[release/1.6] Fix snapshotter root path when not under containerd root

pkg/cri/cri.go

@@ -55,6 +55,7 @@ func init() {
 			plugin.EventPlugin,
 			plugin.ServicePlugin,
 			plugin.WarningPlugin,
+			plugin.SnapshotPlugin,
 		},
 		InitFn: initCRIService,
 	})

pkg/cri/server/service.go

@@ -17,7 +17,9 @@
 package server
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -127,6 +129,11 @@ type criService struct {
 func NewCRIService(config criconfig.Config, client *containerd.Client, warn warning.Service) (CRIService, error) {
 	var err error
 	labels := label.NewStore()
+
+	if client.SnapshotService(config.ContainerdConfig.Snapshotter) == nil {
+		return nil, fmt.Errorf("failed to find snapshotter %q", config.ContainerdConfig.Snapshotter)
+	}
+
 	c := &criService{
 		config:                      config,
 		client:                      client,
@@ -147,7 +154,11 @@ func NewCRIService(config criconfig.Config, client *containerd.Client, warn warn
 		return nil, fmt.Errorf("failed to find snapshotter %q", c.config.ContainerdConfig.Snapshotter)
 	}
 
-	c.imageFSPath = imageFSPath(config.ContainerdRootDir, config.ContainerdConfig.Snapshotter)
+	c.imageFSPath = imageFSPath(
+		config.ContainerdRootDir,
+		config.ContainerdConfig.Snapshotter,
+		client,
+	)
 	logrus.Infof("Get image filesystem path %q", c.imageFSPath)
 
 	if err := c.initPlatform(); err != nil {
@@ -331,8 +342,40 @@ func (c *criService) register(s *grpc.Server) error {
 
 // imageFSPath returns containerd image filesystem path.
 // Note that if containerd changes directory layout, we also needs to change this.
-func imageFSPath(rootDir, snapshotter string) string {
-	return filepath.Join(rootDir, fmt.Sprintf("%s.%s", plugin.SnapshotPlugin, snapshotter))
+func imageFSPath(rootDir, snapshotter string, client *containerd.Client) string {
+	introspection := func() (string, error) {
+		filters := []string{fmt.Sprintf("type==%s, id==%s", plugin.SnapshotPlugin, snapshotter)}
+		in := client.IntrospectionService()
+
+		resp, err := in.Plugins(context.Background(), filters)
+		if err != nil {
+			return "", err
+		}
+
+		if len(resp.Plugins) <= 0 {
+			return "", fmt.Errorf("inspection service could not find snapshotter %s plugin", snapshotter)
+		}
+
+		sn := resp.Plugins[0]
+		if root, ok := sn.Exports[plugin.SnapshotterRootDir]; ok {
+			return root, nil
+		}
+		return "", errors.New("snapshotter does not export root path")
+	}
+
+	var imageFSPath string
+	path, err := introspection()
+	if err != nil {
+		logrus.WithError(err).WithField("snapshotter", snapshotter).Warn("snapshotter doesn't export root path")
+		imageFSPath = filepath.Join(
+			rootDir,
+			plugin.SnapshotPlugin.String()+"."+snapshotter,
+		)
+	} else {
+		imageFSPath = path
+	}
+
+	return imageFSPath
 }
 
 func loadOCISpec(filename string) (*oci.Spec, error) {

plugin/plugin.go

@@ -92,6 +92,10 @@ const (
 	DeprecationsPlugin = "deprecations"
 )
 
+const (
+	SnapshotterRootDir = "root"
+)
+
 // Registration contains information for registering a plugin
 type Registration struct {
 	// Type of the plugin

services/server/config/config.go

@@ -164,8 +164,10 @@ type CgroupConfig struct {
 
 // ProxyPlugin provides a proxy plugin configuration
 type ProxyPlugin struct {
-	Type    string `toml:"type"`
-	Address string `toml:"address"`
+	Type     string            `toml:"type"`
+	Address  string            `toml:"address"`
+	Platform string            `toml:"platform"`
+	Exports  map[string]string `toml:"exports"`
 }
 
 // BoltConfig defines the configuration values for the bolt plugin, which is

services/server/server.go

@@ -39,6 +39,7 @@ import (
 	metrics "github.com/docker/go-metrics"
 	grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
 	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
 	bolt "go.etcd.io/bbolt"
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"google.golang.org/grpc"
@@ -59,6 +60,7 @@ import (
 	"github.com/containerd/containerd/pkg/deprecation"
 	"github.com/containerd/containerd/pkg/dialer"
 	"github.com/containerd/containerd/pkg/timeout"
+	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/containerd/plugin"
 	srvconfig "github.com/containerd/containerd/services/server/config"
 	"github.com/containerd/containerd/services/warning"
@@ -549,6 +551,8 @@ func LoadPlugins(ctx context.Context, config *srvconfig.Config) ([]*plugin.Regis
 			f func(*grpc.ClientConn) interface{}
 
 			address = pp.Address
+			p       v1.Platform
+			err     error
 		)
 
 		switch pp.Type {
@@ -567,12 +571,27 @@ func LoadPlugins(ctx context.Context, config *srvconfig.Config) ([]*plugin.Regis
 		default:
 			log.G(ctx).WithField("type", pp.Type).Warn("unknown proxy plugin type")
 		}
+		if pp.Platform != "" {
+			p, err = platforms.Parse(pp.Platform)
+			if err != nil {
+				log.G(ctx).WithError(err).WithField("plugin", name).Warn("skipping proxy platform with bad platform")
+			}
+		} else {
+			p = platforms.DefaultSpec()
+		}
+
+		exports := pp.Exports
+		if exports == nil {
+			exports = map[string]string{}
+		}
+		exports["address"] = address
 
 		plugin.Register(&plugin.Registration{
 			Type: t,
 			ID:   name,
 			InitFn: func(ic *plugin.InitContext) (interface{}, error) {
-				ic.Meta.Exports["address"] = address
+				ic.Meta.Exports = exports
+				ic.Meta.Platforms = append(ic.Meta.Platforms, p)
 				conn, err := clients.getClient(address)
 				if err != nil {
 					return nil, err

snapshots/btrfs/plugin/plugin.go

@@ -53,7 +53,7 @@ func init() {
 				root = config.RootPath
 			}
 
-			ic.Meta.Exports = map[string]string{"root": root}
+			ic.Meta.Exports[plugin.SnapshotterRootDir] = root
 			return btrfs.NewSnapshotter(root)
 		},
 	})

snapshots/devmapper/plugin/plugin.go

@@ -48,6 +48,7 @@ func init() {
 				config.RootPath = ic.Root
 			}
 
+			ic.Meta.Exports[plugin.SnapshotterRootDir] = config.RootPath
 			return devmapper.NewSnapshotter(ic.Context, config)
 		},
 	})

snapshots/native/plugin/plugin.go

@@ -48,6 +48,7 @@ func init() {
 				root = config.RootPath
 			}
 
+			ic.Meta.Exports[plugin.SnapshotterRootDir] = root
 			return native.NewSnapshotter(root)
 		},
 	})

snapshots/overlay/plugin/plugin.go

@@ -68,7 +68,7 @@ func init() {
 				oOpts = append(oOpts, overlay.WithMountOptions(config.MountOptions))
 			}
 
-			ic.Meta.Exports["root"] = root
+			ic.Meta.Exports[plugin.SnapshotterRootDir] = root
 			return overlay.NewSnapshotter(root, oOpts...)
 		},
 	})