Expose Endpoint IDs in their public interface.

libnetwork/network.go

@@ -77,6 +77,9 @@ type Network interface {
 
 // Endpoint represents a logical connection between a network and a sandbox.
 type Endpoint interface {
+	// A system generated id for this network.
+	ID() string
+
 	// Delete endpoint.
 	Delete() error
 }
@@ -237,6 +240,10 @@ func (n *network) CreateEndpoint(name string, sboxKey string, options interface{
 	return ep, sinfo, nil
 }
 
+func (ep *endpoint) ID() string {
+	return string(ep.id)
+}
+
 func (ep *endpoint) Delete() error {
 	var err error