agent: Add support for local storage

Local storage is just a directory created inside the VM.
This will use whatever the storage driver is for the container
rootfs. This will normally be 9p, but in some cases could be
device mapper. In this case the directory will benefit from the improved
performance of device mapper.

Fixes kata-containers#524

Signed-off-by: Alex Price <aprice@atlassian.com>

device.go

@@ -31,6 +31,7 @@ const (
 	driverSCSIType      = "scsi"
 	driverNvdimmType    = "nvdimm"
 	driverEphemeralType = "ephemeral"
+	driverLocalType     = "local"
 )
 
 const (

mount.go

@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"syscall"
 
@@ -176,6 +177,19 @@ func parseMountFlagsAndOptions(optionList []string) (int, string, error) {
 	return flags, strings.Join(options, ","), nil
 }
 
+func parseOptions(optionList []string) map[string]string {
+	options := make(map[string]string)
+	for _, opt := range optionList {
+		idx := strings.Index(opt, "=")
+		if idx < 1 {
+			continue
+		}
+		key, val := opt[:idx], opt[idx+1:]
+		options[key] = val
+	}
+	return options
+}
+
 func removeMounts(mounts []string) error {
 	for _, mount := range mounts {
 		if err := syscall.Unmount(mount, 0); err != nil {
@@ -198,6 +212,7 @@ var storageHandlerList = map[string]storageHandler{
 	driverMmioBlkType:   virtioMmioBlkStorageHandler,
 	driverSCSIType:      virtioSCSIStorageHandler,
 	driverEphemeralType: ephemeralStorageHandler,
+	driverLocalType:     localStorageHandler,
 }
 
 func ephemeralStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
@@ -215,6 +230,29 @@ func ephemeralStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
 	return "", nil
 }
 
+func localStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
+	s.Lock()
+	defer s.Unlock()
+	newStorage := s.setSandboxStorage(storage.MountPoint)
+	if newStorage {
+
+		// Extract and parse the mode out of the storage options.
+		// Default to os.ModePerm.
+		opts := parseOptions(storage.Options)
+		mode := os.ModePerm
+		if val, ok := opts["mode"]; ok {
+			m, err := strconv.ParseUint(val, 8, 32)
+			if err != nil {
+				return "", err
+			}
+			mode = os.FileMode(m)
+		}
+
+		return "", os.MkdirAll(storage.MountPoint, mode)
+	}
+	return "", nil
+}
+
 // virtio9pStorageHandler handles the storage for 9p driver.
 func virtio9pStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
 	return commonStorageHandler(storage)

mount_test.go

@@ -48,6 +48,66 @@ func TestEphemeralStorageHandlerSuccessful(t *testing.T) {
 	assert.Nil(t, err, "ephemeralStorageHandler() failed: %v", err)
 }
 
+func TestLocalStorageHandlerSuccessful(t *testing.T) {
+	skipUnlessRoot(t)
+
+	storage, err := createSafeAndFakeStorage()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer syscall.Unmount(storage.MountPoint, 0)
+	defer os.RemoveAll(storage.MountPoint)
+
+	sbs := make(map[string]*sandboxStorage)
+	_, err = localStorageHandler(storage, &sandbox{storages: sbs})
+	assert.Nil(t, err, "localStorageHandler() failed: %v", err)
+}
+
+func TestLocalStorageHandlerPermModeSuccessful(t *testing.T) {
+	skipUnlessRoot(t)
+
+	storage, err := createSafeAndFakeStorage()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer syscall.Unmount(storage.MountPoint, 0)
+	defer os.RemoveAll(storage.MountPoint)
+
+	// Set the mode to be 0400 (ready only)
+	storage.Options = []string{
+		"mode=0400",
+	}
+
+	sbs := make(map[string]*sandboxStorage)
+	_, err = localStorageHandler(storage, &sandbox{storages: sbs})
+	assert.Nil(t, err, "localStorageHandler() failed: %v", err)
+
+	// Check the mode of the mountpoint
+	info, err := os.Stat(storage.MountPoint)
+	assert.Nil(t, err)
+	assert.Equal(t, 0400|os.ModeDir, info.Mode())
+}
+
+func TestLocalStorageHandlerPermModeFailure(t *testing.T) {
+	skipUnlessRoot(t)
+
+	storage, err := createSafeAndFakeStorage()
+	if err != nil {
+		t.Fatal(err)
+	}
+	//defer syscall.Unmount(storage.MountPoint, 0)
+	//defer os.RemoveAll(storage.MountPoint)
+
+	// Set the mode to something invalid
+	storage.Options = []string{
+		"mode=abcde",
+	}
+
+	sbs := make(map[string]*sandboxStorage)
+	_, err = localStorageHandler(storage, &sandbox{storages: sbs})
+	assert.NotNil(t, err, "localStorageHandler() should have failed")
+}
+
 func TestVirtio9pStorageHandlerSuccessful(t *testing.T) {
 	skipUnlessRoot(t)