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image.go
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image.go
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/*
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 containerd
import (
"context"
"encoding/json"
"errors"
"fmt"
"strings"
"sync"
"sync/atomic"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/diff"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/labels"
"github.com/containerd/containerd/pkg/kmutex"
"github.com/containerd/containerd/platforms"
"github.com/containerd/containerd/rootfs"
"github.com/containerd/containerd/snapshots"
"github.com/opencontainers/go-digest"
"github.com/opencontainers/image-spec/identity"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
"golang.org/x/sync/semaphore"
)
// Image describes an image used by containers
type Image interface {
// Name of the image
Name() string
// Target descriptor for the image content
Target() ocispec.Descriptor
// Labels of the image
Labels() map[string]string
// Unpack unpacks the image's content into a snapshot
Unpack(context.Context, string, ...UnpackOpt) error
// RootFS returns the unpacked diffids that make up images rootfs.
RootFS(ctx context.Context) ([]digest.Digest, error)
// Size returns the total size of the image's packed resources.
Size(ctx context.Context) (int64, error)
// Usage returns a usage calculation for the image.
Usage(context.Context, ...UsageOpt) (int64, error)
// Config descriptor for the image.
Config(ctx context.Context) (ocispec.Descriptor, error)
// IsUnpacked returns whether or not an image is unpacked.
IsUnpacked(context.Context, string) (bool, error)
// ContentStore provides a content store which contains image blob data
ContentStore() content.Store
// Metadata returns the underlying image metadata
Metadata() images.Image
// Platform returns the platform match comparer. Can be nil.
Platform() platforms.MatchComparer
// Spec returns the OCI image spec for a given image.
Spec(ctx context.Context) (ocispec.Image, error)
}
type usageOptions struct {
manifestLimit *int
manifestOnly bool
snapshots bool
}
// UsageOpt is used to configure the usage calculation
type UsageOpt func(*usageOptions) error
// WithUsageManifestLimit sets the limit to the number of manifests which will
// be walked for usage. Setting this value to 0 will require all manifests to
// be walked, returning ErrNotFound if manifests are missing.
// NOTE: By default all manifests which exist will be walked
// and any non-existent manifests and their subobjects will be ignored.
func WithUsageManifestLimit(i int) UsageOpt {
// If 0 then don't filter any manifests
// By default limits to current platform
return func(o *usageOptions) error {
o.manifestLimit = &i
return nil
}
}
// WithSnapshotUsage will check for referenced snapshots from the image objects
// and include the snapshot size in the total usage.
func WithSnapshotUsage() UsageOpt {
return func(o *usageOptions) error {
o.snapshots = true
return nil
}
}
// WithManifestUsage is used to get the usage for an image based on what is
// reported by the manifests rather than what exists in the content store.
// NOTE: This function is best used with the manifest limit set to get a
// consistent value, otherwise non-existent manifests will be excluded.
func WithManifestUsage() UsageOpt {
return func(o *usageOptions) error {
o.manifestOnly = true
return nil
}
}
var _ = (Image)(&image{})
// NewImage returns a client image object from the metadata image
func NewImage(client *Client, i images.Image) Image {
return &image{
client: client,
i: i,
platform: client.platform,
}
}
// NewImageWithPlatform returns a client image object from the metadata image
func NewImageWithPlatform(client *Client, i images.Image, platform platforms.MatchComparer) Image {
return &image{
client: client,
i: i,
platform: platform,
}
}
type image struct {
client *Client
i images.Image
platform platforms.MatchComparer
diffIDs []digest.Digest
mu sync.Mutex
}
func (i *image) Metadata() images.Image {
return i.i
}
func (i *image) Name() string {
return i.i.Name
}
func (i *image) Target() ocispec.Descriptor {
return i.i.Target
}
func (i *image) Labels() map[string]string {
return i.i.Labels
}
func (i *image) RootFS(ctx context.Context) ([]digest.Digest, error) {
i.mu.Lock()
defer i.mu.Unlock()
if i.diffIDs != nil {
return i.diffIDs, nil
}
provider := i.client.ContentStore()
diffIDs, err := i.i.RootFS(ctx, provider, i.platform)
if err != nil {
return nil, err
}
i.diffIDs = diffIDs
return diffIDs, nil
}
func (i *image) Size(ctx context.Context) (int64, error) {
return i.Usage(ctx, WithUsageManifestLimit(1), WithManifestUsage())
}
func (i *image) Usage(ctx context.Context, opts ...UsageOpt) (int64, error) {
var config usageOptions
for _, opt := range opts {
if err := opt(&config); err != nil {
return 0, err
}
}
var (
provider = i.client.ContentStore()
handler = images.ChildrenHandler(provider)
size int64
mustExist bool
)
if config.manifestLimit != nil {
handler = images.LimitManifests(handler, i.platform, *config.manifestLimit)
mustExist = true
}
var wh images.HandlerFunc = func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
var usage int64
children, err := handler(ctx, desc)
if err != nil {
if !errdefs.IsNotFound(err) || mustExist {
return nil, err
}
if !config.manifestOnly {
// Do not count size of non-existent objects
desc.Size = 0
}
} else if config.snapshots || !config.manifestOnly {
info, err := provider.Info(ctx, desc.Digest)
if err != nil {
if !errdefs.IsNotFound(err) {
return nil, err
}
if !config.manifestOnly {
// Do not count size of non-existent objects
desc.Size = 0
}
} else if info.Size > desc.Size {
// Count actual usage, Size may be unset or -1
desc.Size = info.Size
}
if config.snapshots {
for k, v := range info.Labels {
const prefix = "containerd.io/gc.ref.snapshot."
