feature: Allow multi snapshotters

ctrd/client.go

@@ -13,6 +13,8 @@ import (
 	"github.com/containerd/containerd"
 	eventstypes "github.com/containerd/containerd/api/events"
 	"github.com/containerd/containerd/api/services/introspection/v1"
+	"github.com/containerd/containerd/plugin"
+	"github.com/containerd/containerd/snapshots"
 	"github.com/containerd/typeurl"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -305,3 +307,56 @@ func (c *Client) collectContainerdEvents() {
 		}
 	}
 }
+
+// CheckSnapshotterValid checks whether the given snapshotter is valid
+func (c *Client) CheckSnapshotterValid(snapshotter string, allowMultiSnapshotter bool) error {
+	var (
+		driverFound = false
+	)
+
+	plugins, err := c.Plugins(context.Background(), []string{fmt.Sprintf("type==%s", plugin.SnapshotPlugin)})
+	if err != nil {
+		logrus.Errorf("failed to get containerd plugins: %v", err)
+		return err
+	}
+
+	for _, p := range plugins {
+		if p.Status != PluginStatusOk {
+			continue
+		}
+
+		if p.ID == snapshotter {
+			driverFound = true
+			continue
+		}
+
+		// if allowMultiSnapshotter, ignore check snapshots exist
+		if !allowMultiSnapshotter {
+			// check if other snapshotter exists snapshots
+			exist, err := c.checkSnapshotsExist(p.ID)
+			if err != nil {
+				return fmt.Errorf("failed to check snapshotter driver %s: %v", p.ID, err)
+			}
+
+			if exist {
+				return fmt.Errorf("current snapshotter driver is %s, cannot change to %s", p.ID, snapshotter)
+			}
+		}
+	}
+
+	if !driverFound {
+		return fmt.Errorf("containerd not support snapshotter driver %s", snapshotter)
+	}
+
+	return nil
+}
+
+func (c *Client) checkSnapshotsExist(snapshotter string) (existSnapshot bool, err error) {
+	fn := func(c context.Context, s snapshots.Info) error {
+		existSnapshot = true
+		return nil
+	}
+
+	err = c.WalkSnapshot(context.Background(), snapshotter, fn)
+	return
+}

ctrd/interface.go

@@ -27,6 +27,7 @@ type APIClient interface {
 	Version(ctx context.Context) (containerd.Version, error)
 	Cleanup() error
 	Plugins(ctx context.Context, filters []string) ([]Plugin, error)
+	CheckSnapshotterValid(snapshotter string, allowMultiSnapshotter bool) error
 }
 
 // ContainerAPIClient provides access to containerd container features.

daemon/config/config.go

@@ -117,6 +117,9 @@ type Config struct {
 
 	// Snapshotter is passed to containerd, default to overlayfs
 	Snapshotter string `json:"snapshotter,omitempty"`
+
+	// AllowMultiSnapshotter allows multi snapshotter, default false
+	AllowMultiSnapshotter bool `json:"allow-multi-snapshotter,omitempty"`
 }
 
 // GetCgroupDriver gets cgroup driver used in runc.

daemon/daemon.go

@@ -105,7 +105,7 @@ func NewDaemon(cfg *config.Config) *Daemon {
 		ctrd.SetSnapshotterName(cfg.Snapshotter)
 	}
 
-	if err = checkSnapshotterValid(ctrd.CurrentSnapshotterName(), ctrdClient); err != nil {
+	if err = ctrdClient.CheckSnapshotterValid(ctrd.CurrentSnapshotterName(), cfg.AllowMultiSnapshotter); err != nil {
 		logrus.Errorf("failed to check snapshotter driver: %v", err)
 		return nil
 	}

daemon/daemon_utils.go

@@ -1,19 +1,13 @@
 package daemon
 
 import (
-	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/alibaba/pouch/apis/types"
-	"github.com/alibaba/pouch/ctrd"
-
-	"github.com/containerd/containerd/plugin"
-	"github.com/containerd/containerd/snapshots"
-	"github.com/sirupsen/logrus"
 )
 
 var (
@@ -58,53 +52,3 @@ func initialRuntime(baseDir string, runtimes map[string]types.Runtime) error {
 
