Add initial framework for stats

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

linux/linux.go

@@ -13,6 +13,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/docker/containerd/runtime"
 	"github.com/opencontainers/runc/libcontainer"
@@ -304,6 +305,18 @@ func (c *libcontainerContainer) SetExited(status int) {
 	c.exited = true
 }
 
+func (c *libcontainerContainer) Stats() (*runtime.Stat, error) {
+	now := time.Now()
+	stats, err := c.c.Stats()
+	if err != nil {
+		return nil, err
+	}
+	return &runtime.Stat{
+		Timestamp: now,
+		Data:      stats,
+	}, nil
+}
+
 func (c *libcontainerContainer) Delete() error {
 	return c.c.Destroy()
 }

runc/runc.go

@@ -37,6 +37,10 @@ func (c *runcContainer) Start() error {
 	return c.initProcess.cmd.Start()
 }
 
+func (c *runcContainer) Stats() (*runtime.Stat, error) {
+	return nil, errors.New("containerd: runc does not support stats in containerd")
+}
+
 func (c *runcContainer) Path() string {
 	return c.path
 }

runtime/container.go

@@ -29,6 +29,16 @@ type Stdio struct {
 	Stdout string
 }
 
+type Stat struct {
+	// Timestamp is the time that the statistics where collected
+	Timestamp time.Time
+	// Data is the raw stats
+	// TODO: it is currently an interface because we don't know what type of exec drivers
+	// we will have or what the structure should look like at the moment os the containers
+	// can return what they want and we could marshal to json or whatever.
+	Data interface{}
+}
+
 type Checkpoint struct {
 	// Timestamp is the time that checkpoint happened
 	Timestamp time.Time
@@ -75,4 +85,6 @@ type Container interface {
 	DeleteCheckpoint(name string) error
 	// Restore restores the container to that of the checkpoint provided by name
 	Restore(name string) error
+	// Stats returns realtime container stats and resource information
+	Stats() (*Stat, error)
 }

runtime/runtime.go

@@ -11,10 +11,13 @@ var (
 	ErrInvalidContainerType = errors.New("containerd: invalid container type for runtime")
 	ErrCheckpointNotExists  = errors.New("containerd: checkpoint does not exist for container")
 	ErrCheckpointExists     = errors.New("containerd: checkpoint already exists")
+	ErrContainerExited      = errors.New("containerd: container has exited")
 )
 
-// runtime handles containers, containers handle their own actions.
+// Runtime handles containers, containers handle their own actions
 type Runtime interface {
+	// Create creates a new container initialized but without it starting it
 	Create(id, bundlePath string, stdio *Stdio) (Container, error)
+	// StartProcess adds a new process to the container
 	StartProcess(Container, specs.Process, *Stdio) (Process, error)
 }