Merge pull request #345 from micro/gossip

Gossip
2018-12-06 18:22:52 +00:00 · 2018-12-06 18:22:52 +00:00 · cf8c059711
commit cf8c059711
parent 489573afb9 b343420af6
10 changed files with 1042 additions and 7 deletions
--- a/cmd/cmd.go
+++ b/cmd/cmd.go
@ -10,6 +10,7 @@ import (
 	"time"

 	"github.com/micro/cli"
+	"github.com/micro/go-log"
 	"github.com/micro/go-micro/client"
 	"github.com/micro/go-micro/server"

@ -20,6 +21,7 @@ import (
 	// registries
 	"github.com/micro/go-micro/registry"
 	"github.com/micro/go-micro/registry/consul"
+	"github.com/micro/go-micro/registry/gossip"
 	"github.com/micro/go-micro/registry/mdns"

 	// selectors
@ -171,6 +173,7 @@ var (

 	DefaultRegistries = map[string]func(...registry.Option) registry.Registry{
 		"consul": consul.NewRegistry,
+		"gossip": gossip.NewRegistry,
 		"mdns":   mdns.NewRegistry,
 	}

@ -299,10 +302,15 @@ func (c *cmd) Before(ctx *cli.Context) error {
 		serverOpts = append(serverOpts, server.Registry(*c.opts.Registry))
 		clientOpts = append(clientOpts, client.Registry(*c.opts.Registry))

-		(*c.opts.Selector).Init(selector.Registry(*c.opts.Registry))
+		if err := (*c.opts.Selector).Init(selector.Registry(*c.opts.Registry)); err != nil {
+			log.Fatalf("Error configuring registry: %v", err)
+		}
+
 		clientOpts = append(clientOpts, client.Selector(*c.opts.Selector))

-		(*c.opts.Broker).Init(broker.Registry(*c.opts.Registry))
+		if err := (*c.opts.Broker).Init(broker.Registry(*c.opts.Registry)); err != nil {
+			log.Fatalf("Error configuring broker: %v", err)
+		}
 	}

 	// Set the selector
@ -347,15 +355,21 @@ func (c *cmd) Before(ctx *cli.Context) error {
 	}

 	if len(ctx.String("broker_address")) > 0 {
-		(*c.opts.Broker).Init(broker.Addrs(strings.Split(ctx.String("broker_address"), ",")...))
+		if err := (*c.opts.Broker).Init(broker.Addrs(strings.Split(ctx.String("broker_address"), ",")...)); err != nil {
+			log.Fatalf("Error configuring broker: %v", err)
+		}
 	}

 	if len(ctx.String("registry_address")) > 0 {
-		(*c.opts.Registry).Init(registry.Addrs(strings.Split(ctx.String("registry_address"), ",")...))
+		if err := (*c.opts.Registry).Init(registry.Addrs(strings.Split(ctx.String("registry_address"), ",")...)); err != nil {
+			log.Fatalf("Error configuring registry: %v", err)
+		}
 	}

 	if len(ctx.String("transport_address")) > 0 {
-		(*c.opts.Transport).Init(transport.Addrs(strings.Split(ctx.String("transport_address"), ",")...))
+		if err := (*c.opts.Transport).Init(transport.Addrs(strings.Split(ctx.String("transport_address"), ",")...)); err != nil {
+			log.Fatalf("Error configuring transport: %v", err)
+		}
 	}

 	if len(ctx.String("server_name")) > 0 {
@ -410,12 +424,16 @@ func (c *cmd) Before(ctx *cli.Context) error {
 	// We have some command line opts for the server.
 	// Lets set it up
 	if len(serverOpts) > 0 {
-		(*c.opts.Server).Init(serverOpts...)
+		if err := (*c.opts.Server).Init(serverOpts...); err != nil {
+			log.Fatalf("Error configuring server: %v", err)
+		}
 	}

