sandbox: Create and export ProcessListContainer() 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
ProcessListContainer(), 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

@@ -702,13 +702,7 @@ func ProcessListContainer(ctx context.Context, sandboxID, containerID string, op
 	}
 	defer s.releaseStatelessSandbox()
 
-	// Fetch the container.
+	return s.ProcessListContainer(containerID, options)
-	c, err := s.findContainer(containerID)
-	if err != nil {
-		return nil, err
-	}
-
-	return c.processList(options)
 }
 
 // UpdateContainer is the virtcontainers entry point to update

virtcontainers/interfaces.go

@@ -83,6 +83,7 @@ type VCSandbox interface {
 	StatsContainer(containerID string) (ContainerStats, error)
 	EnterContainer(containerID string, cmd Cmd) (VCContainer, *Process, error)
 	UpdateContainer(containerID string, resources specs.LinuxResources) error
+	ProcessListContainer(containerID string, options ProcessListOptions) (ProcessList, error)
 	WaitProcess(containerID, processID string) (int32, error)
 	SignalProcess(containerID, processID string, signal syscall.Signal, all bool) error
 	WinsizeProcess(containerID, processID string, height, width uint32) error

virtcontainers/pkg/vcmock/sandbox.go

@@ -147,6 +147,11 @@ func (s *Sandbox) UpdateContainer(containerID string, resources specs.LinuxResou
 	return nil
 }
 
+// ProcessListContainer implements the VCSandbox function of the same name.
+func (s *Sandbox) ProcessListContainer(containerID string, options vc.ProcessListOptions) (vc.ProcessList, error) {
+	return nil, nil
+}
+
 // WaitProcess implements the VCSandbox function of the same name.
 func (s *Sandbox) WaitProcess(containerID, processID string) (int32, error) {
 	return 0, nil

virtcontainers/sandbox.go

@@ -1383,6 +1383,19 @@ func (s *Sandbox) DeleteContainer(containerID string) (VCContainer, error) {
 	return c, nil
 }
 
+// ProcessListContainer lists every process running inside a specific
+// container in the sandbox.
+func (s *Sandbox) ProcessListContainer(containerID string, options ProcessListOptions) (ProcessList, error) {
+	// Fetch the container.
+	c, err := s.findContainer(containerID)
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the process list related to the container.
+	return c.processList(options)
+}
+
 // StatusContainer gets the status of a container
 // TODO: update container status properly, see kata-containers/runtime#253
 func (s *Sandbox) StatusContainer(containerID string) (ContainerStatus, error) {