Add basic checkpoint and restore support

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

api/v1/server.go

@@ -19,17 +19,25 @@ func NewServer(supervisor *containerd.Supervisor) http.Handler {
 		supervisor: supervisor,
 		r:          r,
 	}
-	// TODO: add container stats
+	// process handlers
-	// TODO: add container checkpoint
-	// TODO: add container restore
-	// TODO: set prctl child subreaper
 	r.HandleFunc("/containers/{id:.*}/process/{pid:.*}", s.signalPid).Methods("POST")
 	r.HandleFunc("/containers/{id:.*}/process", s.addProcess).Methods("PUT")
+
+	// checkpoint and restore handlers
+	// TODO: PUT handler for adding a checkpoint to containerd??
+	r.HandleFunc("/containers/{id:.*}/checkpoint/{name:.*}", s.createCheckpoint).Methods("POST")
+	// r.HandleFunc("/containers/{id:.*}/checkpoint/{cid:.*}", s.deleteCheckpoint).Methods("DELETE")
+	r.HandleFunc("/containers/{id:.*}/checkpoint", s.listCheckpoints).Methods("GET")
+
+	// container handlers
 	r.HandleFunc("/containers/{id:.*}", s.createContainer).Methods("POST")
 	r.HandleFunc("/containers/{id:.*}", s.updateContainer).Methods("PATCH")
+
 	// internal method for replaying the journal
 	r.HandleFunc("/event", s.event).Methods("POST")
 	r.HandleFunc("/events", s.events).Methods("GET")
+
+	// containerd handlers
 	r.HandleFunc("/state", s.state).Methods("GET")
 	return s
 }
@@ -252,6 +260,12 @@ func (s *server) createContainer(w http.ResponseWriter, r *http.Request) {
 	e := containerd.NewEvent(containerd.StartContainerEventType)
 	e.ID = id
 	e.BundlePath = c.BundlePath
+	if c.Checkpoint != nil {
+		e.Checkpoint = &runtime.Checkpoint{
+			Name: c.Checkpoint.Name,
+			Path: c.Checkpoint.Path,
+		}
+	}
 	e.Stdio = &runtime.Stdio{
 		Stderr: c.Stderr,
 		Stdout: c.Stdout,
@@ -267,3 +281,71 @@ func (s *server) createContainer(w http.ResponseWriter, r *http.Request) {
 	}
 	w.WriteHeader(http.StatusCreated)
 }
+
+func (s *server) listCheckpoints(w http.ResponseWriter, r *http.Request) {
+	id := mux.Vars(r)["id"]
+	e := containerd.NewEvent(containerd.GetContainerEventType)
+	s.supervisor.SendEvent(e)
+	if err := <-e.Err; err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	var container runtime.Container
+	for _, c := range e.Containers {
+		if c.ID() == id {
+			container = c
+			break
+		}
+	}
+	if container == nil {
+		http.Error(w, "container not found", http.StatusNotFound)
+		return
+	}
+	checkpoints, err := container.Checkpoints()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	out := []Checkpoint{}
+	for _, c := range checkpoints {
+		out = append(out, Checkpoint{
+			Path:        c.Path,
+			Name:        c.Name,
+			Tcp:         c.Tcp,
+			Shell:       c.Shell,
+			UnixSockets: c.UnixSockets,
+		})
+	}
+}
+
+func (s *server) createCheckpoint(w http.ResponseWriter, r *http.Request) {
+	var (
+		vars = mux.Vars(r)
+		id   = vars["id"]
+		name = vars["name"]
+	)
+	var cp Checkpoint
+	if err := json.NewDecoder(r.Body).Decode(&cp); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	e := containerd.NewEvent(containerd.CreateCheckpointEventType)
+	e.ID = id
+	e.Checkpoint = &runtime.Checkpoint{
+		Name:        name,
+		Path:        cp.Path,
+		Running:     cp.Running,
+		Tcp:         cp.Tcp,
+		UnixSockets: cp.UnixSockets,
+		Shell:       cp.Shell,
+	}
+	s.supervisor.SendEvent(e)
+	if err := <-e.Err; err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.WriteHeader(http.StatusCreated)
+}
+
+func (s *server) deleteCheckpoint(w http.ResponseWriter, r *http.Request) {
+}

