Add initial framework for stats

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

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)
 }