Merge pull request #247 from ijc/volumes-support

Add image volume support.

pkg/opts/container.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package opts
+
+import (
+	"context"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/containers"
+	"github.com/docker/docker/pkg/system"
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+)
+
+// WithVolumes copies ownership of volume in rootfs to its corresponding host path.
+// It doesn't update runtime spec.
+// The passed in map is a host path to container path map for all volumes.
+// TODO(random-liu): Figure out whether we need to copy volume content.
+func WithVolumes(volumeMounts map[string]string) containerd.NewContainerOpts {
+	return func(ctx context.Context, client *containerd.Client, c *containers.Container) error {
+		if c.Snapshotter == "" {
+			return errors.Errorf("no snapshotter set for container")
+		}
+		if c.SnapshotKey == "" {
+			return errors.Errorf("rootfs not created for container")
+		}
+		snapshotter := client.SnapshotService(c.Snapshotter)
+		mounts, err := snapshotter.Mounts(ctx, c.SnapshotKey)
+		if err != nil {
+			return err
+		}
+		root, err := ioutil.TempDir("", "ctd-volume")
+		if err != nil {
+			return err
+		}
+		defer os.RemoveAll(root) // nolint: errcheck
+		for _, m := range mounts {
+			if err := m.Mount(root); err != nil {
+				return err
+			}
+		}
+		defer unix.Unmount(root, 0) // nolint: errcheck
+
+		for host, volume := range volumeMounts {
+			if err := copyOwnership(filepath.Join(root, volume), host); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+}
+
+// copyOwnership copies the permissions and uid:gid of the src file
+// to the dst file
+func copyOwnership(src, dst string) error {
+	stat, err := system.Stat(src)
+	if err != nil {
+		return err
+	}
+
+	dstStat, err := system.Stat(dst)
+	if err != nil {
+		return err
+	}
+
+	// In some cases, even though UID/GID match and it would effectively be a no-op,
+	// this can return a permission denied error... for example if this is an NFS
+	// mount.
+	// Since it's not really an error that we can't chown to the same UID/GID, don't
+	// even bother trying in such cases.
+	if stat.UID() != dstStat.UID() || stat.GID() != dstStat.GID() {
+		if err := os.Chown(dst, int(stat.UID()), int(stat.GID())); err != nil {
+			return err
+		}
+	}
+
+	if stat.Mode() != dstStat.Mode() {
+		return os.Chmod(dst, os.FileMode(stat.Mode()))
+	}
+	return nil
+}

pkg/os/os.go

@@ -20,6 +20,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 
 	"github.com/containerd/fifo"
 	"github.com/docker/docker/pkg/mount"
@@ -34,6 +35,7 @@ type OS interface {
 	RemoveAll(path string) error
 	OpenFifo(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error)
 	Stat(name string) (os.FileInfo, error)
+	ResolveSymbolicLink(name string) (string, error)
 	CopyFile(src, dest string, perm os.FileMode) error
 	WriteFile(filename string, data []byte, perm os.FileMode) error
 	Mount(source string, target string, fstype string, flags uintptr, data string) error
@@ -63,6 +65,18 @@ func (RealOS) Stat(name string) (os.FileInfo, error) {
 	return os.Stat(name)
 }
 
+// ResolveSymbolicLink will follow any symbolic links
+func (RealOS) ResolveSymbolicLink(path string) (string, error) {
+	info, err := os.Lstat(path)
+	if err != nil {
+		return "", err
+	}
+	if info.Mode()&os.ModeSymlink != os.ModeSymlink {
+		return path, nil
+	}
+	return filepath.EvalSymlinks(path)
+}
+
 // CopyFile copys src file to dest file
 func (RealOS) CopyFile(src, dest string, perm os.FileMode) error {
 	in, err := os.Open(src)

pkg/os/testing/fake_os.go

@@ -39,16 +39,17 @@ type CalledDetail struct {
 // of the real call.
 type FakeOS struct {
 	sync.Mutex
-	MkdirAllFn  func(string, os.FileMode) error
-	RemoveAllFn func(string) error
-	OpenFifoFn  func(context.Context, string, int, os.FileMode) (io.ReadWriteCloser, error)
-	StatFn      func(string) (os.FileInfo, error)
-	CopyFileFn  func(string, string, os.FileMode) error
-	WriteFileFn func(string, []byte, os.FileMode) error
-	MountFn     func(source string, target string, fstype string, flags uintptr, data string) error
-	UnmountFn   func(target string, flags int) error
-	calls       []CalledDetail
-	errors      map[string]error
+	MkdirAllFn            func(string, os.FileMode) error
+	RemoveAllFn           func(string) error
+	OpenFifoFn            func(context.Context, string, int, os.FileMode) (io.ReadWriteCloser, error)
+	StatFn                func(string) (os.FileInfo, error)
+	ResolveSymbolicLinkFn func(string) (string, error)
+	CopyFileFn            func(string, string, os.FileMode) error
+	WriteFileFn           func(string, []byte, os.FileMode) error
+	MountFn               func(source string, target string, fstype string, flags uintptr, data string) error
+	UnmountFn             func(target string, flags int) error
+	calls                 []CalledDetail
+	errors                map[string]error
 }
 
 var _ osInterface.OS = &FakeOS{}
@@ -160,6 +161,19 @@ func (f *FakeOS) Stat(name string) (os.FileInfo, error) {
 	return nil, nil
 }
 
+// ResolveSymbolicLink is a fake call that invokes ResolveSymbolicLinkFn or returns its input
+func (f *FakeOS) ResolveSymbolicLink(path string) (string, error) {
+	f.appendCalls("ResolveSymbolicLink", path)
+	if err := f.getError("ResolveSymbolicLink"); err != nil {
+		return "", err
+	}
+
+	if f.ResolveSymbolicLinkFn != nil {
+		return f.ResolveSymbolicLinkFn(path)
+	}
+	return path, nil
+}
+
 // CopyFile is a fake call that invokes CopyFileFn or just return nil.
 func (f *FakeOS) CopyFile(src, dest string, perm os.FileMode) error {
 	f.appendCalls("CopyFile", src, dest, perm)