images: move image package to images
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This commit is contained in:
Stephen J Day
parent
604af9cd46
commit
39da6ff879
10 changed files with 28 additions and 28 deletions
154
images/handlers.go
Normal file
154
images/handlers.go
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@ -0,0 +1,154 @@
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package images
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import (
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"context"
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"encoding/json"
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"fmt"
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"github.com/docker/containerd/content"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/pkg/errors"
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"golang.org/x/sync/errgroup"
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)
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const (
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MediaTypeDockerSchema2Layer = "application/vnd.docker.image.rootfs.diff.tar"
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MediaTypeDockerSchema2LayerGzip = "application/vnd.docker.image.rootfs.diff.tar.gzip"
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MediaTypeDockerSchema2Config = "application/vnd.docker.container.image.v1+json"
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MediaTypeDockerSchema2Manifest = "application/vnd.docker.distribution.manifest.v2+json"
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MediaTypeDockerSchema2ManifestList = "application/vnd.docker.distribution.manifest.list.v2+json"
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)
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var SkipDesc = fmt.Errorf("skip descriptor")
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type Handler interface {
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Handle(ctx context.Context, desc ocispec.Descriptor) (subdescs []ocispec.Descriptor, err error)
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}
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type HandlerFunc func(ctx context.Context, desc ocispec.Descriptor) (subdescs []ocispec.Descriptor, err error)
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func (fn HandlerFunc) Handle(ctx context.Context, desc ocispec.Descriptor) (subdescs []ocispec.Descriptor, err error) {
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return fn(ctx, desc)
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}
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// Handlers returns a handler that will run the handlers in sequence.
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func Handlers(handlers ...Handler) HandlerFunc {
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return func(ctx context.Context, desc ocispec.Descriptor) (subdescs []ocispec.Descriptor, err error) {
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var children []ocispec.Descriptor
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for _, handler := range handlers {
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ch, err := handler.Handle(ctx, desc)
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if err != nil {
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return nil, err
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}
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children = append(children, ch...)
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}
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return children, nil
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}
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}
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// Walk the resources of an image and call the handler for each. If the handler
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// decodes the sub-resources for each image,
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//
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// This differs from dispatch in that each sibling resource is considered
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// synchronously.
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func Walk(ctx context.Context, handler Handler, descs ...ocispec.Descriptor) error {
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for _, desc := range descs {
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children, err := handler.Handle(ctx, desc)
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if err != nil {
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if errors.Cause(err) == SkipDesc {
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return nil // don't traverse the children.
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}
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return err
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}
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if len(children) > 0 {
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if err := Walk(ctx, handler, children...); err != nil {
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return err
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}
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}
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}
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return nil
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}
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// Dispatch runs the provided handler for content specified by the descriptors.
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// If the handler decode subresources, they will be visited, as well.
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//
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// Handlers for siblings are run in parallel on the provided descriptors. A
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// handler may return `SkipDesc` to signal to the dispatcher to not traverse
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// any children.
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//
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// Typically, this function will be used with `FetchHandler`, often composed
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// with other handlers.
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//
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// If any handler returns an error, the dispatch session will be canceled.
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func Dispatch(ctx context.Context, handler Handler, descs ...ocispec.Descriptor) error {
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eg, ctx := errgroup.WithContext(ctx)
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for _, desc := range descs {
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desc := desc
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eg.Go(func() error {
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desc := desc
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children, err := handler.Handle(ctx, desc)
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if err != nil {
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if errors.Cause(err) == SkipDesc {
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return nil // don't traverse the children.
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}
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return err
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}
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if len(children) > 0 {
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return Dispatch(ctx, handler, children...)
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}
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return nil
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})
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}
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return eg.Wait()
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}
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// ChildrenHandler decodes well-known manifests types and returns their children.
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//
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// This is useful for supporting recursive fetch and other use cases where you
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// want to do a full walk of resources.
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//
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// One can also replace this with another implementation to allow descending of
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// arbitrary types.
