The shim should be started with a single-task VM in this test

Passing a VM ID switches our shim to keep its Firecracker VM.
Starting a container with the same name multiple times doesn't work
under this configuration.

Author: Kazuyoshi Kato

runtime/service.go

@@ -124,7 +124,7 @@ type service struct {
 	agentClient              taskAPI.TaskService
 	eventBridgeClient        eventbridge.Getter
 	stubDriveHandler         stubDriveHandler
-	exitAfterAllTasksDeleted bool
+	exitAfterAllTasksDeleted bool // exit the VM and shim when all tasks are deleted
 
 	machine          *firecracker.Machine
 	machineConfig    *firecracker.Config
@@ -284,7 +284,8 @@ func (s *service) StartShim(shimCtx context.Context, containerID, containerdBina
 
 	logrus.SetOutput(logFifo)
 
-	log.G(shimCtx).WithField("id", containerID).Debug("StartShim")
+	log := log.G(shimCtx).WithField("id", containerID)
+	log.Debug("StartShim")
 
 	// If we are running a shim start routine, we can safely assume our current working
 	// directory is the bundle directory
@@ -319,6 +320,10 @@ func (s *service) StartShim(shimCtx context.Context, containerID, containerdBina
 		// task is deleted
 		containerCount = 1
 		exitAfterAllTasksDeleted = true
+
+		log.Infof("will start a single-task VM %s since no VMID has been provided", s.vmID)
+	} else {
+		log.Infof("will start a persistent VM %s", s.vmID)
 	}
 
 	client, err := ttrpcutil.NewClient(containerdAddress + ".ttrpc")

runtime/service_integ_test.go

@@ -609,7 +609,6 @@ func TestRemoveDir_Isolated(t *testing.T) {
 		containerd.WithNewSnapshot(snapshotName, image),
 		containerd.WithNewSpec(
 			oci.WithProcessArgs("echo", "hello"),
-			firecrackeroci.WithVMID(strconv.Itoa(vmID)),
 		),
 	)
 	require.NoError(t, err, "failed to create container %s", containerName)
@@ -622,7 +621,6 @@ func TestRemoveDir_Isolated(t *testing.T) {
 		containerd.WithNewSnapshot(snapshotName, image),
 		containerd.WithNewSpec(
 			oci.WithProcessArgs("echo", "hello"),
-			firecrackeroci.WithVMID(strconv.Itoa(vmID)),
 		),
 	)
 	require.NoError(t, err, "failed to create container %s", containerName)