 	// Use an init option?
 	if len(clientOpts) > 0 {
-		(*c.opts.Client).Init(clientOpts...)
+		if err := (*c.opts.Client).Init(clientOpts...); err != nil {
+			log.Fatalf("Error configuring client: %v", err)
+		}
 	}

 	return nil
--- a/registry/gossip/gossip.go
+++ b/registry/gossip/gossip.go
@ -0,0 +1,565 @@
+// Package Gossip provides a gossip registry based on hashicorp/memberlist
+package gossip
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/google/uuid"
+	"github.com/hashicorp/memberlist"
+	"github.com/micro/go-log"
+	"github.com/micro/go-micro/registry"
+	pb "github.com/micro/go-micro/registry/gossip/proto"
+	"github.com/mitchellh/hashstructure"
+)
+
+const (
+	addAction  = "update"
+	delAction  = "delete"
+	syncAction = "sync"
+)
+
+type broadcast struct {
+	update *pb.Update
+	notify chan<- struct{}
+}
+
+type delegate struct {
+	queue   *memberlist.TransmitLimitedQueue
+	updates chan *update
+}
+
+type gossipRegistry struct {
+	queue    *memberlist.TransmitLimitedQueue
+	updates  chan *update
+	options  registry.Options
+	member   *memberlist.Memberlist
+	interval time.Duration
+
+	sync.RWMutex
+	services map[string][]*registry.Service
+
+	s        sync.RWMutex
+	watchers map[string]chan *registry.Result
+}
+
+type update struct {
+	Update  *pb.Update
+	Service *registry.Service
+	sync    chan *registry.Service
+}
+
+var (
+	// You should change this if using secure
+	DefaultSecret = []byte("gossip")
+	ExpiryTick    = time.Second * 5
+)
+
+func configure(g *gossipRegistry, opts ...registry.Option) error {
+	// loop through address list and get valid entries
+	addrs := func(curAddrs []string) []string {
+		var newAddrs []string
+		for _, addr := range curAddrs {
+			if trimAddr := strings.TrimSpace(addr); len(trimAddr) > 0 {
+				newAddrs = append(newAddrs, trimAddr)
+			}
+		}
+		return newAddrs
+	}
+
+	// current address list
+	curAddrs := addrs(g.options.Addrs)
+
+	// parse options
+	for _, o := range opts {
+		o(&g.options)
+	}
+
+	// new address list
+	newAddrs := addrs(g.options.Addrs)
+
+	// no new nodes and existing member. no configure
+	if (len(newAddrs) == len(curAddrs)) && g.member != nil {
+		return nil
+	}
+
+	// shutdown old member
+	if g.member != nil {
+		g.member.Shutdown()
+	}
+
+	// replace addresses
+	curAddrs = newAddrs
+
+	// create a queue
+	queue := &memberlist.TransmitLimitedQueue{
+		NumNodes: func() int {
+			return len(curAddrs)
+		},
+		RetransmitMult: 3,
+	}
+
+	// machine hostname
+	hostname, _ := os.Hostname()
+
+	// create a new default config
+	c := memberlist.DefaultLocalConfig()
+
+	// set bind to random port
+	c.BindPort = 0
+
+	// set the name
+	c.Name = strings.Join([]string{"micro", hostname, uuid.New().String()}, "-")
+
+	// set the delegate
+	c.Delegate = &delegate{
+		updates: g.updates,
+		queue:   queue,
+	}
+
+	// log to dev null
+	c.LogOutput = ioutil.Discard
+
+	// set a secret key if secure
+	if g.options.Secure {
+		k, ok := g.options.Context.Value(contextSecretKey{}).([]byte)
+		if !ok {
+			// use the default secret
+			k = DefaultSecret
+		}
+		c.SecretKey = k
+	}
+
+	// TODO: set advertise addr to advertise behind nat
+
+	// create the memberlist
+	m, err := memberlist.Create(c)
+	if err != nil {
+		return err
+	}
+
+	// join the memberlist
+	if len(curAddrs) > 0 {
