reference_builder.go

Documentation: github.com/docker/distribution/manifest/schema1

     1  package schema1
     2  
     3  import (
     4  	"context"
     5  	"errors"
     6  	"fmt"
     7  
     8  	"github.com/distribution/reference"
     9  	"github.com/docker/distribution"
    10  	"github.com/docker/distribution/manifest"
    11  	"github.com/docker/libtrust"
    12  	"github.com/opencontainers/go-digest"
    13  )
    14  
    15  // referenceManifestBuilder is a type for constructing manifests from schema1
    16  // dependencies.
    17  type referenceManifestBuilder struct {
    18  	Manifest
    19  	pk libtrust.PrivateKey
    20  }
    21  
    22  // NewReferenceManifestBuilder is used to build new manifests for the current
    23  // schema version using schema1 dependencies.
    24  func NewReferenceManifestBuilder(pk libtrust.PrivateKey, ref reference.Named, architecture string) distribution.ManifestBuilder {
    25  	tag := ""
    26  	if tagged, isTagged := ref.(reference.Tagged); isTagged {
    27  		tag = tagged.Tag()
    28  	}
    29  
    30  	return &referenceManifestBuilder{
    31  		Manifest: Manifest{
    32  			Versioned: manifest.Versioned{
    33  				SchemaVersion: 1,
    34  			},
    35  			Name:         ref.Name(),
    36  			Tag:          tag,
    37  			Architecture: architecture,
    38  		},
    39  		pk: pk,
    40  	}
    41  }
    42  
    43  func (mb *referenceManifestBuilder) Build(ctx context.Context) (distribution.Manifest, error) {
    44  	m := mb.Manifest
    45  	if len(m.FSLayers) == 0 {
    46  		return nil, errors.New("cannot build manifest with zero layers or history")
    47  	}
    48  
    49  	m.FSLayers = make([]FSLayer, len(mb.Manifest.FSLayers))
    50  	m.History = make([]History, len(mb.Manifest.History))
    51  	copy(m.FSLayers, mb.Manifest.FSLayers)
    52  	copy(m.History, mb.Manifest.History)
    53  
    54  	return Sign(&m, mb.pk)
    55  }
    56  
    57  // AppendReference adds a reference to the current ManifestBuilder
    58  func (mb *referenceManifestBuilder) AppendReference(d distribution.Describable) error {
    59  	r, ok := d.(Reference)
    60  	if !ok {
    61  		return fmt.Errorf("unable to add non-reference type to v1 builder")
    62  	}
    63  
    64  	// Entries need to be prepended
    65  	mb.Manifest.FSLayers = append([]FSLayer{{BlobSum: r.Digest}}, mb.Manifest.FSLayers...)
    66  	mb.Manifest.History = append([]History{r.History}, mb.Manifest.History...)
    67  	return nil
    68  
    69  }
    70  
    71  // References returns the current references added to this builder
    72  func (mb *referenceManifestBuilder) References() []distribution.Descriptor {
    73  	refs := make([]distribution.Descriptor, len(mb.Manifest.FSLayers))
    74  	for i := range mb.Manifest.FSLayers {
    75  		layerDigest := mb.Manifest.FSLayers[i].BlobSum
    76  		history := mb.Manifest.History[i]
    77  		ref := Reference{layerDigest, 0, history}
    78  		refs[i] = ref.Descriptor()
    79  	}
    80  	return refs
    81  }
    82  
    83  // Reference describes a manifest v2, schema version 1 dependency.
    84  // An FSLayer associated with a history entry.
    85  type Reference struct {
    86  	Digest  digest.Digest
    87  	Size    int64 // if we know it, set it for the descriptor.
    88  	History History
    89  }
    90  
    91  // Descriptor describes a reference
    92  func (r Reference) Descriptor() distribution.Descriptor {
    93  	return distribution.Descriptor{
    94  		MediaType: MediaTypeManifestLayer,
    95  		Digest:    r.Digest,
    96  		Size:      r.Size,
    97  	}
    98  }
    99
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