fix bug that can't show remote container

Fixes #506

docker service ls can't show container connected remotely, change docker
UI to show "remote" under container ID column for remote container

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

endpoint.go

@@ -456,6 +456,16 @@ func (ep *endpoint) getSandbox() (*sandbox, bool) {
 	ps, ok := c.sandboxes[sid]
 	c.Unlock()
 
+	// if sid isn't empty but ps is nil, that means
+	// sandbox is connected remotely
+	if sid != "" && ps == nil {
+		ps = &sandbox{
+			id:          sid,
+			containerID: remoteCID,
+		}
+		ok = true
+	}
+
 	return ps, ok
 }
 

network.go

@@ -437,7 +437,7 @@ func (n *network) updateSvcRecord(ep *endpoint, isAdd bool) {
 
 	var sbList []*sandbox
 	n.WalkEndpoints(func(e Endpoint) bool {
-		if sb, hasSandbox := e.(*endpoint).getSandbox(); hasSandbox {
+		if sb, hasSandbox := e.(*endpoint).getSandbox(); hasSandbox && !sb.isRemote() {
 			sbList = append(sbList, sb)
 		}
 		return false

sandbox.go

@@ -17,6 +17,10 @@ import (
 	"github.com/docker/libnetwork/types"
 )
 
+const (
+	remoteCID = "remote"
+)
+
 // Sandbox provides the control over the network container entity. It is a one to one mapping with the container.
 type Sandbox interface {
 	// ID returns the ID of the sandbox
@@ -124,6 +128,10 @@ func (sb *sandbox) Labels() map[string]interface{} {
 	return sb.config.generic
 }
 
+func (sb *sandbox) isRemote() bool {
+	return sb.containerID == remoteCID
+}
+
 func (sb *sandbox) Statistics() (map[string]*osl.InterfaceStatistics, error) {
 	m := make(map[string]*osl.InterfaceStatistics)