+		_, err := m.Join(curAddrs)
+		if err != nil {
+			return err
+		}
+	}
+
+	// set internals
+	g.queue = queue
+	g.member = m
+	g.interval = c.GossipInterval
+
+	log.Logf("Registry Listening on %s", m.LocalNode().Address())
+	return nil
+}
+
+func (b *broadcast) Invalidates(other memberlist.Broadcast) bool {
+	up := new(pb.Update)
+	if err := proto.Unmarshal(other.Message(), up); err != nil {
+		return false
+	}
+
+	// ids do not match
+	if b.update.Id == up.Id {
+		return false
+	}
+
+	// timestamps do not match
+	if b.update.Timestamp != up.Timestamp {
+		return false
+	}
+
+	// type does not match
+	if b.update.Type != up.Type {
+		return false
+	}
+
+	// invalidates
+	return true
+}
+
+func (b *broadcast) Message() []byte {
+	up, err := proto.Marshal(b.update)
+	if err != nil {
+		return nil
+	}
+	return up
+}
+
+func (b *broadcast) Finished() {
+	if b.notify != nil {
+		close(b.notify)
+	}
+}
+
+func (d *delegate) NodeMeta(limit int) []byte {
+	return []byte{}
+}
+
+func (d *delegate) NotifyMsg(b []byte) {
+	if len(b) == 0 {
+		return
+	}
+
+	go func() {
+		up := new(pb.Update)
+		if err := proto.Unmarshal(b, up); err != nil {
+			return
+		}
+
+		// only process service action
+		if up.Type != "service" {
+			return
+		}
+
+		var service *registry.Service
+
+		switch up.Metadata["Content-Type"] {
+		case "application/json":
+			if err := json.Unmarshal(up.Data, &service); err != nil {
+				return
+			}
+		// no other content type
+		default:
+			return
+		}
+
+		// send update
+		d.updates <- &update{
+			Update:  up,
+			Service: service,
+		}
+	}()
+}
+
+func (d *delegate) GetBroadcasts(overhead, limit int) [][]byte {
+	return d.queue.GetBroadcasts(overhead, limit)
+}
+
+func (d *delegate) LocalState(join bool) []byte {
+	if !join {
+		return []byte{}
+	}
+
+	syncCh := make(chan *registry.Service, 1)
+	services := map[string][]*registry.Service{}
+
+	d.updates <- &update{
+		Update: &pb.Update{
+			Action: syncAction,
+		},
+		sync: syncCh,
+	}
+
+	for srv := range syncCh {
+		services[srv.Name] = append(services[srv.Name], srv)
+	}
+
+	b, _ := json.Marshal(services)
+	return b
+}
+
+func (d *delegate) MergeRemoteState(buf []byte, join bool) {
+	if len(buf) == 0 {
+		return
+	}
+	if !join {
+		return
+	}
+
+	var services map[string][]*registry.Service
+	if err := json.Unmarshal(buf, &services); err != nil {
+		return
+	}
+
+	for _, service := range services {
+		for _, srv := range service {
+			d.updates <- &update{
+				Update:  &pb.Update{Action: addAction},
+				Service: srv,
+				sync:    nil,
+			}
+		}
+	}
+}
+
+func (g *gossipRegistry) publish(action string, services []*registry.Service) {
+	g.s.RLock()
+	for _, sub := range g.watchers {
+		go func(sub chan *registry.Result) {
+			for _, service := range services {
+				sub <- &registry.Result{Action: action, Service: service}
+			}
+		}(sub)
+	}
+	g.s.RUnlock()
+}
+
+func (g *gossipRegistry) subscribe() (chan *registry.Result, chan bool) {
+	next := make(chan *registry.Result, 10)
+	exit := make(chan bool)
+
+	id := uuid.New().String()
+
+	g.s.Lock()
+	g.watchers[id] = next
+	g.s.Unlock()
+
+	go func() {
+		<-exit
+		g.s.Lock()
+		delete(g.watchers, id)
+		close(next)
+		g.s.Unlock()
+	}()
+
+	return next, exit
+}
+
+func (g *gossipRegistry) run() {