api/v1/types.go

@@ -28,6 +28,7 @@ type Container struct {
 	Stdout     string          `json:"stdout,omitempty"`
 	Stderr     string          `json:"stderr,omitempty"`
 	State      *ContainerState `json:"state,omitempty"`
+	Checkpoint *Checkpoint     `json:"checkpoint,omitempty"`
 }
 
 type User struct {
@@ -54,3 +55,12 @@ type Event struct {
 	ID     string `json:"id,omitempty"`
 	Status int    `json:"status,omitempty"`
 }
+
+type Checkpoint struct {
+	Name        string `json:"name,omitempty"`
+	Path        string `json:"path"`
+	Running     bool   `json:"running,omitempty"`
+	Tcp         bool   `json:"tcp"`
+	UnixSockets bool   `json:"unixSockets"`
+	Shell       bool   `json:"shell"`
+}

checkpoint.go

@@ -0,0 +1,13 @@
+package containerd
+
+type CreateCheckpointEvent struct {
+	s *Supervisor
+}
+
+func (h *CreateCheckpointEvent) Handle(e *Event) error {
+	container, ok := h.s.containers[e.ID]
+	if !ok {
+		return ErrContainerNotFound
+	}
+	return container.Checkpoint(*e.Checkpoint)
+}

event.go

@@ -19,6 +19,7 @@ const (
 	SignalEventType           EventType = "signal"
 	AddProcessEventType       EventType = "addProcess"
 	UpdateContainerEventType  EventType = "updateContainer"
+	CreateCheckpointEventType EventType = "createCheckpoint"
 )
 
 func NewEvent(t EventType) *Event {
@@ -41,6 +42,7 @@ type Event struct {
 	Process    *specs.Process      `json:"process,omitempty"`
 	State      *runtime.State      `json:"state,omitempty"`
 	Containers []runtime.Container `json:"-"`
+	Checkpoint *runtime.Checkpoint `json:"checkpoint,omitempty"`
 	Err        chan error          `json:"-"`
 }
 

linux/linux.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/docker/containerd/runtime"
 	"github.com/opencontainers/runc/libcontainer"
@@ -190,6 +191,57 @@ type libcontainerContainer struct {
 	exitStatus          int
 	exited              bool
 	path                string
+	checkpoints         map[string]runtime.Checkpoint
+}
+
+func (c *libcontainerContainer) Checkpoints() ([]runtime.Checkpoint, error) {
+	out := []runtime.Checkpoint{}
+	for _, cp := range c.checkpoints {
+		out = append(out, cp)
+	}
+	return out, nil
+}
+
+func (c *libcontainerContainer) Checkpoint(cp runtime.Checkpoint) error {
+	opts := c.createCheckpointOpts(&cp)
+	if err := os.MkdirAll(opts.ImagesDirectory, 0755); err != nil {
+		return err
+	}
+	if err := c.c.Checkpoint(opts); err != nil {
+		return err
+	}
+	cp.Timestamp = time.Now()
+	c.checkpoints[cp.Name] = cp
+	return nil
+}
+
+func (c *libcontainerContainer) createCheckpointOpts(cp *runtime.Checkpoint) *libcontainer.CriuOpts {
+	opts := libcontainer.CriuOpts{}
+	opts.LeaveRunning = cp.Running
+	opts.ShellJob = cp.Shell
+	opts.TcpEstablished = cp.Tcp
+	opts.ExternalUnixConnections = cp.UnixSockets
+	if cp.Path == "" {
+		cp.Path = filepath.Join(c.path, "checkpoints", cp.Name)
+	}
+	opts.ImagesDirectory = cp.Path
+	return &opts
+}
+
+func (c *libcontainerContainer) Restore(path, name string) error {
+	if path == "" {
+		path = filepath.Join(c.path, "checkpoints", name)
+	}
+	var opts libcontainer.CriuOpts
+	if cp, ok := c.checkpoints[name]; ok {
+		opts = *c.createCheckpointOpts(&cp)
+	} else {
+		opts.ImagesDirectory = path
+	}
+	if err := c.c.Restore(c.initProcess.process, &opts); err != nil {
+		return err
+	}
+	return nil
 }
 
