Fix nsinit function to get stats from systemd

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

api_temp.go

@@ -5,24 +5,30 @@ package libcontainer
 
 import (
 	"github.com/docker/libcontainer/cgroups/fs"
+	"github.com/docker/libcontainer/cgroups/systemd"
 	"github.com/docker/libcontainer/network"
 )
 
 // TODO(vmarmol): Complete Stats() in final libcontainer API and move users to that.
 // DEPRECATED: The below portions are only to be used during the transition to the official API.
 // Returns all available stats for the given container.
 func GetStats(container *Config, state *State) (*ContainerStats, error) {
-	var containerStats ContainerStats
-	stats, err := fs.GetStats(container.Cgroups)
-	if err != nil {
-		return &containerStats, err
+	var (
+		err   error
+		stats = &ContainerStats{}
+	)
+
+	if systemd.UseSystemd() {
+		stats.CgroupStats, err = systemd.GetStats(container.Cgroups)
+	} else {
+		stats.CgroupStats, err = fs.GetStats(container.Cgroups)
 	}
-	containerStats.CgroupStats = stats
-	networkStats, err := network.GetStats(&state.NetworkState)
+
 	if err != nil {
-		return &containerStats, err
+		return stats, err
 	}
-	containerStats.NetworkStats = networkStats
 
-	return &containerStats, nil
+	stats.NetworkStats, err = network.GetStats(&state.NetworkState)
+
+	return stats, err
 }

cgroups/systemd/apply_systemd.go

@@ -32,7 +32,7 @@ var (
 	connLock              sync.Mutex
 	theConn               *systemd1.Conn
 	hasStartTransientUnit bool
-	subsystems = map[string]subsystem{
+	subsystems            = map[string]subsystem{
 		"devices":    &fs.DevicesGroup{},
 		"memory":     &fs.MemoryGroup{},
 		"cpu":        &fs.CpuGroup{},
@@ -417,15 +417,14 @@ func getUnitName(c *cgroups.Cgroup) string {
  * http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/#readingaccountinginformation.
  */
 func GetStats(c *cgroups.Cgroup) (*cgroups.Stats, error) {
-	var subsystemPath string
-	var err error
-
 	stats := cgroups.NewStats()
 
 	for sysname, sys := range subsystems {
-		if subsystemPath, err = getSubsystemPath(c, sysname); err != nil {
+		subsystemPath, err := getSubsystemPath(c, sysname)
+		if err != nil {
 			return nil, err
 		}
+
 		if err := sys.GetStats(subsystemPath, stats); err != nil {
 			return nil, err
 		}