api: add image's id to ContainerStatus

Sometimes for external applications it is important to identify
exactly what images are running. Since tags can be moved to point
to newer builds this information can be used to identify old images
running.

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

pkg/kubelet/dockertools/docker.go

@@ -41,6 +41,7 @@ import (
 
 const (
 	PodInfraContainerName = leaky.PodInfraContainerName
+	DockerPrefix          = "docker://"
 )
 
 // DockerInterface is an abstract interface for testability.  It abstracts the interface of docker.Client.
@@ -399,7 +400,8 @@ func inspectContainer(client DockerInterface, dockerID, containerName, tPath str
 	glog.V(3).Infof("Container inspect result: %+v", *inspectResult)
 	containerStatus := api.ContainerStatus{
 		Image:       inspectResult.Config.Image,
-		ContainerID: "docker://" + dockerID,
+		ImageID:     DockerPrefix + inspectResult.Image,
+		ContainerID: DockerPrefix + dockerID,
 	}
 
 	waiting := true