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func ChildrenHandler(provider content.Provider) HandlerFunc {
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return func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
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switch desc.MediaType {
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case MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
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case MediaTypeDockerSchema2Layer, MediaTypeDockerSchema2LayerGzip,
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MediaTypeDockerSchema2Config:
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return nil, nil
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default:
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return nil, fmt.Errorf("%v not yet supported", desc.MediaType)
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}
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p, err := content.ReadBlob(ctx, provider, desc.Digest)
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if err != nil {
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return nil, err
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}
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// TODO(stevvooe): We just assume oci manifest, for now. There may be
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// subtle differences from the docker version.
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var manifest ocispec.Manifest
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if err := json.Unmarshal(p, &manifest); err != nil {
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return nil, err
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}
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var descs []ocispec.Descriptor
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descs = append(descs, manifest.Config)
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for _, desc := range manifest.Layers {
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descs = append(descs, desc)
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}
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return descs, nil
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}
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}
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88
images/image.go
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88
images/image.go
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@ -0,0 +1,88 @@
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package images
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import (
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"context"
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"encoding/json"
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"errors"
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"io/ioutil"
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"github.com/docker/containerd/content"
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"github.com/docker/containerd/log"
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digest "github.com/opencontainers/go-digest"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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)
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// Image provides the model for how containerd views container images.
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type Image struct {
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Name string
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Descriptor ocispec.Descriptor
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}
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// TODO(stevvooe): Many of these functions make strong platform assumptions,
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// which are untrue in a lot of cases. More refactoring must be done here to
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// make this work in all cases.
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// Config resolves the image configuration descriptor.
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//
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// The caller can then use the descriptor to resolve and process the
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// configuration of the image.
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func (image *Image) Config(ctx context.Context, provider content.Provider) (ocispec.Descriptor, error) {
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var configDesc ocispec.Descriptor
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return configDesc, Walk(ctx, HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
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switch image.Descriptor.MediaType {
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case MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
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rc, err := provider.Reader(ctx, image.Descriptor.Digest)
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if err != nil {
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return nil, err
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}
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defer rc.Close()
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p, err := ioutil.ReadAll(rc)
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if err != nil {
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return nil, err
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}
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var manifest ocispec.Manifest
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if err := json.Unmarshal(p, &manifest); err != nil {
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return nil, err
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}
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configDesc = manifest.Config
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return nil, nil
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default:
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return nil, errors.New("could not resolve config")
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}
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}), image.Descriptor)
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}
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// RootFS returns the unpacked diffids that make up and images rootfs.
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//
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// These are used to verify that a set of layers unpacked to the expected
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// values.
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func (image *Image) RootFS(ctx context.Context, provider content.Provider) ([]digest.Digest, error) {
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desc, err := image.Config(ctx, provider)
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if err != nil {
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return nil, err
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}
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p, err := content.ReadBlob(ctx, provider, desc.Digest)
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if err != nil {
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log.G(ctx).Fatal(err)
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}
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var config ocispec.Image
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if err := json.Unmarshal(p, &config); err != nil {
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log.G(ctx).Fatal(err)
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}
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// TODO(stevvooe): Remove this bit when OCI structure uses correct type for
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// rootfs.DiffIDs.
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var diffIDs []digest.Digest
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for _, diffID := range config.RootFS.DiffIDs {
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diffIDs = append(diffIDs, digest.Digest(diffID))
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}
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return diffIDs, nil
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}
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181
images/storage.go
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181
images/storage.go
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package images
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import (
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"encoding/binary"
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"fmt"
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"github.com/boltdb/bolt"
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"github.com/docker/containerd/log"
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digest "github.com/opencontainers/go-digest"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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)
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var (
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errImageUnknown = fmt.Errorf("image: unknown")
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errNoTx = fmt.Errorf("no transaction available")
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)
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var (
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bucketKeyStorageVersion = []byte("v1")
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bucketKeyImages = []byte("images")
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bucketKeyDigest = []byte("digest")
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bucketKeyMediaType = []byte("mediatype")
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bucketKeySize = []byte("size")
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)
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// TODO(stevvooe): This file comprises the data required to implement the
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// "metadata" store. For now, it is bound tightly to the local machine and bolt
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// but we can take this and use it to define a service interface.
