Implement mounting via stage directory

Previously, multiple containers with the same mounted volume resulted in multiple
FUSE processes. This behaviour was breaking parallel modifications from different
containers, consumed extra resources, and after mounting via systemd was introduced,
led to the total inability to mount the same volume into multiple containers on
the same host.

Now only one FUSE process is started per volume, per host.

deploy/kubernetes/csi-s3.yaml

@@ -103,6 +103,9 @@ spec:
           volumeMounts:
             - name: plugin-dir
               mountPath: /csi
+            - name: stage-dir
+              mountPath: /var/lib/kubelet/plugins/kubernetes.io/csi/ru.yandex.s3.csi
+              mountPropagation: "Bidirectional"
             - name: pods-mount-dir
               mountPath: /var/lib/kubelet/pods
               mountPropagation: "Bidirectional"
@@ -119,6 +122,10 @@ spec:
           hostPath:
             path: /var/lib/kubelet/plugins/ru.yandex.s3.csi
             type: DirectoryOrCreate
+        - name: stage-dir
+          hostPath:
+            path: /var/lib/kubelet/plugins/kubernetes.io/csi/ru.yandex.s3.csi
+            type: DirectoryOrCreate
         - name: pods-mount-dir
           hostPath:
             path: /var/lib/kubelet/pods

pkg/driver/driver.go

@@ -33,7 +33,7 @@ type driver struct {
 }
 
 var (
-	vendorVersion = "v1.2.0"
+	vendorVersion = "v1.34.6"
 	driverName    = "ru.yandex.s3.csi"
 )
 

pkg/driver/nodeserver.go

@@ -19,6 +19,7 @@ package driver
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"regexp"
 	"strconv"
 
@@ -68,7 +69,6 @@ func (ns *nodeServer) NodePublishVolume(ctx context.Context, req *csi.NodePublis
 	volumeID := req.GetVolumeId()
 	targetPath := req.GetTargetPath()
 	stagingTargetPath := req.GetStagingTargetPath()
-	bucketName, prefix := volumeIDToBucketPrefix(volumeID)
 
 	// Check arguments
 	if req.GetVolumeCapability() == nil {
@@ -100,18 +100,12 @@ func (ns *nodeServer) NodePublishVolume(ctx context.Context, req *csi.NodePublis
 	glog.V(4).Infof("target %v\nreadonly %v\nvolumeId %v\nattributes %v\nmountflags %v\n",
 		targetPath, readOnly, volumeID, attrib, mountFlags)
 
-	s3, err := s3.NewClientFromSecret(req.GetSecrets())
+	cmd := exec.Command("mount", "--bind", stagingTargetPath, targetPath)
+	cmd.Stderr = os.Stderr
+	glog.V(3).Infof("Binding volume %v from %v to %v", volumeID, stagingTargetPath, targetPath)
+	out, err := cmd.Output()
 	if err != nil {
-		return nil, fmt.Errorf("failed to initialize S3 client: %s", err)
-	}
-
-	meta := getMeta(bucketName, prefix, req.VolumeContext)
-	mounter, err := mounter.New(meta, s3.Config)
-	if err != nil {
-		return nil, err
-	}
-	if err := mounter.Mount(stagingTargetPath, targetPath, volumeID); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("Error running mount --bind %v %v: %s", stagingTargetPath, targetPath, out)
 	}
 
 	glog.V(4).Infof("s3: volume %s successfully mounted to %s", volumeID, targetPath)
@@ -131,7 +125,7 @@ func (ns *nodeServer) NodeUnpublishVolume(ctx context.Context, req *csi.NodeUnpu
 		return nil, status.Error(codes.InvalidArgument, "Target path missing in request")
 	}
 
-	if err := mounter.FuseUnmount(targetPath); err != nil {
+	if err := mounter.Unmount(targetPath); err != nil {
 		return nil, status.Error(codes.Internal, err.Error())
 	}
 	glog.V(4).Infof("s3: volume %s has been unmounted.", volumeID)
@@ -174,7 +168,7 @@ func (ns *nodeServer) NodeStageVolume(ctx context.Context, req *csi.NodeStageVol
 	if err != nil {
 		return nil, err
 	}
-	if err := mounter.Stage(stagingTargetPath); err != nil {
+	if err := mounter.Mount(stagingTargetPath, volumeID); err != nil {
 		return nil, err
 	}
 
@@ -193,6 +187,22 @@ func (ns *nodeServer) NodeUnstageVolume(ctx context.Context, req *csi.NodeUnstag
 		return nil, status.Error(codes.InvalidArgument, "Target path missing in request")
 	}
 