 func (c *libcontainerContainer) Resume() error {
@@ -300,6 +352,7 @@ func (r *libcontainerRuntime) Create(id, bundlePath string, stdio *runtime.Stdio
 	c := &libcontainerContainer{
 		c:                   container,
 		additionalProcesses: make(map[int]*libcontainerProcess),
+		checkpoints:         make(map[string]runtime.Checkpoint),
 		initProcess: &libcontainerProcess{
 			process: process,
 			spec:    spec.Process,

runtime/container.go

@@ -2,6 +2,7 @@ package runtime
 
 import (
 	"os"
+	"time"
 
 	"github.com/opencontainers/specs"
 )
@@ -11,6 +12,7 @@ type Process interface {
 	Spec() specs.Process
 	Signal(os.Signal) error
 }
+
 type Status string
 
 const (
@@ -27,6 +29,16 @@ type Stdio struct {
 	Stdout string `json:"stdout,omitempty"`
 }
 
+type Checkpoint struct {
+	Timestamp   time.Time `json:"timestamp,omitempty"`
+	Path        string    `json:"path,omitempty"`
+	Name        string    `json:"name,omitempty"`
+	Tcp         bool      `json:"tcp"`
+	UnixSockets bool      `json:"unixSockets"`
+	Shell       bool      `json:"shell"`
+	Running     bool      `json:"running,omitempty"`
+}
+
 type Container interface {
 	// ID returns the container ID
 	ID() string
@@ -50,4 +62,10 @@ type Container interface {
 	Resume() error
 	// Pause pauses a running container
 	Pause() error
+
+	Checkpoints() ([]Checkpoint, error)
+
+	Checkpoint(Checkpoint) error
+
+	Restore(path, name string) error
 }

start.go

@@ -11,9 +11,16 @@ func (h *StartEvent) Handle(e *Event) error {
 	}
 	h.s.containers[e.ID] = container
 	ContainersCounter.Inc(1)
-	h.s.tasks <- &StartTask{
+	task := &StartTask{
 		Err:       e.Err,
 		Container: container,
 	}
+	if e.Checkpoint != nil {
+		task.Checkpoint = &Checkpoint{
+			Name: e.Checkpoint.Name,
+			Path: e.Checkpoint.Path,
+		}
+	}
+	h.s.tasks <- task
 	return errDeferedResponse
 }

supervisor.go

@@ -48,6 +48,7 @@ func NewSupervisor(stateDir string, tasks chan *StartTask) (*Supervisor, error)
 		SignalEventType:           &SignalEvent{s},
 		AddProcessEventType:       &AddProcessEvent{s},
 		UpdateContainerEventType:  &UpdateEvent{s},
+		CreateCheckpointEventType: &CreateCheckpointEvent{s},
 	}
 	// start the container workers for concurrent container starts
 	return s, nil

worker.go

@@ -11,8 +11,14 @@ type Worker interface {
 	Start()
 }
 
+type Checkpoint struct {
+	Path string
+	Name string
+}
+
 type StartTask struct {
 	Container  runtime.Container
+	Checkpoint *Checkpoint
 	Err        chan error
 }
 
@@ -32,6 +38,15 @@ func (w *worker) Start() {
 	defer w.wg.Done()
 	for t := range w.s.tasks {
 		started := time.Now()
+		if t.Checkpoint != nil {
+			if err := t.Container.Restore(t.Checkpoint.Path, t.Checkpoint.Name); err != nil {
+				evt := NewEvent(DeleteEventType)
+				evt.ID = t.Container.ID()
+				w.s.SendEvent(evt)
+				t.Err <- err
+				continue
+			}
+		} else {
 			if err := t.Container.Start(); err != nil {
 				evt := NewEvent(DeleteEventType)
 				evt.ID = t.Container.ID()
@@ -39,6 +54,7 @@ func (w *worker) Start() {
 				t.Err <- err
 				continue
 			}
+		}
 		ContainerStartTimer.UpdateSince(started)
 		t.Err <- nil
 	}