+	var mtx sync.Mutex
+	updates := map[uint64]*update{}
+
+	// expiry loop
+	go func() {
+		t := time.NewTicker(ExpiryTick)
+		defer t.Stop()
+
+		for _ = range t.C {
+			now := uint64(time.Now().UnixNano())
+
+			mtx.Lock()
+
+			// process all the updates
+			for k, v := range updates {
+				// check if expiry time has passed
+				if d := (v.Update.Timestamp + v.Update.Expires); d < now {
+					// delete from records
+					delete(updates, k)
+					// set to delete
+					v.Update.Action = delAction
+					// fire a new update
+					g.updates <- v
+				}
+			}
+
+			mtx.Unlock()
+		}
+	}()
+
+	// process the updates
+	for u := range g.updates {
+		switch u.Update.Action {
+		case addAction:
+			g.Lock()
+			if service, ok := g.services[u.Service.Name]; !ok {
+				g.services[u.Service.Name] = []*registry.Service{u.Service}
+
+			} else {
+				g.services[u.Service.Name] = addServices(service, []*registry.Service{u.Service})
+			}
+			g.Unlock()
+
+			// publish update to watchers
+			go g.publish(addAction, []*registry.Service{u.Service})
+
+			// we need to expire the node at some point in the future
+			if u.Update.Expires > 0 {
+				// create a hash of this service
+				if hash, err := hashstructure.Hash(u.Service, nil); err == nil {
+					mtx.Lock()
+					updates[hash] = u
+					mtx.Unlock()
+				}
+			}
+		case delAction:
+			g.Lock()
+			if service, ok := g.services[u.Service.Name]; ok {
+				if services := delServices(service, []*registry.Service{u.Service}); len(services) == 0 {
+					delete(g.services, u.Service.Name)
+				} else {
+					g.services[u.Service.Name] = services
+				}
+			}
+			g.Unlock()
+
+			// publish update to watchers
+			go g.publish(delAction, []*registry.Service{u.Service})
+
+			// delete from expiry checks
+			if hash, err := hashstructure.Hash(u.Service, nil); err == nil {
+				mtx.Lock()
+				delete(updates, hash)
+				mtx.Unlock()
+			}
+		case syncAction:
+			// no sync channel provided
+			if u.sync == nil {
+				continue
+			}
+
+			g.RLock()
+
+			// push all services through the sync chan
+			for _, service := range g.services {
+				for _, srv := range service {
+					u.sync <- srv
+				}
+
+				// publish to watchers
+				go g.publish(addAction, service)
+			}
+
+			g.RUnlock()
+
+			// close the sync chan
+			close(u.sync)
+		}
+	}
+}
+
+func (g *gossipRegistry) Init(opts ...registry.Option) error {
+	return configure(g, opts...)
+}
+
+func (g *gossipRegistry) Options() registry.Options {
+	return g.options
+}
+
+func (g *gossipRegistry) Register(s *registry.Service, opts ...registry.RegisterOption) error {
+	b, err := json.Marshal(s)
+	if err != nil {
+		return err
+	}
+
+	g.Lock()
+	if service, ok := g.services[s.Name]; !ok {
+		g.services[s.Name] = []*registry.Service{s}
+	} else {
+		g.services[s.Name] = addServices(service, []*registry.Service{s})
+	}
+	g.Unlock()
+
+	var options registry.RegisterOptions
+	for _, o := range opts {
+		o(&options)
+	}
+
+	up := &pb.Update{
+		Id:        uuid.New().String(),
+		Timestamp: uint64(time.Now().UnixNano()),
+		Expires:   uint64(options.TTL.Nanoseconds()),
+		Action:    "update",
+		Type:      "service",
+		Metadata: map[string]string{
+			"Content-Type": "application/json",
+		},
+		Data: b,
+	}
+
+	g.queue.QueueBroadcast(&broadcast{
+		update: up,