+	proc, err := mounter.FindFuseMountProcess(stagingTargetPath)
+	if err != nil {
+		return nil, err
+	}
+	exists := false
+	if proc == nil {
+		exists, err = mounter.SystemdUnmount(volumeID)
+		if exists && err != nil {
+			return nil, err
+		}
+	}
+	if !exists {
+		err = mounter.FuseUnmount(stagingTargetPath)
+	}
+	glog.V(4).Infof("s3: volume %s has been unmounted from stage path %v.", volumeID, stagingTargetPath)
+
 	return &csi.NodeUnstageVolumeResponse{}, nil
 }
 

pkg/mounter/geesefs.go

@@ -3,11 +3,11 @@ package mounter
 import (
 	"fmt"
 	"os"
-	"strings"
 	"time"
 
 	systemd "github.com/coreos/go-systemd/v22/dbus"
 	dbus "github.com/godbus/dbus/v5"
+	"github.com/golang/glog"
 
 	"github.com/yandex-cloud/k8s-csi-s3/pkg/s3"
 )
@@ -35,14 +35,6 @@ func newGeeseFSMounter(meta *s3.FSMeta, cfg *s3.Config) (Mounter, error) {
 	}, nil
 }
 
-func (geesefs *geesefsMounter) Stage(stageTarget string) error {
-	return nil
-}
-
-func (geesefs *geesefsMounter) Unstage(stageTarget string) error {
-	return nil
-}
-
 func (geesefs *geesefsMounter) CopyBinary(from, to string) error {
 	st, err := os.Stat(from)
 	if err != nil {
@@ -87,7 +79,7 @@ func (geesefs *geesefsMounter) MountDirect(target string, args []string) error {
 	return fuseMount(target, geesefsCmd, args)
 }
 
-func (geesefs *geesefsMounter) Mount(source, target, volumeID string) error {
+func (geesefs *geesefsMounter) Mount(target, volumeID string) error {
 	fullPath := fmt.Sprintf("%s:%s", geesefs.meta.BucketName, geesefs.meta.Prefix)
 	var args []string
 	if geesefs.region != "" {
@@ -113,7 +105,7 @@ func (geesefs *geesefsMounter) Mount(source, target, volumeID string) error {
 	}
 	conn, err := systemd.New()
 	if err != nil {
-		fmt.Printf("Failed to connect to systemd dbus service: %v, starting geesefs directly\n", err)
+		glog.Errorf("Failed to connect to systemd dbus service: %v, starting geesefs directly", err)
 		return geesefs.MountDirect(target, args)
 	}
 	defer conn.Close()
@@ -127,7 +119,7 @@ func (geesefs *geesefsMounter) Mount(source, target, volumeID string) error {
 	}
 	args = append([]string{pluginDir+"/geesefs", "-f", "-o", "allow_other", "--endpoint", geesefs.endpoint}, args...)
 	unitName := "geesefs-"+systemd.PathBusEscape(volumeID)+".service"
-	props := []systemd.Property{
+	newProps := []systemd.Property{
 		systemd.Property{
 			Name: "Description",
 			Value: dbus.MakeVariant("GeeseFS mount for Kubernetes volume "+volumeID),
@@ -142,13 +134,35 @@ func (geesefs *geesefsMounter) Mount(source, target, volumeID string) error {
 			Value: dbus.MakeVariant("inactive-or-failed"),
 		},
 	}
-	_, err = conn.StartTransientUnit(unitName, "replace", props, nil)
-	if err != nil && strings.Contains(err.Error(), "already exists") {
+	unitProps, err := conn.GetAllProperties(unitName)
+	if err == nil {
+		// Unit already exists
+		if s, ok := unitProps["ActiveState"].(string); ok && (s == "active" || s == "activating" || s == "reloading") {
+			// Unit is already active
+			curPath := ""
+			prevExec, ok := unitProps["ExecStart"].([][]interface{})
+			if ok && len(prevExec) > 0 && len(prevExec[0]) >= 2 {
+				execArgs, ok := prevExec[0][1].([]string)
+				if ok && len(execArgs) >= 2 {
+					curPath = execArgs[len(execArgs)-1]
+				}
+			}
+			if curPath != target {
+				return fmt.Errorf(
+					"GeeseFS for volume %v is already mounted on host, but"+
+					" in a different directory. We want %v, but it's in %v",
+					volumeID, target, curPath,
+				)
+			}
+			// Already mounted at right location
+			return nil
+		} else {
 			// Stop and garbage collect the unit if automatic collection didn't work for some reason
 			conn.StopUnit(unitName, "replace", nil)
 			conn.ResetFailedUnit(unitName)
-		_, err = conn.StartTransientUnit(unitName, "replace", props, nil)
 		}
+	}
+	_, err = conn.StartTransientUnit(unitName, "replace", newProps, nil)
 	if err != nil {
 		return fmt.Errorf("Error starting systemd unit %s on host: %v", unitName, err)
 	}

