Peer Discovery via a web service

net/if.go

@@ -82,3 +82,25 @@ func findInterface(ifaceName string) (iface *net.Interface, err error) {
 	}
 	return
 }
+
+func LocalAddresses() ([]*net.IPNet, error) {
+	links, err := netlink.LinkList()
+	if err != nil {
+		return nil, err
+	}
+
+	retval := []*net.IPNet{}
+	for _, link := range links {
+		if _, isBridge := link.(*netlink.Bridge); isBridge || (link.Attrs().Flags&net.FlagLoopback) != 0 {
+			continue
+		}
+		addrs, err := netlink.AddrList(link, netlink.FAMILY_V4)
+		if err != nil {
+			return nil, err
+		}
+		for _, addr := range addrs {
+			retval = append(retval, addr.IPNet)
+		}
+	}
+	return retval, nil
+}

prog/weaver/discovery.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+)
+
+// TODO: move these definitions somewhere more shareable
+type PeerUpdateRequest struct {
+	Name      string   `json:"peername"`
+	Nickname  string   `json:"nickname"`  // optional
+	Addresses []string `json:"addresses"` // can be empty
+}
+
+type PeerUpdateResponse struct {
+	Addresses []string `json:"addresses"`
+}
+
+var httpClient = &http.Client{Timeout: 30 * time.Second}
+
+func do(verb string, discoveryEndpoint, token string, request interface{}, response interface{}) error {
+	body := new(bytes.Buffer)
+	err := json.NewEncoder(body).Encode(request)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequest(verb, discoveryEndpoint+"/peer", body)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Authorization", fmt.Sprintf("Scope-Probe token=%s", token))
+	req.Header.Set("X-Weave-Net-Version", version)
+	req.Header.Set("Content-Type", "application/json")
+	Log.Printf("Calling peer discovery %s with %s", req.URL, request)
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		rbody, _ := ioutil.ReadAll(resp.Body)
+		return errors.New(resp.Status + ": " + string(rbody))
+	}
+	if response == nil {
+		return nil
+	}
+	err = json.NewDecoder(resp.Body).Decode(response)
+	Log.Printf("peer discovery result: (%s) %v", err, response)
+	return err
+}
+
+func peerDiscoveryUpdate(discoveryEndpoint, token, peername, nickname string, addresses []string) ([]string, error) {
+	request := PeerUpdateRequest{
+		Name:      peername,
+		Nickname:  nickname,
+		Addresses: addresses,
+	}
+	var updateResponse PeerUpdateResponse
+	err := do("POST", discoveryEndpoint, token, request, &updateResponse)
+	return updateResponse.Addresses, err
+}

prog/weaver/main.go

@@ -143,6 +143,9 @@ func main() {
 		trustedSubnetStr   string
 		dbPrefix           string
 		isAWSVPC           bool
+		discoveryEndpoint  string
+		token              string
+		advertiseAddress   string
 
 		defaultDockerHost = "unix:///var/run/docker.sock"
 	)
@@ -184,6 +187,9 @@ func main() {
 	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"}, false, "use AWS VPC for routing")
+	mflag.StringVar(&discoveryEndpoint, []string{"-peer-discovery-url"}, "https://cloud.weave.works/api/weavenet", "url for peer discovery")
+	mflag.StringVar(&token, []string{"-token"}, "", "token for peer discovery")
+	mflag.StringVar(&advertiseAddress, []string{"-advertise-address"}, "", "address to advertise for peer discovery")
 
 	// crude way of detecting that we probably have been started in a
 	// container, with `weave launch` --> suppress misleading paths in
@@ -257,7 +263,21 @@ func main() {
 	router := weave.NewNetworkRouter(config, networkConfig, name, nickName, overlay, db)
 	Log.Println("Our name is", router.Ourself)
 
-	if peers, err = router.InitialPeers(resume, peers); err != nil {
+	if token != "" {
+		var addresses []string
+		if advertiseAddress == "" {
+			localAddrs, err := weavenet.LocalAddresses()
+			checkFatal(err)
+			for _, addr := range localAddrs {
+				addresses = append(addresses, addr.IP.String())
+			}
+		} else {
+			addresses = strings.Split(advertiseAddress, ",")
+		}
+		discoveredPeers, err := peerDiscoveryUpdate(discoveryEndpoint, token, name.String(), nickName, addresses)
+		checkFatal(err) // TODO: what if it is a transient error, and we are restarting?
+		peers = append(peers, discoveredPeers...)
+	} else if peers, err = router.InitialPeers(resume, peers); err != nil {
 		Log.Fatal("Unable to get initial peer set: ", err)
 	}
 
@@ -376,7 +396,7 @@ func options() map[string]string {
 	mflag.Visit(func(f *mflag.Flag) {
 		value := f.Value.String()
 		name := canonicalName(f)
-		if name == "password" {
+		if name == "password" || name == "token" {
 			value = "<redacted>"
 		}
 		options[name] = value