 	return nil
 }
-
-// checkSnapshotterValid checks whether the given snapshotter is valid
-func checkSnapshotterValid(snapshotter string, ctrdClient ctrd.APIClient) error {
-	var (
-		driverFound = false
-	)
-
-	plugins, err := ctrdClient.Plugins(context.Background(), []string{fmt.Sprintf("type==%s", plugin.SnapshotPlugin)})
-	if err != nil {
-		logrus.Errorf("failed to get containerd plugins: %v", err)
-		return err
-	}
-
-	for _, p := range plugins {
-		if p.Status != ctrd.PluginStatusOk {
-			continue
-		}
-
-		if p.ID == snapshotter {
-			driverFound = true
-			continue
-		}
-
-		// check if other snapshotter exists snapshots
-		exist, err := checkSnapshotsExist(p.ID, ctrdClient)
-		if exist {
-			return fmt.Errorf("current snapshotter driver is %s, cannot change to %s", p.ID, snapshotter)
-		}
-
-		if err != nil {
-			return fmt.Errorf("failed to check snapshotter driver %s: %v", p.ID, err)
-		}
-	}
-
-	if !driverFound {
-		return fmt.Errorf("containerd not support snapshotter driver %s", snapshotter)
-	}
-
-	return nil
-}
-
-func checkSnapshotsExist(snapshotter string, ctrdClient ctrd.APIClient) (existSnapshot bool, err error) {
-	fn := func(c context.Context, s snapshots.Info) error {
-		existSnapshot = true
-		return nil
-	}
-
-	err = ctrdClient.WalkSnapshot(context.Background(), snapshotter, fn)
-	return
-}

main.go

@@ -99,6 +99,7 @@ func setupFlags(cmd *cobra.Command) {
 	flagSet.StringVar(&cfg.QuotaDriver, "quota-driver", "", "Set quota driver(grpquota/prjquota), if not set, it will set by kernel version")
 	flagSet.StringVar(&cfg.ConfigFile, "config-file", "/etc/pouch/config.json", "Configuration file of pouchd")
 	flagSet.StringVar(&cfg.Snapshotter, "snapshotter", "overlayfs", "Snapshotter driver of pouchd, it will be passed to containerd")
+	flagSet.BoolVar(&cfg.AllowMultiSnapshotter, "allow-multi-snapshotter", false, "If set true, pouchd will allow multi snapshotter")
 
 	// volume config
 	flagSet.StringVar(&cfg.VolumeConfig.DriverAlias, "volume-driver-alias", "", "Set volume driver alias, <name=alias>[;name1=alias1]")

test/cli_snapshotter_test.go

@@ -96,6 +96,39 @@ func (suite *PouchSnapshotterSuite) TestOldSnapshotterNotClean(c *check.C) {
 	dcfg.KillDaemon()
 }
 
+// TestAllowMultiSnapshotter tests pouchd with two snapshotter
+func (suite *PouchSnapshotterSuite) TestAllowMultiSnapshotter(c *check.C) {
+	dcfg, err := StartDefaultDaemon("--snapshotter", "overlayfs", "--allow-multi-snapshotter")
+	c.Assert(err, check.IsNil)
+
+	fileSystemInfo, err := mount.Lookup(dcfg.HomeDir)
+	c.Assert(err, check.IsNil)
+
+	if fileSystemInfo.FSType != "btrfs" {
+		dcfg.KillDaemon()
+		c.Skip("btrfs is not supported! Ignore test suite TestOldSnapshotterNotClean.")
+	}
+
+	result := RunWithSpecifiedDaemon(dcfg, "pull", busyboxImage)
+	c.Assert(result.ExitCode, check.Equals, 0)
+	dcfg.KillDaemon()
+	time.Sleep(10 * time.Second)
+
+	dcfg, err = StartDefaultDaemon("--snapshotter", "btrfs", "--allow-multi-snapshotter")
+	c.Assert(err, check.IsNil)
+
+	dcfg.KillDaemon()
+	time.Sleep(10 * time.Second)
+
+	// clean image
+	dcfg, err = StartDefaultDaemon("--snapshotter", "overlayfs")
+	c.Assert(err, check.IsNil)
+
+	result = RunWithSpecifiedDaemon(dcfg, "rmi", busyboxImage)
+	c.Assert(result.ExitCode, check.Equals, 0)
+	dcfg.KillDaemon()
+}
+
 // checkSnapshotsDir returns snapshots directory names by given snapshotter name
 func checkSnapshotsDir(homeDir string, snapshotter string) ([]string, error) {
 	const snapshotterPrefix = "io.containerd.snapshotter.v1."