add InstanceID to fake cadvisor (used in Kubemark)

pkg/kubelet/cadvisor/testing/cadvisor_fake.go

@@ -25,6 +25,7 @@ import (
 
 // Fake cAdvisor implementation.
 type Fake struct {
+	NodeName string
 }
 
 var _ cadvisor.Interface = new(Fake)
@@ -54,6 +55,7 @@ func (c *Fake) MachineInfo() (*cadvisorapi.MachineInfo, error) {
 	// We set it to non-zero values to make non-zero-capacity machines in Kubemark.
 	return &cadvisorapi.MachineInfo{
 		NumCores:       1,
+		InstanceID:     cadvisorapi.InstanceID(c.NodeName),
 		MemoryCapacity: 4026531840,
 	}, nil
 }