Integrate poststart hooks with spec

* Call poststart hooks after the container is started
* Tie in with spec configuration

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>

libcontainer/container_linux.go

@@ -183,6 +183,22 @@ func (c *linuxContainer) Start(process *Process) error {
 	if doInit {
 		c.updateState(parent)
 	}
+	if c.config.Hooks != nil {
+		s := configs.HookState{
+			Version: c.config.Version,
+			ID:      c.id,
+			Pid:     parent.pid(),
+			Root:    c.config.Rootfs,
+		}
+		for _, hook := range c.config.Hooks.Poststart {
+			if err := hook.Run(s); err != nil {
+				if err := parent.terminate(); err != nil {
+					logrus.Warn(err)
+				}
+				return newSystemError(err)
+			}
+		}
+	}
 	return nil
 }
 

spec.go

@@ -712,6 +712,14 @@ func createHooks(rspec *specs.LinuxRuntimeSpec, config *configs.Config) {
 		}
 		config.Hooks.Prestart = append(config.Hooks.Prestart, configs.NewCommandHook(cmd))
 	}
+	for _, h := range rspec.Hooks.Poststart {
+		cmd := configs.Command{
+			Path: h.Path,
+			Args: h.Args,
+			Env:  h.Env,
+		}
+		config.Hooks.Poststart = append(config.Hooks.Poststart, configs.NewCommandHook(cmd))
+	}
 	for _, h := range rspec.Hooks.Poststop {
 		cmd := configs.Command{
 			Path: h.Path,