Apply more structure to pod data dirs

This is makes it possible to read back "known" pods from disk without
getting other (non-pod) kubelet dirs in the mix.  Ditto for containers
within a pod.  This is just saner overall.  Pods now nest in a pods/
dir.  Likewise containers.

pkg/kubelet/kubelet.go

@@ -170,16 +170,30 @@ func (kl *Kubelet) GetRootDir() string {
 
 // GetPodsDir returns the full path to the directory under which pod
 // directories are created.
-// TODO(thockin): For now, this is the same as the root because that is assumed
-// in other code.  Will fix.
 func (kl *Kubelet) GetPodsDir() string {
-	return kl.GetRootDir()
+	return path.Join(kl.GetRootDir(), "pods")
 }
 
 // GetPodDir returns the full path to the per-pod data directory for the
 // specified pod.  This directory may not exist if the pod does not exist.
 func (kl *Kubelet) GetPodDir(podUID string) string {
-	return path.Join(kl.GetRootDir(), podUID)
+	// Backwards compat.  The "old" stuff should be removed before 1.0
+	// release.  The thinking here is this:
+	//     !old && !new = use new
+	//     !old && new  = use new
+	//     old && !new  = use old
+	//     old && new   = use new (but warn)
+	oldPath := path.Join(kl.GetRootDir(), podUID)
+	oldExists := dirExists(oldPath)
+	newPath := path.Join(kl.GetPodsDir(), podUID)
+	newExists := dirExists(newPath)
+	if oldExists && !newExists {
+		return oldPath
+	}
+	if oldExists {
+		glog.Warningf("Data dir for pod %q exists in both old and new form, using new", podUID)
+	}
+	return newPath
 }
 
 // GetPodVolumesDir returns the full path to the per-pod data directory under
@@ -193,7 +207,31 @@ func (kl *Kubelet) GetPodVolumesDir(podUID string) string {
 // which container data is held for the specified pod.  This directory may not
 // exist if the pod or container does not exist.
 func (kl *Kubelet) GetPodContainerDir(podUID, ctrName string) string {
-	return path.Join(kl.GetPodDir(podUID), ctrName)
+	// Backwards compat.  The "old" stuff should be removed before 1.0
+	// release.  The thinking here is this:
+	//     !old && !new = use new
+	//     !old && new  = use new
+	//     old && !new  = use old
+	//     old && new   = use new (but warn)
+	oldPath := path.Join(kl.GetPodDir(podUID), ctrName)
+	oldExists := dirExists(oldPath)
+	newPath := path.Join(kl.GetPodDir(podUID), "containers", ctrName)
+	newExists := dirExists(newPath)
+	if oldExists && !newExists {
+		return oldPath
+	}
+	if oldExists {
+		glog.Warningf("Data dir for pod %q, container %q exists in both old and new form, using new", podUID, ctrName)
+	}
+	return newPath
+}
+
+func dirExists(path string) bool {
+	s, err := os.Stat(path)
+	if err != nil {
+		return false
+	}
+	return s.IsDir()
 }
 
 type ByCreated []*docker.Container

pkg/kubelet/kubelet_test.go

@@ -98,25 +98,117 @@ func TestKubeletDirs(t *testing.T) {
 	var exp, got string
 
 	got = kubelet.GetPodsDir()
-	exp = root
+	exp = path.Join(root, "pods")
 	if got != exp {
 		t.Errorf("expected %q', got %q", exp, got)
 	}
 
 	got = kubelet.GetPodDir("abc123")
-	exp = path.Join(root, "abc123")
+	exp = path.Join(root, "pods/abc123")
 	if got != exp {
 		t.Errorf("expected %q', got %q", exp, got)
 	}
 
 	got = kubelet.GetPodVolumesDir("abc123")
-	exp = path.Join(root, "abc123/volumes")
+	exp = path.Join(root, "pods/abc123/volumes")
 	if got != exp {
 		t.Errorf("expected %q', got %q", exp, got)
 	}
 
 	got = kubelet.GetPodContainerDir("abc123", "def456")
-	exp = path.Join(root, "abc123/def456")
+	exp = path.Join(root, "pods/abc123/containers/def456")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+}
+
+func TestKubeletDirsCompat(t *testing.T) {
+	kubelet, _, _ := newTestKubelet(t)
+	root := kubelet.rootDirectory
+	if err := os.MkdirAll(root, 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+
+	var exp, got string
+
+	// Old-style pod dir.
+	if err := os.MkdirAll(fmt.Sprintf("%s/oldpod", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+	// New-style pod dir.
+	if err := os.MkdirAll(fmt.Sprintf("%s/pods/newpod", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+	// Both-style pod dir.
+	if err := os.MkdirAll(fmt.Sprintf("%s/bothpod", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+	if err := os.MkdirAll(fmt.Sprintf("%s/pods/bothpod", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+
+	got = kubelet.GetPodDir("oldpod")
+	exp = path.Join(root, "oldpod")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	got = kubelet.GetPodDir("newpod")
+	exp = path.Join(root, "pods/newpod")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	got = kubelet.GetPodDir("bothpod")
+	exp = path.Join(root, "pods/bothpod")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	got = kubelet.GetPodDir("neitherpod")
+	exp = path.Join(root, "pods/neitherpod")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	root = kubelet.GetPodDir("newpod")
+
+	// Old-style container dir.
+	if err := os.MkdirAll(fmt.Sprintf("%s/oldctr", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+	// New-style container dir.
+	if err := os.MkdirAll(fmt.Sprintf("%s/containers/newctr", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+	// Both-style container dir.
+	if err := os.MkdirAll(fmt.Sprintf("%s/bothctr", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+	if err := os.MkdirAll(fmt.Sprintf("%s/containers/bothctr", root), 0750); err != nil {
+		t.Fatalf("can't mkdir(%q): %s", root, err)
+	}
+
+	got = kubelet.GetPodContainerDir("newpod", "oldctr")
+	exp = path.Join(root, "oldctr")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	got = kubelet.GetPodContainerDir("newpod", "newctr")
+	exp = path.Join(root, "containers/newctr")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	got = kubelet.GetPodContainerDir("newpod", "bothctr")
+	exp = path.Join(root, "containers/bothctr")
+	if got != exp {
+		t.Errorf("expected %q', got %q", exp, got)
+	}
+
+	got = kubelet.GetPodContainerDir("newpod", "neitherctr")
+	exp = path.Join(root, "containers/neitherctr")
 	if got != exp {
 		t.Errorf("expected %q', got %q", exp, got)
 	}