Add journaling

api/v1/server.go

@@ -49,12 +49,11 @@ func (s *server) signalPid(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
-	e := &containerd.SignalEvent{
-		ID:     id,
-		Pid:    pid,
-		Signal: syscall.Signal(signal.Signal),
-		Err:    make(chan error, 1),
-	}
+
+	e := containerd.NewEvent(containerd.SignalEventType)
+	e.ID = id
+	e.Pid = pid
+	e.Signal = syscall.Signal(signal.Signal)
 	s.supervisor.SendEvent(e)
 	if err := <-e.Err; err != nil {
 		status := http.StatusInternalServerError
@@ -69,9 +68,7 @@ func (s *server) signalPid(w http.ResponseWriter, r *http.Request) {
 func (s *server) containers(w http.ResponseWriter, r *http.Request) {
 	var state State
 	state.Containers = []Container{}
-	e := &containerd.GetContainersEvent{
-		Err: make(chan error, 1),
-	}
+	e := containerd.NewEvent(containerd.GetContainerEventType)
 	s.supervisor.SendEvent(e)
 	if err := <-e.Err; err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
@@ -112,11 +109,9 @@ func (s *server) createContainer(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "empty bundle path", http.StatusBadRequest)
 		return
 	}
-	e := &containerd.StartContainerEvent{
-		ID:         id,
-		BundlePath: c.BundlePath,
-		Err:        make(chan error, 1),
-	}
+	e := containerd.NewEvent(containerd.StartContainerEventType)
+	e.ID = id
+	e.BundlePath = c.BundlePath
 	s.supervisor.SendEvent(e)
 	if err := <-e.Err; err != nil {
 		code := http.StatusInternalServerError

containerd/daemon.go

@@ -54,7 +54,7 @@ func daemon(stateDir string, concurrency, bufferSize int) error {
 	if err != nil {
 		return err
 	}
-	events := make(chan containerd.Event, bufferSize)
+	events := make(chan *containerd.Event, bufferSize)
 	// start the signal handler in the background.
 	go startSignalHandler(supervisor, bufferSize)
 	if err := supervisor.Start(events); err != nil {
@@ -71,6 +71,7 @@ func startSignalHandler(supervisor *containerd.Supervisor, bufferSize int) {
 	for s := range signals {
 		switch s {
 		case syscall.SIGTERM, syscall.SIGINT, syscall.SIGSTOP:
+			supervisor.Close()
 			os.Exit(0)
 		case syscall.SIGCHLD:
 			exits, err := reap()
@@ -84,7 +85,7 @@ func startSignalHandler(supervisor *containerd.Supervisor, bufferSize int) {
 	}
 }
 
-func reap() (exits []*containerd.ExitEvent, err error) {
+func reap() (exits []*containerd.Event, err error) {
 	var (
 		ws  syscall.WaitStatus
 		rus syscall.Rusage
@@ -100,9 +101,9 @@ func reap() (exits []*containerd.ExitEvent, err error) {
 		if pid <= 0 {
 			return exits, nil
 		}
-		exits = append(exits, &containerd.ExitEvent{
-			Pid:    pid,
-			Status: utils.ExitStatus(ws),
-		})
+		e := containerd.NewEvent(containerd.ExitEventType)
+		e.Pid = pid
+		e.Status = utils.ExitStatus(ws)
+		exits = append(exits, e)
 	}
 }

event.go

@@ -1,59 +1,36 @@
 package containerd
 
-import "os"
+import (
+	"os"
+	"time"
+)
 
-type Event interface {
-	String() string
+type EventType string
+
+const (
+	ExitEventType                EventType = "exit"
+	StartContainerEventType      EventType = "startContainer"
+	ContainerStartErrorEventType EventType = "startContainerError"
+	GetContainerEventType        EventType = "getContainer"
+	SignalEventType              EventType = "signal"
+)
+
+func NewEvent(t EventType) *Event {
+	return &Event{
+		Type:      t,
+		Timestamp: time.Now(),
+		Err:       make(chan error, 1),
+	}
 }
 
-type CallbackEvent interface {
-	Event() Event
-	Callback() chan Event
-}
-
-type ExitEvent struct {
-	Pid    int
-	Status int
-}
-
-func (e *ExitEvent) String() string {
-	return "exit event"
-}
-
-type StartContainerEvent struct {
-	ID         string
-	BundlePath string
-	Err        chan error
-}
-
-func (c *StartContainerEvent) String() string {
-	return "create container"
-}
-
-type ContainerStartErrorEvent struct {
-	ID string
-}
-
-func (c *ContainerStartErrorEvent) String() string {
-	return "container start error"
-}
-
-type GetContainersEvent struct {
-	Containers []Container
-	Err        chan error
-}
-
-func (c *GetContainersEvent) String() string {
-	return "get containers"
-}
-
-type SignalEvent struct {
-	ID     string
-	Pid    int
-	Signal os.Signal
-	Err    chan error
-}
-
-func (s *SignalEvent) String() string {
-	return "signal event"
+type Event struct {
+	Type       EventType   `json:"type"`
+	Timestamp  time.Time   `json:"timestamp"`
+	ID         string      `json:"id,omitempty"`
+	BundlePath string      `json:"bundlePath,omitempty"`
+	Pid        int         `json:"pid,omitempty"`
+	Status     int         `json:"status,omitempty"`
+	Signal     os.Signal   `json:"signal,omitempty"`
+	Containers []Container `json:"-"`
+	Err        chan error  `json:"-"`
 }

