sandbox: Create and export StopContainer() to the API level

In order to support use cases such as containerd-shim-v2 where we
would have a long running process holding the sandbox pointer, there
would be no reason to call into the stateless function StopContainer(),
which would recreate a new sandbox pointer and the corresponding ones
for containers.

Fixes #903

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

virtcontainers/api.go

@@ -502,19 +502,7 @@ func StopContainer(ctx context.Context, sandboxID, containerID string) (VCContai
 	}
 	defer s.releaseStatelessSandbox()
 
-	// Fetch the container.
-	c, err := s.findContainer(containerID)
-	if err != nil {
-		return nil, err
-	}
-
-	// Stop it.
-	err = c.stop()
-	if err != nil {
-		return nil, err
-	}
-
-	return c, nil
+	return s.StopContainer(containerID)
 }
 
 // EnterContainer is the virtcontainers container command execution entry point.

virtcontainers/interfaces.go

@@ -77,6 +77,7 @@ type VCSandbox interface {
 	CreateContainer(contConfig ContainerConfig) (VCContainer, error)
 	DeleteContainer(contID string) (VCContainer, error)
 	StartContainer(containerID string) (VCContainer, error)
+	StopContainer(containerID string) (VCContainer, error)
 	StatusContainer(containerID string) (ContainerStatus, error)
 	StatsContainer(containerID string) (ContainerStats, error)
 	EnterContainer(containerID string, cmd Cmd) (VCContainer, *Process, error)

virtcontainers/pkg/vcmock/sandbox.go

@@ -107,6 +107,11 @@ func (s *Sandbox) StartContainer(contID string) (vc.VCContainer, error) {
 	return &Container{}, nil
 }
 
+// StopContainer implements the VCSandbox function of the same name.
+func (s *Sandbox) StopContainer(contID string) (vc.VCContainer, error) {
+	return &Container{}, nil
+}
+
 // StatusContainer implements the VCSandbox function of the same name.
 func (s *Sandbox) StatusContainer(contID string) (vc.ContainerStatus, error) {
 	return vc.ContainerStatus{}, nil

virtcontainers/sandbox.go

@@ -1320,6 +1320,22 @@ func (s *Sandbox) StartContainer(containerID string) (VCContainer, error) {
 	return c, nil
 }
 
+// StopContainer stops a container in the sandbox
+func (s *Sandbox) StopContainer(containerID string) (VCContainer, error) {
+	// Fetch the container.
+	c, err := s.findContainer(containerID)
+	if err != nil {
+		return nil, err
+	}
+
+	// Stop it.
+	if err := c.stop(); err != nil {
+		return nil, err
+	}
+
+	return c, nil
+}
+
 // DeleteContainer deletes a container from the sandbox
 func (s *Sandbox) DeleteContainer(containerID string) (VCContainer, error) {
 	if containerID == "" {