Restore implementation added to runsc.

Restore creates a new container and uses the given image-path to load a saved
image of a previous container. Restore command is plumbed through container
and sandbox. This command does not work yet - more to come.

PiperOrigin-RevId: 201541229
Change-Id: I864a14c799ce3717d99bcdaaebc764281863d06f

2 files changed, 23 insertions, 5 deletions

diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go
index 652910efa..870a0ccd3 100644
--- a/runsc/sandbox/sandbox.go
+++ b/runsc/sandbox/sandbox.go
@@ -54,7 +54,9 @@ type Sandbox struct {
 }
 
 // Create creates the sandbox process.
-func Create(id string, spec *specs.Spec, conf *boot.Config, bundleDir, consoleSocket string) (*Sandbox, error) {
+//
+// If restoreFile is not empty, the sandbox will be restored from file.
+func Create(id string, spec *specs.Spec, conf *boot.Config, bundleDir, consoleSocket string, restoreFile string) (*Sandbox, error) {
 	s := &Sandbox{ID: id}
 
 	binPath, err := specutils.BinPath()
@@ -69,7 +71,7 @@ func Create(id string, spec *specs.Spec, conf *boot.Config, bundleDir, consoleSo
 	}
 
 	// Create the sandbox process.
-	if err := s.createSandboxProcess(spec, conf, bundleDir, consoleSocket, binPath, ioFiles); err != nil {
+	if err := s.createSandboxProcess(spec, conf, bundleDir, consoleSocket, binPath, ioFiles, restoreFile); err != nil {
 		return nil, err
 	}
 
@@ -251,7 +253,7 @@ func (s *Sandbox) createGoferProcess(spec *specs.Spec, conf *boot.Config, bundle
 
 // createSandboxProcess starts the sandbox as a subprocess by running the "boot"
 // command, passing in the bundle dir.
-func (s *Sandbox) createSandboxProcess(spec *specs.Spec, conf *boot.Config, bundleDir, consoleSocket, binPath string, ioFiles []*os.File) error {
+func (s *Sandbox) createSandboxProcess(spec *specs.Spec, conf *boot.Config, bundleDir, consoleSocket, binPath string, ioFiles []*os.File, restoreFile string) error {
 	// nextFD is used to get unused FDs that we can pass to the sandbox.  It
 	// starts at 3 because 0, 1, and 2 are taken by stdin/out/err.
 	nextFD := 3
@@ -273,12 +275,27 @@ func (s *Sandbox) createSandboxProcess(spec *specs.Spec, conf *boot.Config, bund
 		"--bundle", bundleDir,
 		"--controller-fd="+strconv.Itoa(nextFD),
 		fmt.Sprintf("--console=%t", consoleEnabled))
-	nextFD++
 
 	controllerFile := os.NewFile(uintptr(fd), "control_server_socket")
 	defer controllerFile.Close()
 	cmd.ExtraFiles = append(cmd.ExtraFiles, controllerFile)
 
+	// If a restore filename was given, open the file and append its FD to Args
+	// and the file to ExtraFiles.
+	if restoreFile != "" {
+		// Create the image file and open for reading.
+		rF, err := os.Open(restoreFile)
+		if err != nil {
+			return fmt.Errorf("os.Open(%q) failed: %v", restoreFile, err)
+		}
+		defer rF.Close()
+
+		nextFD++
+		cmd.Args = append(cmd.Args, "--restore-fd="+strconv.Itoa(nextFD))
+		cmd.ExtraFiles = append(cmd.ExtraFiles, rF)
+	}
+	nextFD++
+
 	// If there is a gofer, sends all socket ends to the sandbox.
 	for _, f := range ioFiles {
 		defer f.Close()
@@ -379,6 +396,7 @@ func (s *Sandbox) createSandboxProcess(spec *specs.Spec, conf *boot.Config, bund
 	}
 	s.Pid = cmd.Process.Pid
 	log.Infof("Sandbox started, pid: %d", s.Pid)
+
 	return nil
 }
 
diff --git a/runsc/sandbox/sandbox_test.go b/runsc/sandbox/sandbox_test.go
index fee2de283..9db90ef07 100644
--- a/runsc/sandbox/sandbox_test.go
+++ b/runsc/sandbox/sandbox_test.go
@@ -39,7 +39,7 @@ func TestGoferExits(t *testing.T) {
 	defer os.RemoveAll(bundleDir)
 
 	// Create, start and wait for the container.
-	s, err := Create(testutil.UniqueContainerID(), spec, conf, bundleDir, "")
+	s, err := Create(testutil.UniqueContainerID(), spec, conf, bundleDir, "", "")
 	if err != nil {
 		t.Fatalf("error creating container: %v", err)
 	}