registry/mdns: add domain support (#1708)

* registry: add domain options

* registry/mdns: implement domain options

* registry/mdns: return node domain in metadata when querying using wildcard

* Fix nil pointer exception

* registry/mdns: return error from deregister

* registy/mdns: rename tld => domain

registry/options.go

@@ -21,6 +21,8 @@ type RegisterOptions struct {
 	// Other options for implementations of the interface
 	// can be stored in a context
 	Context context.Context
+	// Domain to register the service in
+	Domain string
 }
 
 type WatchOptions struct {
@@ -30,18 +32,26 @@ type WatchOptions struct {
 	// Other options for implementations of the interface
 	// can be stored in a context
 	Context context.Context
+	// Domain to watch
+	Domain string
 }
 
 type DeregisterOptions struct {
 	Context context.Context
+	// Domain the service was registered in
+	Domain string
 }
 
 type GetOptions struct {
 	Context context.Context
+	// Domain to scope the request to
+	Domain string
 }
 
 type ListOptions struct {
 	Context context.Context
+	// Domain to scope the request to
+	Domain string
 }
 
 // Addrs is the registry addresses to use
@@ -83,6 +93,12 @@ func RegisterContext(ctx context.Context) RegisterOption {
 	}
 }
 
+func RegisterDomain(d string) RegisterOption {
+	return func(o *RegisterOptions) {
+		o.Domain = d
+	}
+}
+
 // Watch a service
 func WatchService(name string) WatchOption {
 	return func(o *WatchOptions) {
@@ -96,20 +112,44 @@ func WatchContext(ctx context.Context) WatchOption {
 	}
 }
 
+func WatchDomain(d string) WatchOption {
+	return func(o *WatchOptions) {
+		o.Domain = d
+	}
+}
+
 func DeregisterContext(ctx context.Context) DeregisterOption {
 	return func(o *DeregisterOptions) {
 		o.Context = ctx
 	}
 }
 
+func DeregisterDomain(d string) DeregisterOption {
+	return func(o *DeregisterOptions) {
+		o.Domain = d
+	}
+}
+
 func GetContext(ctx context.Context) GetOption {
 	return func(o *GetOptions) {
 		o.Context = ctx
 	}
 }
 
+func GetDomain(d string) GetOption {
+	return func(o *GetOptions) {
+		o.Domain = d
+	}
+}
+
 func ListContext(ctx context.Context) ListOption {
 	return func(o *ListOptions) {
 		o.Context = ctx
 	}
 }
+
+func ListDomain(d string) ListOption {
+	return func(o *ListOptions) {
+		o.Domain = d
+	}
+}