88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
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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