api: add the ProviderID attribute to NodeSpec

Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>

pkg/cloudprovider/cloud.go

@@ -18,6 +18,7 @@ package cloudprovider
 
 import (
 	"errors"
+	"fmt"
 	"net"
 	"strings"
 
@@ -61,6 +62,18 @@ func GetLoadBalancerName(service *api.Service) string {
 	return ret
 }
 
+func GetInstanceProviderID(cloud Interface, nodeName string) (string, error) {
+	instances, ok := cloud.Instances()
+	if !ok {
+		return "", fmt.Errorf("failed to get instances from cloud provider")
+	}
+	instanceID, err := instances.InstanceID(nodeName)
+	if err != nil {
+		return "", fmt.Errorf("failed to get instance ID from cloud provider: %v", err)
+	}
+	return cloud.ProviderName() + "://" + instanceID, nil
+}
+
 // TCPLoadBalancer is an abstract, pluggable interface for TCP load balancers.
 type TCPLoadBalancer interface {
 	// TODO: Break this up into different interfaces (LB, etc) when we have more than one type of service