Add basic logging to file support

This currently logs to a json file with the stream type.  This is slow
and hard on the cpu and memory so we need to swich this over to
something like protobufs for the binary logs but this is just a start.

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

add_process.go

@@ -1,18 +1,29 @@
 package containerd
 
+import "github.com/Sirupsen/logrus"
+
 type AddProcessEvent struct {
 	s *Supervisor
 }
 
+// TODO: add this to worker for concurrent starts???  maybe not because of races where the container
+// could be stopped and removed...
 func (h *AddProcessEvent) Handle(e *Event) error {
 	container, ok := h.s.containers[e.ID]
 	if !ok {
 		return ErrContainerNotFound
 	}
-	p, err := h.s.runtime.StartProcess(container, *e.Process, e.Stdio)
+	p, io, err := h.s.runtime.StartProcess(container, *e.Process)
 	if err != nil {
 		return err
 	}
+	if err := h.s.log(container.Path(), io); err != nil {
+		// log the error but continue with the other commands
+		logrus.WithFields(logrus.Fields{
+			"error": err,
+			"id":    e.ID,
+		}).Error("log stdio")
+	}
 	if e.Pid, err = p.Pid(); err != nil {
 		return err
 	}