+		notify: nil,
+	})
+
+	// wait
+	<-time.After(g.interval * 2)
+
+	return nil
+}
+
+func (g *gossipRegistry) Deregister(s *registry.Service) error {
+	b, err := json.Marshal(s)
+	if err != nil {
+		return err
+	}
+
+	g.Lock()
+	if service, ok := g.services[s.Name]; ok {
+		if services := delServices(service, []*registry.Service{s}); len(services) == 0 {
+			delete(g.services, s.Name)
+		} else {
+			g.services[s.Name] = services
+		}
+	}
+	g.Unlock()
+
+	up := &pb.Update{
+		Id:        uuid.New().String(),
+		Timestamp: uint64(time.Now().UnixNano()),
+		Action:    "delete",
+		Type:      "service",
+		Metadata: map[string]string{
+			"Content-Type": "application/json",
+		},
+		Data: b,
+	}
+
+	g.queue.QueueBroadcast(&broadcast{
+		update: up,
+		notify: nil,
+	})
+
+	// wait
+	<-time.After(g.interval * 2)
+
+	return nil
+}
+
+func (g *gossipRegistry) GetService(name string) ([]*registry.Service, error) {
+	g.RLock()
+	service, ok := g.services[name]
+	g.RUnlock()
+	if !ok {
+		return nil, registry.ErrNotFound
+	}
+	return service, nil
+}
+
+func (g *gossipRegistry) ListServices() ([]*registry.Service, error) {
+	var services []*registry.Service
+	g.RLock()
+	for _, service := range g.services {
+		services = append(services, service...)
+	}
+	g.RUnlock()
+	return services, nil
+}
+
+func (g *gossipRegistry) Watch(opts ...registry.WatchOption) (registry.Watcher, error) {
+	n, e := g.subscribe()
+	return newGossipWatcher(n, e, opts...)
+}
+
+func (g *gossipRegistry) String() string {
+	return "gossip"
+}
+
+func NewRegistry(opts ...registry.Option) registry.Registry {
+	gossip := &gossipRegistry{
+		options:  registry.Options{},
+		updates:  make(chan *update, 100),
+		services: make(map[string][]*registry.Service),
+		watchers: make(map[string]chan *registry.Result),
+	}
+
+	// configure the gossiper
+	if err := configure(gossip, opts...); err != nil {
+		log.Fatal("Error configuring registry: %v", err)
+	}
+
+	// run the updater
+	go gossip.run()
+
+	// wait for setup
+	<-time.After(gossip.interval * 2)
+
+	return gossip
+}
--- a/registry/gossip/options.go
+++ b/registry/gossip/options.go
@ -0,0 +1,17 @@
+package gossip
+
+import (
+	"context"
+
+	"github.com/micro/go-micro/registry"
+)
+
+type contextSecretKey struct{}
+
+// Secret specifies an encryption key. The value should be either
+// 16, 24, or 32 bytes to select AES-128, AES-192, or AES-256.
+func Secret(k []byte) registry.Option {
+	return func(o *registry.Options) {
+		o.Context = context.WithValue(o.Context, contextSecretKey{}, k)
+	}
+}
--- a/registry/gossip/proto/gossip.micro.go
+++ b/registry/gossip/proto/gossip.micro.go
@ -0,0 +1,28 @@
+// Code generated by protoc-gen-micro. DO NOT EDIT.
+// source: github.com/micro/go-micro/registry/gossip/proto/gossip.proto
+
+/*
+Package gossip is a generated protocol buffer package.
+
+It is generated from these files:
+	github.com/micro/go-micro/registry/gossip/proto/gossip.proto
+
+It has these top-level messages:
+	Update
+*/
+package gossip
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
--- a/registry/gossip/proto/gossip.pb.go
+++ b/registry/gossip/proto/gossip.pb.go
@ -0,0 +1,145 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: github.com/micro/go-micro/registry/gossip/proto/gossip.proto
+
+package gossip
