Add watch options

registry/options.go

@@ -25,6 +25,15 @@ type RegisterOptions struct {
 	Context context.Context
 }
 
+type WatchOptions struct {
+	// Specify a service to watch
+	// If blank, the watch is for all services
+	Service string
+	// Other options for implementations of the interface
+	// can be stored in a context
+	Context context.Context
+}
+
 // Addrs is the registry addresses to use
 func Addrs(addrs ...string) Option {
 	return func(o *Options) {
@@ -57,3 +66,10 @@ func RegisterTTL(t time.Duration) RegisterOption {
 		o.TTL = t
 	}
 }
+
+// Watch a service
+func WatchService(name string) WatchOption {
+	return func(o *WatchOptions) {
+		o.Service = name
+	}
+}