if !strings.HasPrefix(k, prefix) {
continue
}
sn := i.client.SnapshotService(k[len(prefix):])
if sn == nil {
continue
}
u, err := sn.Usage(ctx, v)
if err != nil {
if !errdefs.IsNotFound(err) && !errdefs.IsInvalidArgument(err) {
return nil, err
}
} else {
usage += u.Size
}
}
}
}
// Ignore unknown sizes. Generally unknown sizes should
// never be set in manifests, however, the usage
// calculation does not need to enforce this.
if desc.Size >= 0 {
usage += desc.Size
}
atomic.AddInt64(&size, usage)
return children, nil
}
l := semaphore.NewWeighted(3)
if err := images.Dispatch(ctx, wh, l, i.i.Target); err != nil {
return 0, err
}
return size, nil
}
func (i *image) Config(ctx context.Context) (ocispec.Descriptor, error) {
provider := i.client.ContentStore()
return i.i.Config(ctx, provider, i.platform)
}
func (i *image) IsUnpacked(ctx context.Context, snapshotterName string) (bool, error) {
sn, err := i.client.getSnapshotter(ctx, snapshotterName)
if err != nil {
return false, err
}
diffs, err := i.RootFS(ctx)
if err != nil {
return false, err
}
chainID := identity.ChainID(diffs)
_, err = sn.Stat(ctx, chainID.String())
if err == nil {
return true, nil
} else if !errdefs.IsNotFound(err) {
return false, err
}
return false, nil
}
func (i *image) Spec(ctx context.Context) (ocispec.Image, error) {
var ociImage ocispec.Image
desc, err := i.Config(ctx)
if err != nil {
return ociImage, fmt.Errorf("get image config descriptor: %w", err)
}
blob, err := content.ReadBlob(ctx, i.ContentStore(), desc)
if err != nil {
return ociImage, fmt.Errorf("read image config from content store: %w", err)
}
if err := json.Unmarshal(blob, &ociImage); err != nil {
return ociImage, fmt.Errorf("unmarshal image config %s: %w", blob, err)
}
return ociImage, nil
}
// UnpackConfig provides configuration for the unpack of an image
type UnpackConfig struct {
// ApplyOpts for applying a diff to a snapshotter
ApplyOpts []diff.ApplyOpt
// SnapshotOpts for configuring a snapshotter
SnapshotOpts []snapshots.Opt
// CheckPlatformSupported is whether to validate that a snapshotter
// supports an image's platform before unpacking
CheckPlatformSupported bool
// DuplicationSuppressor is used to make sure that there is only one
// in-flight fetch request or unpack handler for a given descriptor's
// digest or chain ID.
DuplicationSuppressor kmutex.KeyedLocker
}
// UnpackOpt provides configuration for unpack
type UnpackOpt func(context.Context, *UnpackConfig) error
// WithSnapshotterPlatformCheck sets `CheckPlatformSupported` on the UnpackConfig
func WithSnapshotterPlatformCheck() UnpackOpt {
return func(ctx context.Context, uc *UnpackConfig) error {
uc.CheckPlatformSupported = true
return nil
}
}
// WithUnpackDuplicationSuppressor sets `DuplicationSuppressor` on the UnpackConfig.