pkg/mounter/mounter.go

@@ -11,18 +11,18 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/yandex-cloud/k8s-csi-s3/pkg/s3"
+	systemd "github.com/coreos/go-systemd/v22/dbus"
 	"github.com/golang/glog"
 	"github.com/mitchellh/go-ps"
 	"k8s.io/kubernetes/pkg/util/mount"
+
+	"github.com/yandex-cloud/k8s-csi-s3/pkg/s3"
 )
 
 // Mounter interface which can be implemented
 // by the different mounter types
 type Mounter interface {
-	Stage(stagePath string) error
-	Unstage(stagePath string) error
-	Mount(source, target, volumeID string) error
+	Mount(target, volumeID string) error
 }
 
 const (
@@ -70,12 +70,40 @@ func fuseMount(path string, command string, args []string) error {
 	return waitForMount(path, 10*time.Second)
 }
 
+func Unmount(path string) error {
+	if err := mount.New("").Unmount(path); err != nil {
+		return err
+	}
+	return nil
+}
+
+func SystemdUnmount(volumeID string) (bool, error) {
+	conn, err := systemd.New()
+	if err != nil {
+		glog.Errorf("Failed to connect to systemd dbus service: %v", err)
+		return false, err
+	}
+	defer conn.Close()
+	unitName := "geesefs-"+systemd.PathBusEscape(volumeID)+".service"
+	units, err := conn.ListUnitsByNames([]string{ unitName })
+	glog.Errorf("Got %v", units)
+	if err != nil {
+		glog.Errorf("Failed to list systemd unit by name %v: %v", unitName, err)
+		return false, err
+	}
+	if len(units) == 0 || units[0].ActiveState == "inactive" || units[0].ActiveState == "failed" {
+		return true, nil
+	}
+	_, err = conn.StopUnit(unitName, "replace", nil)
+	return true, err
+}
+
 func FuseUnmount(path string) error {
 	if err := mount.New("").Unmount(path); err != nil {
 		return err
 	}
 	// as fuse quits immediately, we will try to wait until the process is done
-	process, err := findFuseMountProcess(path)
+	process, err := FindFuseMountProcess(path)
 	if err != nil {
 		glog.Errorf("Error getting PID of fuse mount: %s", err)
 		return nil
@@ -107,7 +135,7 @@ func waitForMount(path string, timeout time.Duration) error {
 	}
 }
 
-func findFuseMountProcess(path string) (*os.Process, error) {
+func FindFuseMountProcess(path string) (*os.Process, error) {
 	processes, err := ps.Processes()
 	if err != nil {
 		return nil, err

pkg/mounter/rclone.go

@@ -31,15 +31,7 @@ func newRcloneMounter(meta *s3.FSMeta, cfg *s3.Config) (Mounter, error) {
 	}, nil
 }
 
-func (rclone *rcloneMounter) Stage(stageTarget string) error {
-	return nil
-}
-
-func (rclone *rcloneMounter) Unstage(stageTarget string) error {
-	return nil
-}
-
-func (rclone *rcloneMounter) Mount(source, target, volumeID string) error {
+func (rclone *rcloneMounter) Mount(target, volumeID string) error {
 	args := []string{
 		"mount",
 		fmt.Sprintf(":s3:%s", path.Join(rclone.meta.BucketName, rclone.meta.Prefix)),

pkg/mounter/s3fs.go

@@ -28,15 +28,7 @@ func newS3fsMounter(meta *s3.FSMeta, cfg *s3.Config) (Mounter, error) {
 	}, nil
 }
 
-func (s3fs *s3fsMounter) Stage(stageTarget string) error {
-	return nil
-}
-
-func (s3fs *s3fsMounter) Unstage(stageTarget string) error {
-	return nil
-}
-
-func (s3fs *s3fsMounter) Mount(source, target, volumeID string) error {
+func (s3fs *s3fsMounter) Mount(target, volumeID string) error {
 	if err := writes3fsPass(s3fs.pwFileContent); err != nil {
 		return err
 	}