1 files changed, 155 insertions, 0 deletions
diff --git a/pkg/shim/utils/volumes.go b/pkg/shim/utils/volumes.go
new file mode 100644
index 000000000..52a428179
--- /dev/null
+++ b/pkg/shim/utils/volumes.go
@@ -0,0 +1,155 @@
+// Copyright 2018 The gVisor 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
+//
+//     https://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 utils
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"strings"
+
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+const volumeKeyPrefix = "dev.gvisor.spec.mount."
+
+var kubeletPodsDir = "/var/lib/kubelet/pods"
+
+// volumeName gets volume name from volume annotation key, example:
+//	dev.gvisor.spec.mount.NAME.share
+func volumeName(k string) string {
+	return strings.SplitN(strings.TrimPrefix(k, volumeKeyPrefix), ".", 2)[0]
+}
+
+// volumeFieldName gets volume field name from volume annotation key, example:
+//	`type` is the field of dev.gvisor.spec.mount.NAME.type
+func volumeFieldName(k string) string {
+	parts := strings.Split(strings.TrimPrefix(k, volumeKeyPrefix), ".")
+	return parts[len(parts)-1]
+}
+
+// podUID gets pod UID from the pod log path.
+func podUID(s *specs.Spec) (string, error) {
+	sandboxLogDir := s.Annotations[sandboxLogDirAnnotation]
+	if sandboxLogDir == "" {
+		return "", fmt.Errorf("no sandbox log path annotation")
+	}
+	fields := strings.Split(filepath.Base(sandboxLogDir), "_")
+	switch len(fields) {
+	case 1: // This is the old CRI logging path.
+		return fields[0], nil
+	case 3: // This is the new CRI logging path.
+		return fields[2], nil
+	}
+	return "", fmt.Errorf("unexpected sandbox log path %q", sandboxLogDir)
+}
+
+// isVolumeKey checks whether an annotation key is for volume.
+func isVolumeKey(k string) bool {
+	return strings.HasPrefix(k, volumeKeyPrefix)
+}
+
+// volumeSourceKey constructs the annotation key for volume source.
+func volumeSourceKey(volume string) string {
+	return volumeKeyPrefix + volume + ".source"
+}
+
+// volumePath searches the volume path in the kubelet pod directory.
+func volumePath(volume, uid string) (string, error) {
+	// TODO: Support subpath when gvisor supports pod volume bind mount.
+	volumeSearchPath := fmt.Sprintf("%s/%s/volumes/*/%s", kubeletPodsDir, uid, volume)
+	dirs, err := filepath.Glob(volumeSearchPath)
+	if err != nil {
+		return "", err
+	}
+	if len(dirs) != 1 {
+		return "", fmt.Errorf("unexpected matched volume list %v", dirs)
+	}
+	return dirs[0], nil
+}
+
+// isVolumePath checks whether a string is the volume path.
+func isVolumePath(volume, path string) (bool, error) {
+	// TODO: Support subpath when gvisor supports pod volume bind mount.
+	volumeSearchPath := fmt.Sprintf("%s/*/volumes/*/%s", kubeletPodsDir, volume)
+	return filepath.Match(volumeSearchPath, path)
+}
+
+// UpdateVolumeAnnotations add necessary OCI annotations for gvisor
+// volume optimization.
+func UpdateVolumeAnnotations(bundle string, s *specs.Spec) error {
+	var (
+		uid string
+		err error
+	)
+	if IsSandbox(s) {
+		uid, err = podUID(s)
+		if err != nil {
+			// Skip if we can't get pod UID, because this doesn't work
+			// for containerd 1.1.
+			return nil
+		}
+	}
+	var updated bool
+	for k, v := range s.Annotations {
+		if !isVolumeKey(k) {
+			continue
+		}
+		if volumeFieldName(k) != "type" {
+			continue
+		}
+		volume := volumeName(k)
+		if uid != "" {
+			// This is a sandbox.
+			path, err := volumePath(volume, uid)
+			if err != nil {
+				return fmt.Errorf("get volume path for %q: %w", volume, err)
+			}
+			s.Annotations[volumeSourceKey(volume)] = path
+			updated = true
+		} else {
+			// This is a container.
+			for i := range s.Mounts {
+				// An error is returned for sandbox if source
+				// annotation is not successfully applied, so
+				// it is guaranteed that the source annotation
+				// for sandbox has already been successfully
+				// applied at this point.
+				//
+				// The volume name is unique inside a pod, so
+				// matching without podUID is fine here.
+				//
+				// TODO: Pass podUID down to shim for containers to do
+				// more accurate matching.
+				if yes, _ := isVolumePath(volume, s.Mounts[i].Source); yes {
+					// gVisor requires the container mount type to match
+					// sandbox mount type.
+					s.Mounts[i].Type = v
+					updated = true
+				}
+			}
+		}
+	}
+	if !updated {
+		return nil
+	}
+	// Update bundle.
+	b, err := json.Marshal(s)
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(filepath.Join(bundle, "config.json"), b, 0666)
+}