func WithUnpackDuplicationSuppressor(suppressor kmutex.KeyedLocker) UnpackOpt {
return func(ctx context.Context, uc *UnpackConfig) error {
uc.DuplicationSuppressor = suppressor
return nil
}
}
func (i *image) Unpack(ctx context.Context, snapshotterName string, opts ...UnpackOpt) error {
ctx, done, err := i.client.WithLease(ctx)
if err != nil {
return err
}
defer done(ctx)
var config UnpackConfig
for _, o := range opts {
if err := o(ctx, &config); err != nil {
return err
}
}
manifest, err := i.getManifest(ctx, i.platform)
if err != nil {
return err
}
layers, err := i.getLayers(ctx, manifest)
if err != nil {
return err
}
var (
a = i.client.DiffService()
cs = i.client.ContentStore()
chain []digest.Digest
unpacked bool
)
snapshotterName, err = i.client.resolveSnapshotterName(ctx, snapshotterName)
if err != nil {
return err
}
sn, err := i.client.getSnapshotter(ctx, snapshotterName)
if err != nil {
return err
}
if config.CheckPlatformSupported {
if err := i.checkSnapshotterSupport(ctx, snapshotterName, manifest); err != nil {
return err
}
}
for _, layer := range layers {
unpacked, err = rootfs.ApplyLayerWithOpts(ctx, layer, chain, sn, a, config.SnapshotOpts, config.ApplyOpts)
if err != nil {
return err
}
if unpacked {
// Set the uncompressed label after the uncompressed
// digest has been verified through apply.
cinfo := content.Info{
Digest: layer.Blob.Digest,
Labels: map[string]string{
labels.LabelUncompressed: layer.Diff.Digest.String(),
},
}
if _, err := cs.Update(ctx, cinfo, "labels."+labels.LabelUncompressed); err != nil {
return err
}
}
chain = append(chain, layer.Diff.Digest)
}
desc, err := i.i.Config(ctx, cs, i.platform)
if err != nil {
return err
}
rootfs := identity.ChainID(chain).String()
cinfo := content.Info{
Digest: desc.Digest,
Labels: map[string]string{
fmt.Sprintf("containerd.io/gc.ref.snapshot.%s", snapshotterName): rootfs,
},
}
_, err = cs.Update(ctx, cinfo, fmt.Sprintf("labels.containerd.io/gc.ref.snapshot.%s", snapshotterName))
return err
}
func (i *image) getManifest(ctx context.Context, platform platforms.MatchComparer) (ocispec.Manifest, error) {
cs := i.ContentStore()
manifest, err := images.Manifest(ctx, cs, i.i.Target, platform)
if err != nil {
return ocispec.Manifest{}, err
}
return manifest, nil
}
func (i *image) getLayers(ctx context.Context, manifest ocispec.Manifest) ([]rootfs.Layer, error) {
diffIDs, err := i.RootFS(ctx)
if err != nil {
return nil, fmt.Errorf("failed to resolve rootfs: %w", err)
}
if len(diffIDs) != len(manifest.Layers) {
return nil, errors.New("mismatched image rootfs and manifest layers")
}
layers := make([]rootfs.Layer, len(diffIDs))
for i := range diffIDs {
layers[i].Diff = ocispec.Descriptor{
// TODO: derive media type from compressed type
MediaType: ocispec.MediaTypeImageLayer,
Digest: diffIDs[i],
}
layers[i].Blob = manifest.Layers[i]
}
return layers, nil
}
func (i *image) getManifestPlatform(ctx context.Context, manifest ocispec.Manifest) (ocispec.Platform, error) {
cs := i.ContentStore()
p, err := content.ReadBlob(ctx, cs, manifest.Config)
if err != nil {
return ocispec.Platform{}, err
}
var image ocispec.Image
if err := json.Unmarshal(p, &image); err != nil {
return ocispec.Platform{}, err
}
return platforms.Normalize(ocispec.Platform{OS: image.OS, Architecture: image.Architecture}), nil
}
func (i *image) checkSnapshotterSupport(ctx context.Context, snapshotterName string, manifest ocispec.Manifest) error {
snapshotterPlatformMatcher, err := i.client.GetSnapshotterSupportedPlatforms(ctx, snapshotterName)
if err != nil {
return err
}
manifestPlatform, err := i.getManifestPlatform(ctx, manifest)
if err != nil {
return err
}
if snapshotterPlatformMatcher.Match(manifestPlatform) {
return nil
}
return fmt.Errorf("snapshotter %s does not support platform %s for image %s", snapshotterName, manifestPlatform, manifest.Config.Digest)
}
func (i *image) ContentStore() content.Store {
return i.client.ContentStore()
}
func (i *image) Platform() platforms.MatchComparer {
return i.platform
}