Move snapshots/overlay to plugins/snapshots/overlay

Signed-off-by: Derek McGowan <derek@mcg.dev>

plugins/snapshots/overlay/plugin/plugin.go

@@ -0,0 +1,99 @@
+//go:build linux
+
+/*
+   Copyright The containerd 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 overlay
+
+import (
+	"errors"
+
+	"github.com/containerd/containerd/v2/platforms"
+	"github.com/containerd/containerd/v2/plugins"
+	"github.com/containerd/containerd/v2/plugins/snapshots/overlay"
+	"github.com/containerd/containerd/v2/plugins/snapshots/overlay/overlayutils"
+	"github.com/containerd/plugin"
+	"github.com/containerd/plugin/registry"
+)
+
+const (
+	capaRemapIds     = "remap-ids"
+	capaOnlyRemapIds = "only-remap-ids"
+)
+
+// Config represents configuration for the overlay plugin.
+type Config struct {
+	// Root directory for the plugin
+	RootPath      string `toml:"root_path"`
+	UpperdirLabel bool   `toml:"upperdir_label"`
+	SyncRemove    bool   `toml:"sync_remove"`
+
+	// slowChown allows the plugin to fallback to a recursive chown if fast options (like
+	// idmap mounts) are not available. See more info about the overhead this can have in
+	// github.com/containerd/containerd/docs/user-namespaces/.
+	SlowChown bool `toml:"slow_chown"`
+
+	// MountOptions are options used for the overlay mount (not used on bind mounts)
+	MountOptions []string `toml:"mount_options"`
+}
+
+func init() {
+	registry.Register(&plugin.Registration{
+		Type:   plugins.SnapshotPlugin,
+		ID:     "overlayfs",
+		Config: &Config{},
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			ic.Meta.Platforms = append(ic.Meta.Platforms, platforms.DefaultSpec())
+
+			config, ok := ic.Config.(*Config)
+			if !ok {
+				return nil, errors.New("invalid overlay configuration")
+			}
+
+			root := ic.Properties[plugins.PropertyRootDir]
+			if config.RootPath != "" {
+				root = config.RootPath
+			}
+
+			var oOpts []overlay.Opt
+			if config.UpperdirLabel {
+				oOpts = append(oOpts, overlay.WithUpperdirLabel)
+			}
+			if !config.SyncRemove {
+				oOpts = append(oOpts, overlay.AsynchronousRemove)
+			}
+
+			if len(config.MountOptions) > 0 {
+				oOpts = append(oOpts, overlay.WithMountOptions(config.MountOptions))
+			}
+			if ok, err := overlayutils.SupportsIDMappedMounts(); err == nil && ok {
+				oOpts = append(oOpts, overlay.WithRemapIds)
+				ic.Meta.Capabilities = append(ic.Meta.Capabilities, capaRemapIds)
+			}
+
+			if config.SlowChown {
+				oOpts = append(oOpts, overlay.WithSlowChown)
+			} else {
+				// If slowChown is false, we use capaOnlyRemapIds to signal we only
+				// allow idmap mounts.
+				ic.Meta.Capabilities = append(ic.Meta.Capabilities, capaOnlyRemapIds)
+			}
+
+			ic.Meta.Exports["root"] = root
+			return overlay.NewSnapshotter(root, oOpts...)
+		},
+	})
+}