117 lines
3.0 KiB
Go
117 lines
3.0 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package rootfs
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import (
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"context"
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"errors"
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"fmt"
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"os"
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"github.com/containerd/containerd/v2/core/mount"
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"github.com/containerd/containerd/v2/core/snapshots"
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"github.com/containerd/log"
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digest "github.com/opencontainers/go-digest"
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)
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var (
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initializers = map[string]initializerFunc{}
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)
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type initializerFunc func(string) error
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// Mounter handles mount and unmount
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type Mounter interface {
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Mount(target string, mounts ...mount.Mount) error
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Unmount(target string) error
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}
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// InitRootFS initializes the snapshot for use as a rootfs
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func InitRootFS(ctx context.Context, name string, parent digest.Digest, readonly bool, snapshotter snapshots.Snapshotter, mounter Mounter) ([]mount.Mount, error) {
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_, err := snapshotter.Stat(ctx, name)
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if err == nil {
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return nil, errors.New("rootfs already exists")
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}
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// TODO: ensure not exist error once added to snapshot package
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parentS := parent.String()
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initName := defaultInitializer
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initFn := initializers[initName]
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if initFn != nil {
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parentS, err = createInitLayer(ctx, parentS, initName, initFn, snapshotter, mounter)
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if err != nil {
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return nil, err
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}
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}
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if readonly {
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return snapshotter.View(ctx, name, parentS)
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}
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return snapshotter.Prepare(ctx, name, parentS)
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}
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func createInitLayer(ctx context.Context, parent, initName string, initFn func(string) error, snapshotter snapshots.Snapshotter, mounter Mounter) (_ string, retErr error) {
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initS := fmt.Sprintf("%s %s", parent, initName)
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if _, err := snapshotter.Stat(ctx, initS); err == nil {
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return initS, nil
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}
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// TODO: ensure not exist error once added to snapshot package
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// Create tempdir
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td, err := os.MkdirTemp(os.Getenv("XDG_RUNTIME_DIR"), "create-init-")
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if err != nil {
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return "", err
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}
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defer os.RemoveAll(td)
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mounts, err := snapshotter.Prepare(ctx, td, parent)
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if err != nil {
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return "", err
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}
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defer func() {
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if retErr != nil {
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if rerr := snapshotter.Remove(ctx, td); rerr != nil {
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log.G(ctx).Errorf("Failed to remove snapshot %s: %v", td, rerr)
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}
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}
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}()
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if err = mounter.Mount(td, mounts...); err != nil {
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return "", err
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}
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if err = initFn(td); err != nil {
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if merr := mounter.Unmount(td); merr != nil {
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log.G(ctx).Errorf("Failed to unmount %s: %v", td, merr)
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}
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return "", err
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}
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if err = mounter.Unmount(td); err != nil {
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return "", err
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}
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if err := snapshotter.Commit(ctx, initS, td); err != nil {
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return "", err
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}
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return initS, nil
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}
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