@ import (
 
 func (router *Router) StatusJSON(version string) ([]byte, error) {
 	return json.Marshal(struct {
-		Version    string
-		Encryption bool
-		Name       string
-		NickName   string
-		Interface  string
-		Macs       *MacCache
-		Peers      *Peers
-		Routes     *Routes
+		Version       string
+		Encryption    bool
+		PeerDiscovery bool
+		Name          string
+		NickName      string
+		Interface     string
+		Macs          *MacCache
+		Peers         *Peers
+		Routes        *Routes
 		ConnectionMakerStatus
-	}{version, router.UsingPassword(), router.Ourself.Name.String(), router.Ourself.NickName, fmt.Sprintf("%v", router.Iface), router.Macs, router.Peers, router.Routes, router.ConnectionMaker.Status()})
+	}{version, router.UsingPassword(), router.PeerDiscovery, router.Ourself.Name.String(), router.Ourself.NickName, fmt.Sprintf("%v", router.Iface), router.Macs, router.Peers, router.Routes, router.ConnectionMaker.Status()})
 }
 
 func (cache *MacCache) MarshalJSON() ([]byte, error) {

router/router.go

@@ -29,12 +29,13 @@ const (
 type LogFrameFunc func(string, []byte, *layers.Ethernet)
 
 type Config struct {
-	Port      int
-	Iface     *net.Interface
-	Password  []byte
-	ConnLimit int
-	BufSz     int
-	LogFrame  LogFrameFunc
+	Port          int
+	Iface         *net.Interface
+	Password      []byte
+	ConnLimit     int
+	PeerDiscovery bool
+	BufSz         int
+	LogFrame      LogFrameFunc
 }
 
 type Router struct {
@@ -76,7 +77,7 @@ func NewRouter(config Config, name PeerName, nickName string) *Router {
 	router.Peers = NewPeers(router.Ourself, onPeerGC)
 	router.Peers.FetchWithDefault(router.Ourself.Peer)
 	router.Routes = NewRoutes(router.Ourself, router.Peers)
-	router.ConnectionMaker = NewConnectionMaker(router.Ourself, router.Peers, router.Port)
+	router.ConnectionMaker = NewConnectionMaker(router.Ourself, router.Peers, router.Port, router.PeerDiscovery)
 	router.TopologyGossip = router.NewGossip("topology", router)
 	return router
 }
@@ -116,6 +117,7 @@ func (router *Router) Status() string {
 	var buf bytes.Buffer
 	fmt.Fprintln(&buf, "Our name is", router.Ourself)
 	fmt.Fprintln(&buf, "Encryption", OnOff(router.UsingPassword()))
+	fmt.Fprintln(&buf, "Peer discovery", OnOff(router.PeerDiscovery))
 	fmt.Fprintln(&buf, "Sniffing traffic on", router.Iface)
 	fmt.Fprintf(&buf, "MACs:\n%s", router.Macs)
 	fmt.Fprintf(&buf, "Peers:\n%s", router.Peers)

site/features.md

@@ -377,6 +377,11 @@ and the new hosts will be added, when one runs
 
     host# weave connect --replace $NEW_HOST1 $NEW_HOST2
 
+For complete control over the peer topology, automatic discovery can
+be disabled with the `-nodiscovery` option to `weave launch`. In this
+mode, weave will only connect to the addresses specified at launch
+time and with `weave connect`.
+
 ### <a name="container-mobility"></a>Container mobility
 
 Containers can be moved between hosts without requiring any

site/troubleshooting.md

@@ -63,6 +63,7 @@ This produces output like:
 weave router 0.7.0
 Our name is 7a:f4:56:87:76:3b(weave01)
 Encryption off
+Peer discovery on
 Sniffing traffic on &{39 65535 ethwe ae:e3:07:9c:8c:d4 up|broadcast|multicast}
 MACs:
 ba:8c:b9:dc:e1:c9 -> 7a:f4:56:87:76:3b(weave01) (2014-10-23 16:39:19.482338935 +0000 UTC)
@@ -104,6 +105,10 @@ The 'Encryption' line indicates whether
 [encryption](features.html#security) is in use for communication
 between peers.
 
+The 'Peer discovery' line indicates whether
+[automatic peer discovery](features.html#dynamic-topologies) is
+enabled (which is the default).
+
 The 'MACs' section lists all MAC addresses known to this router. These
 identify containers in the weave network, as well as points for
 [host network integration](features.html#host-network-integration). For

weave

@@ -25,7 +25,8 @@ CIDR_REGEXP="$IP_REGEXP/[0-9]{1,2}"
 usage() {
     echo "Usage:"
     echo "weave setup"
-    echo "weave launch       [-password <password>] [-nickname <nickname>] [-iprange <cidr>] <peer> ..."
+    echo "weave launch       [-password <password>] [-nickname <nickname>] [-nodiscovery]"
+    echo "                       [-iprange <cidr>] <peer> ..."
     echo "weave launch-dns   <cidr>"
     echo "weave launch-proxy [-H <docker_endpoint>] [--with-dns] [--with-ipam]"
     echo "weave connect      [--replace] [<peer> ...]"