+
+import (
+	fmt "fmt"
+	proto "github.com/golang/protobuf/proto"
+	math "math"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
+
+// Update is the message broadcast
+type Update struct {
+	// unique id of update
+	Id string `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
+	// unix nano timestamp of update
+	Timestamp uint64 `protobuf:"varint,2,opt,name=timestamp,proto3" json:"timestamp,omitempty"`
+	// time to live for entry
+	Expires uint64 `protobuf:"varint,3,opt,name=expires,proto3" json:"expires,omitempty"`
+	// type of update; service
+	Type string `protobuf:"bytes,4,opt,name=type,proto3" json:"type,omitempty"`
+	// what action is taken; add, del, put
+	Action string `protobuf:"bytes,5,opt,name=action,proto3" json:"action,omitempty"`
+	// any other associated metadata about the data
+	Metadata map[string]string `protobuf:"bytes,6,rep,name=metadata,proto3" json:"metadata,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	// the payload data;
+	Data                 []byte   `protobuf:"bytes,7,opt,name=data,proto3" json:"data,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *Update) Reset()         { *m = Update{} }
+func (m *Update) String() string { return proto.CompactTextString(m) }
+func (*Update) ProtoMessage()    {}
+func (*Update) Descriptor() ([]byte, []int) {
+	return fileDescriptor_18cba623e76e57f3, []int{0}
+}
+
+func (m *Update) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_Update.Unmarshal(m, b)
+}
+func (m *Update) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_Update.Marshal(b, m, deterministic)
+}
+func (m *Update) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_Update.Merge(m, src)
+}
+func (m *Update) XXX_Size() int {
+	return xxx_messageInfo_Update.Size(m)
+}
+func (m *Update) XXX_DiscardUnknown() {
+	xxx_messageInfo_Update.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_Update proto.InternalMessageInfo
+
+func (m *Update) GetId() string {
+	if m != nil {
+		return m.Id
+	}
+	return ""
+}
+
+func (m *Update) GetTimestamp() uint64 {
+	if m != nil {
+		return m.Timestamp
+	}
+	return 0
+}
+
+func (m *Update) GetExpires() uint64 {
+	if m != nil {
+		return m.Expires
+	}
+	return 0
+}
+
+func (m *Update) GetType() string {
+	if m != nil {
+		return m.Type
+	}
+	return ""
+}
+
+func (m *Update) GetAction() string {
+	if m != nil {
+		return m.Action
+	}
+	return ""
+}
+
+func (m *Update) GetMetadata() map[string]string {
+	if m != nil {
+		return m.Metadata
+	}
+	return nil
+}
+
+func (m *Update) GetData() []byte {
+	if m != nil {
+		return m.Data
+	}
+	return nil
+}
+
+func init() {
+	proto.RegisterType((*Update)(nil), "gossip.Update")
+	proto.RegisterMapType((map[string]string)(nil), "gossip.Update.MetadataEntry")
+}
+
+func init() {
+	proto.RegisterFile("github.com/micro/go-micro/registry/gossip/proto/gossip.proto", fileDescriptor_18cba623e76e57f3)
+}
+
+var fileDescriptor_18cba623e76e57f3 = []byte{
+	// 251 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x54, 0x90, 0xcf, 0x4a, 0xc4, 0x30,
+	0x10, 0x87, 0x69, 0xb6, 0x9b, 0xb5, 0xe3, 0x1f, 0x64, 0x10, 0x09, 0xb2, 0x87, 0xe2, 0xa9, 0x17,
+	0x5b, 0xd0, 0xcb, 0xa2, 0x5e, 0x3d, 0x7a, 0x09, 0xf8, 0x00, 0xd9, 0x36, 0xd4, 0xa0, 0xd9, 0x84,
+	0x64, 0x56, 0xec, 0x13, 0xf8, 0xda, 0xb2, 0x69, 0x54, 0xbc, 0x7d, 0xdf, 0xcc, 0x24, 0x99, 0x5f,
