Get rid of panic in stats for lxc

Fix containers dir

Docker-DCO-1.1-Signed-off-by: Jessie Frazelle <jess@docker.com> (github: jfrazelle)

daemon/daemon.go

@@ -1015,7 +1015,7 @@ func NewDaemonFromDirectory(config *Config, eng *engine.Engine) (*Daemon, error)
 
 	sysInfo := sysinfo.New(false)
 	const runDir = "/var/run/docker"
-	ed, err := execdrivers.NewDriver(config.ExecDriver, runDir, sysInitPath, sysInfo)
+	ed, err := execdrivers.NewDriver(config.ExecDriver, runDir, config.Root, sysInitPath, sysInfo)
 	if err != nil {
 		return nil, err
 	}

daemon/execdriver/execdrivers/execdrivers.go

@@ -10,13 +10,13 @@ import (
 	"github.com/docker/docker/pkg/sysinfo"
 )
 
-func NewDriver(name, root, initPath string, sysInfo *sysinfo.SysInfo) (execdriver.Driver, error) {
+func NewDriver(name, root, libPath, initPath string, sysInfo *sysinfo.SysInfo) (execdriver.Driver, error) {
 	switch name {
 	case "lxc":
 		// we want to give the lxc driver the full docker root because it needs
 		// to access and write config and template files in /var/lib/docker/containers/*
 		// to be backwards compatible
-		return lxc.NewDriver(root, initPath, sysInfo.AppArmor)
+		return lxc.NewDriver(root, libPath, initPath, sysInfo.AppArmor)
 	case "native":
 		return native.NewDriver(path.Join(root, "execdriver", "native"), initPath)
 	}

daemon/execdriver/lxc/driver.go

@@ -36,6 +36,7 @@ var ErrExec = errors.New("Unsupported: Exec is not supported by the lxc driver")
 
 type driver struct {
 	root             string // root path for the driver to use
+	libPath          string
 	initPath         string
 	apparmor         bool
 	sharedRoot       bool
@@ -49,7 +50,7 @@ type activeContainer struct {
 	cmd       *exec.Cmd
 }
 
-func NewDriver(root, initPath string, apparmor bool) (*driver, error) {
+func NewDriver(root, libPath, initPath string, apparmor bool) (*driver, error) {
 	if err := os.MkdirAll(root, 0700); err != nil {
 		return nil, err
 	}
@@ -64,6 +65,7 @@ func NewDriver(root, initPath string, apparmor bool) (*driver, error) {
 	return &driver{
 		apparmor:         apparmor,
 		root:             root,
+		libPath:          libPath,
 		initPath:         initPath,
 		sharedRoot:       rootIsShared(),
 		activeContainers: make(map[string]*activeContainer),
@@ -669,7 +671,7 @@ func rootIsShared() bool {
 }
 
 func (d *driver) containerDir(containerId string) string {
-	return path.Join(d.root, "containers", containerId)
+	return path.Join(d.libPath, "containers", containerId)
 }
 
 func (d *driver) generateLXCConfig(c *execdriver.Command) (string, error) {
@@ -699,7 +701,7 @@ func (d *driver) generateEnvConfig(c *execdriver.Command) error {
 	if err != nil {
 		return err
 	}
-	p := path.Join(d.root, "containers", c.ID, "config.env")
+	p := path.Join(d.libPath, "containers", c.ID, "config.env")
 	c.Mounts = append(c.Mounts, execdriver.Mount{
 		Source:      p,
 		Destination: "/.dockerenv",
@@ -791,5 +793,8 @@ func (d *driver) Exec(c *execdriver.Command, processConfig *execdriver.ProcessCo
 }
 
 func (d *driver) Stats(id string) (*execdriver.ResourceStats, error) {
+	if _, ok := d.activeContainers[id]; !ok {
+		return nil, fmt.Errorf("%s is not a key in active containers", id)
+	}
 	return execdriver.Stats(d.containerDir(id), d.activeContainers[id].container.Cgroups.Memory, d.machineMemory)
 }

daemon/execdriver/lxc/lxc_template_unit_test.go

@@ -39,7 +39,7 @@ func TestLXCConfig(t *testing.T) {
 		cpu    = cpuMin + rand.Intn(cpuMax-cpuMin)
 	)
 
-	driver, err := NewDriver(root, "", false)
+	driver, err := NewDriver(root, root, "", false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -76,7 +76,7 @@ func TestCustomLxcConfig(t *testing.T) {
 
 	os.MkdirAll(path.Join(root, "containers", "1"), 0777)
 
-	driver, err := NewDriver(root, "", false)
+	driver, err := NewDriver(root, root, "", false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -194,7 +194,7 @@ func TestCustomLxcConfigMounts(t *testing.T) {
 	}
 	os.MkdirAll(path.Join(root, "containers", "1"), 0777)
 
-	driver, err := NewDriver(root, "", false)
+	driver, err := NewDriver(root, root, "", false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -248,7 +248,7 @@ func TestCustomLxcConfigMisc(t *testing.T) {
 	}
 	defer os.RemoveAll(root)
 	os.MkdirAll(path.Join(root, "containers", "1"), 0777)
-	driver, err := NewDriver(root, "", true)
+	driver, err := NewDriver(root, root, "", true)
 
 	if err != nil {
 		t.Fatal(err)
@@ -313,7 +313,7 @@ func TestCustomLxcConfigMiscOverride(t *testing.T) {
 	}
 	defer os.RemoveAll(root)
 	os.MkdirAll(path.Join(root, "containers", "1"), 0777)
-	driver, err := NewDriver(root, "", false)
+	driver, err := NewDriver(root, root, "", false)
 	if err != nil {
 		t.Fatal(err)
 	}