sandbox: Create and export Pause/ResumeContainer() 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 functions
PauseContainer() and ResumeContainer(), 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

@@ -784,17 +784,11 @@ func togglePauseContainer(ctx context.Context, sandboxID, containerID string, pa
 	}
 	defer s.releaseStatelessSandbox()
 
-	// Fetch the container.
-	c, err := s.findContainer(containerID)
-	if err != nil {
-		return err
-	}
-
 	if pause {
-		return c.pause()
+		return s.PauseContainer(containerID)
 	}
 
-	return c.resume()
+	return s.ResumeContainer(containerID)
 }
 
 // PauseContainer is the virtcontainers container pause entry point.

virtcontainers/interfaces.go

@@ -81,6 +81,8 @@ type VCSandbox interface {
 	KillContainer(containerID string, signal syscall.Signal, all bool) error
 	StatusContainer(containerID string) (ContainerStatus, error)
 	StatsContainer(containerID string) (ContainerStats, error)
+	PauseContainer(containerID string) error
+	ResumeContainer(containerID string) error
 	EnterContainer(containerID string, cmd Cmd) (VCContainer, *Process, error)
 	UpdateContainer(containerID string, resources specs.LinuxResources) error
 	ProcessListContainer(containerID string, options ProcessListOptions) (ProcessList, error)

virtcontainers/pkg/vcmock/sandbox.go

@@ -127,6 +127,16 @@ func (s *Sandbox) StatsContainer(contID string) (vc.ContainerStats, error) {
 	return vc.ContainerStats{}, nil
 }
 
+// PauseContainer implements the VCSandbox function of the same name.
+func (s *Sandbox) PauseContainer(contID string) error {
+	return nil
+}
+
+// ResumeContainer implements the VCSandbox function of the same name.
+func (s *Sandbox) ResumeContainer(contID string) error {
+	return nil
+}
+
 // Status implements the VCSandbox function of the same name.
 func (s *Sandbox) Status() vc.SandboxStatus {
 	return vc.SandboxStatus{}

virtcontainers/sandbox.go

@@ -1463,6 +1463,30 @@ func (s *Sandbox) StatsContainer(containerID string) (ContainerStats, error) {
 	return *stats, nil
 }
 
+// PauseContainer pauses a running container.
+func (s *Sandbox) PauseContainer(containerID string) error {
+	// Fetch the container.
+	c, err := s.findContainer(containerID)
+	if err != nil {
+		return err
+	}
+
+	// Pause the container.
+	return c.pause()
+}
+
+// ResumeContainer resumes a paused container.
+func (s *Sandbox) ResumeContainer(containerID string) error {
+	// Fetch the container.
+	c, err := s.findContainer(containerID)
+	if err != nil {
+		return err
+	}
+
+	// Resume the container.
+	return c.resume()
+}
+
 // createContainers registers all containers to the proxy, create the
 // containers in the guest and starts one shim per container.
 func (s *Sandbox) createContainers() error {