+	0xe0, 0x71, 0x34, 0xf4, 0xba, 0xdf, 0xb6, 0xbd, 0xb3, 0x9d, 0x35, 0x7d, 0x70, 0xdd, 0xe8, 0x6e,
+	0x66, 0x08, 0x7a, 0x34, 0x91, 0xc2, 0xd4, 0x8d, 0x2e, 0x46, 0xe3, 0x3b, 0x1f, 0x1c, 0xb9, 0x2c,
+	0x6d, 0x12, 0xe4, 0xb3, 0x5d, 0x7f, 0x31, 0xe0, 0x2f, 0x7e, 0x50, 0xa4, 0xf1, 0x0c, 0x98, 0x19,
+	0x44, 0x51, 0x17, 0x4d, 0x25, 0x99, 0x19, 0x70, 0x0d, 0x15, 0x19, 0xab, 0x23, 0x29, 0xeb, 0x05,
+	0xab, 0x8b, 0xa6, 0x94, 0x7f, 0x05, 0x14, 0xb0, 0xd2, 0x9f, 0xde, 0x04, 0x1d, 0xc5, 0x22, 0xf5,
+	0x7e, 0x14, 0x11, 0x4a, 0x9a, 0xbc, 0x16, 0x65, 0xba, 0x29, 0x31, 0x5e, 0x02, 0x57, 0x3d, 0x19,
+	0xb7, 0x13, 0xcb, 0x54, 0xcd, 0x86, 0x1b, 0x38, 0xb2, 0x9a, 0xd4, 0xa0, 0x48, 0x09, 0x5e, 0x2f,
+	0x9a, 0xe3, 0xdb, 0x75, 0x9b, 0xf7, 0x9c, 0xb7, 0x6a, 0x9f, 0x73, 0xfb, 0x69, 0x47, 0x61, 0x92,
+	0xbf, 0xd3, 0x87, 0x57, 0xd2, 0xa9, 0x55, 0x5d, 0x34, 0x27, 0x32, 0xf1, 0xd5, 0x03, 0x9c, 0xfe,
+	0x1b, 0xc7, 0x73, 0x58, 0xbc, 0xe9, 0x29, 0x67, 0x3a, 0x20, 0x5e, 0xc0, 0xf2, 0x43, 0xbd, 0xef,
+	0x75, 0x0a, 0x54, 0xc9, 0x59, 0xee, 0xd9, 0xa6, 0xd8, 0xf2, 0xf4, 0x31, 0x77, 0xdf, 0x01, 0x00,
+	0x00, 0xff, 0xff, 0x06, 0x6e, 0x00, 0x3c, 0x58, 0x01, 0x00, 0x00,
+}
--- a/registry/gossip/proto/gossip.proto
+++ b/registry/gossip/proto/gossip.proto
@ -0,0 +1,21 @@
+syntax = "proto3";
+
+package gossip;
+
+// Update is the message broadcast
+message Update {
+	// unique id of update
+	string id = 1;
+	// unix nano timestamp of update
+	uint64 timestamp = 2;
+	// time to live for entry
+	uint64 expires = 3;
+	// type of update; service
+	string type = 4;
+	// what action is taken; add, del, put
+	string action = 5;
+	// any other associated metadata about the data
+	map<string, string> metadata = 6;
+	// the payload data;
+	bytes data = 7;
+}
--- a/registry/gossip/util.go
+++ b/registry/gossip/util.go
@ -0,0 +1,109 @@
+package gossip
+
+import (
+	"github.com/micro/go-micro/registry"
+)
+
+func cp(current []*registry.Service) []*registry.Service {
+	var services []*registry.Service
+
+	for _, service := range current {
+		// copy service
+		s := new(registry.Service)
+		*s = *service
+
+		// copy nodes
+		var nodes []*registry.Node
+		for _, node := range service.Nodes {
+			n := new(registry.Node)
+			*n = *node
+			nodes = append(nodes, n)
+		}
+		s.Nodes = nodes
+
+		// copy endpoints
+		var eps []*registry.Endpoint
+		for _, ep := range service.Endpoints {
+			e := new(registry.Endpoint)
+			*e = *ep
+			eps = append(eps, e)
+		}
+		s.Endpoints = eps
+
+		// append service
+		services = append(services, s)
+	}
+
+	return services
+}
+
+func addNodes(old, neu []*registry.Node) []*registry.Node {
+	for _, n := range neu {
+		var seen bool
+		for i, o := range old {
+			if o.Id == n.Id {
+				seen = true
+				old[i] = n
+				break
+			}
+		}
+		if !seen {
+			old = append(old, n)
+		}
+	}
+	return old
+}
+
+func addServices(old, neu []*registry.Service) []*registry.Service {
+	for _, s := range neu {
+		var seen bool
+		for i, o := range old {
+			if o.Version == s.Version {
+				s.Nodes = addNodes(o.Nodes, s.Nodes)
+				seen = true
+				old[i] = s
+				break
+			}
+		}
+		if !seen {
+			old = append(old, s)
+		}
+	}
+	return old
+}
+
+func delNodes(old, del []*registry.Node) []*registry.Node {
+	var nodes []*registry.Node
+	for _, o := range old {
