VOL-381 add unum container to support ONOS cluster formation under swarm

Change-Id: Ic260edda19bb199ed040f05164ab605f28c919d0
diff --git a/unum/orchestration.go b/unum/orchestration.go
new file mode 100644
index 0000000..b44c85f
--- /dev/null
+++ b/unum/orchestration.go
@@ -0,0 +1,51 @@
+// Copyright 2017 the original author or authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"net/url"
+)
+
+type ClusterInfo struct {
+	Expected uint64
+	Nodes    []string
+}
+
+type OrchestrationClient interface {
+	Init(url *url.URL) error
+	GetInfo(labels map[string]string, networkLabels map[string]string) (*ClusterInfo, error)
+	Close() error
+}
+
+func NewOrchestrationClient(url *url.URL) (OrchestrationClient, error) {
+	var client OrchestrationClient
+
+	switch url.Scheme {
+	case "swarm":
+		client = &SwarmClient{}
+	case "kubernetes":
+		return nil, fmt.Errorf("Kubernetes is not yet supported")
+	default:
+		return nil, fmt.Errorf("Unknown container orchestrator, '%s' specified",
+			url.Scheme)
+	}
+
+	err := client.Init(url)
+	if err != nil {
+		return nil, err
+	}
+	return client, nil
+}