journal.go

@@ -0,0 +1,41 @@
+package containerd
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+)
+
+type entry struct {
+	Event *Event `json:"event"`
+}
+
+func newJournal(path string) (*journal, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return nil, err
+	}
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0755)
+	if err != nil {
+		return nil, err
+	}
+	return &journal{
+		f:   f,
+		enc: json.NewEncoder(f),
+	}, nil
+}
+
+type journal struct {
+	f   *os.File
+	enc *json.Encoder
+}
+
+func (j *journal) write(e *Event) error {
+	et := &entry{
+		Event: e,
+	}
+	return j.enc.Encode(et)
+}
+
+func (j *journal) Close() error {
+	return j.f.Close()
+}

supervisor.go

@@ -2,6 +2,7 @@ package containerd
 
 import (
 	"os"
+	"path/filepath"
 	"sync"
 
 	"github.com/Sirupsen/logrus"
@@ -18,11 +19,16 @@ func NewSupervisor(stateDir string, concurrency int) (*Supervisor, error) {
 	if err != nil {
 		return nil, err
 	}
+	j, err := newJournal(filepath.Join(stateDir, "journal.json"))
+	if err != nil {
+		return nil, err
+	}
 	s := &Supervisor{
 		stateDir:   stateDir,
 		containers: make(map[string]Container),
 		runtime:    runtime,
 		tasks:      make(chan *startTask, concurrency*100),
+		journal:    j,
 	}
 	for i := 0; i < concurrency; i++ {
 		s.workerGroup.Add(1)
@@ -39,24 +45,33 @@ type Supervisor struct {
 
 	runtime Runtime
 
-	events      chan Event
+	journal *journal
+
+	events      chan *Event
 	tasks       chan *startTask
 	workerGroup sync.WaitGroup
 }
 
+func (s *Supervisor) Close() error {
+	return s.journal.Close()
+}
+
 // Start is a non-blocking call that runs the supervisor for monitoring contianer processes and
 // executing new containers.
 //
 // This event loop is the only thing that is allowed to modify state of containers and processes.
-func (s *Supervisor) Start(events chan Event) error {
+func (s *Supervisor) Start(events chan *Event) error {
 	if events == nil {
 		return ErrEventChanNil
 	}
 	s.events = events
 	go func() {
-		for evt := range events {
-			switch e := evt.(type) {
-			case *ExitEvent:
+		for e := range events {
+			if err := s.journal.write(e); err != nil {
+				logrus.WithField("error", err).Error("write journal entry")
+			}
+			switch e.Type {
+			case ExitEventType:
 				logrus.WithFields(logrus.Fields{"pid": e.Pid, "status": e.Status}).
 					Debug("containerd: process exited")
 				container, err := s.getContainerForPid(e.Pid)
@@ -70,7 +85,7 @@ func (s *Supervisor) Start(events chan Event) error {
 				if err := s.deleteContainer(container); err != nil {
 					logrus.WithField("error", err).Error("containerd: deleting container")
 				}
-			case *StartContainerEvent:
+			case StartContainerEventType:
 				container, err := s.runtime.Create(e.ID, e.BundlePath)
 				if err != nil {
 					e.Err <- err
@@ -81,18 +96,18 @@ func (s *Supervisor) Start(events chan Event) error {
 					err:       e.Err,
 					container: container,
 				}
-			case *ContainerStartErrorEvent:
+			case ContainerStartErrorEventType:
 				if container, ok := s.containers[e.ID]; ok {
 					if err := s.deleteContainer(container); err != nil {
 						logrus.WithField("error", err).Error("containerd: deleting container")
 					}
 				}
-			case *GetContainersEvent:
+			case GetContainerEventType:
 				for _, c := range s.containers {
 					e.Containers = append(e.Containers, c)
 				}
 				e.Err <- nil
-			case *SignalEvent:
+			case SignalEventType:
 				container, ok := s.containers[e.ID]
 				if !ok {
 					e.Err <- ErrContainerNotFound
@@ -139,7 +154,7 @@ func (s *Supervisor) getContainerForPid(pid int) (Container, error) {
 	return nil, errNoContainerForPid
 }
 
-func (s *Supervisor) SendEvent(evt Event) {
+func (s *Supervisor) SendEvent(evt *Event) {
 	s.events <- evt
 }
 
@@ -152,9 +167,9 @@ func (s *Supervisor) startContainerWorker(tasks chan *startTask) {
 	defer s.workerGroup.Done()
 	for t := range tasks {
 		if err := t.container.Start(); err != nil {
-			s.SendEvent(&ContainerStartErrorEvent{
-				ID: t.container.ID(),
-			})
+			e := NewEvent(StartContainerEventType)
+			e.ID = t.container.ID()
+			s.SendEvent(e)
 			t.err <- err
 			continue
 		}