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func InitDB(db *bolt.DB) error {
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log.L.Debug("init db")
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return db.Update(func(tx *bolt.Tx) error {
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_, err := createBucketIfNotExists(tx, bucketKeyStorageVersion, bucketKeyImages)
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return err
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})
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}
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func Register(tx *bolt.Tx, name string, desc ocispec.Descriptor) error {
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return withImagesBucket(tx, func(bkt *bolt.Bucket) error {
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ibkt, err := bkt.CreateBucketIfNotExists([]byte(name))
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if err != nil {
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return err
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}
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var (
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buf [binary.MaxVarintLen64]byte
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sizeEncoded []byte = buf[:]
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)
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sizeEncoded = sizeEncoded[:binary.PutVarint(sizeEncoded, desc.Size)]
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if len(sizeEncoded) == 0 {
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return fmt.Errorf("failed encoding size = %v", desc.Size)
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}
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for _, v := range [][2][]byte{
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{bucketKeyDigest, []byte(desc.Digest)},
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{bucketKeyMediaType, []byte(desc.MediaType)},
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{bucketKeySize, sizeEncoded},
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} {
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if err := ibkt.Put(v[0], v[1]); err != nil {
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return err
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}
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}
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return nil
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})
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}
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func Get(tx *bolt.Tx, name string) (Image, error) {
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var image Image
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if err := withImageBucket(tx, name, func(bkt *bolt.Bucket) error {
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image.Name = name
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return readImage(&image, bkt)
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}); err != nil {
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return Image{}, err
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}
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return image, nil
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}
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func List(tx *bolt.Tx) ([]Image, error) {
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var images []Image
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if err := withImagesBucket(tx, func(bkt *bolt.Bucket) error {
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return bkt.ForEach(func(k, v []byte) error {
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var (
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image = Image{
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Name: string(k),
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}
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kbkt = bkt.Bucket(k)
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)
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if err := readImage(&image, kbkt); err != nil {
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return err
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}
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images = append(images, image)
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return nil
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})
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}); err != nil {
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return nil, err
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}
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return images, nil
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}
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func readImage(image *Image, bkt *bolt.Bucket) error {
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return bkt.ForEach(func(k, v []byte) error {
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if v == nil {
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return nil // skip it? a bkt maybe?
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}
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// TODO(stevvooe): This is why we need to use byte values for
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// keys, rather than full arrays.
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switch string(k) {
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case string(bucketKeyDigest):
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image.Descriptor.Digest = digest.Digest(v)
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case string(bucketKeyMediaType):
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image.Descriptor.MediaType = string(v)
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case string(bucketKeySize):
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image.Descriptor.Size, _ = binary.Varint(v)
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}
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return nil
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})
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}
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func createBucketIfNotExists(tx *bolt.Tx, keys ...[]byte) (*bolt.Bucket, error) {
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bkt, err := tx.CreateBucketIfNotExists(keys[0])
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if err != nil {
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return nil, err
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}
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for _, key := range keys[1:] {
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bkt, err = bkt.CreateBucketIfNotExists(key)
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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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return bkt, nil
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}
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func withImagesBucket(tx *bolt.Tx, fn func(bkt *bolt.Bucket) error) error {
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bkt := getImagesBucket(tx)
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if bkt == nil {
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return errImageUnknown
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}
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return fn(bkt)
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}
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func withImageBucket(tx *bolt.Tx, name string, fn func(bkt *bolt.Bucket) error) error {
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bkt := getImageBucket(tx, name)
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if bkt == nil {
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return errImageUnknown
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}
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return fn(bkt)
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}
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func getImagesBucket(tx *bolt.Tx) *bolt.Bucket {
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return getBucket(tx, bucketKeyStorageVersion, bucketKeyImages)
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}
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func getImageBucket(tx *bolt.Tx, name string) *bolt.Bucket {
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return getBucket(tx, bucketKeyStorageVersion, bucketKeyImages, []byte(name))
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}
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func getBucket(tx *bolt.Tx, keys ...[]byte) *bolt.Bucket {
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bkt := tx.Bucket(keys[0])
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for _, key := range keys[1:] {
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if bkt == nil {
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break
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}
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bkt = bkt.Bucket(key)
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}
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return bkt
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}
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