+		var rem bool
+		for _, n := range del {
+			if o.Id == n.Id {
+				rem = true
+				break
+			}
+		}
+		if !rem {
+			nodes = append(nodes, o)
+		}
+	}
+	return nodes
+}
+
+func delServices(old, del []*registry.Service) []*registry.Service {
+	var services []*registry.Service
+	for i, o := range old {
+		var rem bool
+		for _, s := range del {
+			if o.Version == s.Version {
+				old[i].Nodes = delNodes(o.Nodes, s.Nodes)
+				if len(old[i].Nodes) == 0 {
+					rem = true
+				}
+			}
+		}
+		if !rem {
+			services = append(services, o)
+		}
+	}
+	return services
+}
--- a/registry/gossip/util_test.go
+++ b/registry/gossip/util_test.go
@ -0,0 +1,78 @@
+package gossip
+
+import (
+	"testing"
+
+	"github.com/micro/go-micro/registry"
+)
+
+func TestDelServices(t *testing.T) {
+	services := []*registry.Service{
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost",
+					Port:    9999,
+				},
+			},
+		},
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost",
+					Port:    6666,
+				},
+			},
+		},
+	}
+
+	servs := delServices([]*registry.Service{services[0]}, []*registry.Service{services[1]})
+	if i := len(servs); i > 0 {
+		t.Errorf("Expected 0 nodes, got %d: %+v", i, servs)
+	}
+	t.Logf("Services %+v", servs)
+}
+
+func TestDelNodes(t *testing.T) {
+	services := []*registry.Service{
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost",
+					Port:    9999,
+				},
+				{
+					Id:      "foo-321",
+					Address: "localhost",
+					Port:    6666,
+				},
+			},
+		},
+		{
+			Name:    "foo",
+			Version: "1.0.0",
+			Nodes: []*registry.Node{
+				{
+					Id:      "foo-123",
+					Address: "localhost",
+					Port:    6666,
+				},
+			},
+		},
+	}
+
+	nodes := delNodes(services[0].Nodes, services[1].Nodes)
+	if i := len(nodes); i != 1 {
+		t.Errorf("Expected only 1 node, got %d: %+v", i, nodes)
+	}
+	t.Logf("Nodes %+v", nodes)
+}
--- a/registry/gossip/watcher.go
+++ b/registry/gossip/watcher.go
@ -0,0 +1,51 @@
+package gossip
+
+import (
+	"github.com/micro/go-micro/registry"
+)
+
+type gossipWatcher struct {
+	wo   registry.WatchOptions
+	next chan *registry.Result
+	stop chan bool
+}
+
+func newGossipWatcher(ch chan *registry.Result, stop chan bool, opts ...registry.WatchOption) (registry.Watcher, error) {
+	var wo registry.WatchOptions
+	for _, o := range opts {
+		o(&wo)
+	}
+
+	return &gossipWatcher{
+		wo:   wo,
+		next: ch,
+		stop: stop,
+	}, nil
+}
+
+func (m *gossipWatcher) Next() (*registry.Result, error) {
+	for {
+		select {
+		case r, ok := <-m.next:
+			if !ok {
+				return nil, registry.ErrWatcherStopped
+			}
+			// check watch options
+			if len(m.wo.Service) > 0 && r.Service.Name != m.wo.Service {
+				continue
+			}
+			return r, nil
+		case <-m.stop:
+			return nil, registry.ErrWatcherStopped
+		}
+	}
+}
+
+func (m *gossipWatcher) Stop() {
+	select {
+	case <-m.stop:
+		return
+	default:
+		close(m.stop)
+	}
+}
--- a/registry/registry.go
+++ b/registry/registry.go
@ -28,7 +28,10 @@ type WatchOption func(*WatchOptions)
 var (
 	DefaultRegistry = newConsulRegistry()

+	// Not found error when GetService is called
 	ErrNotFound = errors.New("not found")
+	// Watcher stopped error when watcher is stopped
+	ErrWatcherStopped = errors.New("watcher stopped")
 )

 func NewRegistry(opts ...Option) Registry {