index.go

Documentation: github.com/google/go-containerregistry/pkg/v1/partial

     1  // Copyright 2020 Google LLC All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //    http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package partial
    16  
    17  import (
    18  	"fmt"
    19  
    20  	v1 "github.com/google/go-containerregistry/pkg/v1"
    21  	"github.com/google/go-containerregistry/pkg/v1/match"
    22  	"github.com/google/go-containerregistry/pkg/v1/types"
    23  )
    24  
    25  // FindManifests given a v1.ImageIndex, find the manifests that fit the matcher.
    26  func FindManifests(index v1.ImageIndex, matcher match.Matcher) ([]v1.Descriptor, error) {
    27  	// get the actual manifest list
    28  	indexManifest, err := index.IndexManifest()
    29  	if err != nil {
    30  		return nil, fmt.Errorf("unable to get raw index: %w", err)
    31  	}
    32  	manifests := []v1.Descriptor{}
    33  	// try to get the root of our image
    34  	for _, manifest := range indexManifest.Manifests {
    35  		if matcher(manifest) {
    36  			manifests = append(manifests, manifest)
    37  		}
    38  	}
    39  	return manifests, nil
    40  }
    41  
    42  // FindImages given a v1.ImageIndex, find the images that fit the matcher. If a Descriptor
    43  // matches the provider Matcher, but the referenced item is not an Image, ignores it.
    44  // Only returns those that match the Matcher and are images.
    45  func FindImages(index v1.ImageIndex, matcher match.Matcher) ([]v1.Image, error) {
    46  	matches := []v1.Image{}
    47  	manifests, err := FindManifests(index, matcher)
    48  	if err != nil {
    49  		return nil, err
    50  	}
    51  	for _, desc := range manifests {
    52  		// if it is not an image, ignore it
    53  		if !desc.MediaType.IsImage() {
    54  			continue
    55  		}
    56  		img, err := index.Image(desc.Digest)
    57  		if err != nil {
    58  			return nil, err
    59  		}
    60  		matches = append(matches, img)
    61  	}
    62  	return matches, nil
    63  }
    64  
    65  // FindIndexes given a v1.ImageIndex, find the indexes that fit the matcher. If a Descriptor
    66  // matches the provider Matcher, but the referenced item is not an Index, ignores it.
    67  // Only returns those that match the Matcher and are indexes.
    68  func FindIndexes(index v1.ImageIndex, matcher match.Matcher) ([]v1.ImageIndex, error) {
    69  	matches := []v1.ImageIndex{}
    70  	manifests, err := FindManifests(index, matcher)
    71  	if err != nil {
    72  		return nil, err
    73  	}
    74  	for _, desc := range manifests {
    75  		if !desc.MediaType.IsIndex() {
    76  			continue
    77  		}
    78  		// if it is not an index, ignore it
    79  		idx, err := index.ImageIndex(desc.Digest)
    80  		if err != nil {
    81  			return nil, err
    82  		}
    83  		matches = append(matches, idx)
    84  	}
    85  	return matches, nil
    86  }
    87  
    88  type withManifests interface {
    89  	Manifests() ([]Describable, error)
    90  }
    91  
    92  type withLayer interface {
    93  	Layer(v1.Hash) (v1.Layer, error)
    94  }
    95  
    96  type describable struct {
    97  	desc v1.Descriptor
    98  }
    99  
   100  func (d describable) Digest() (v1.Hash, error) {
   101  	return d.desc.Digest, nil
   102  }
   103  
   104  func (d describable) Size() (int64, error) {
   105  	return d.desc.Size, nil
   106  }
   107  
   108  func (d describable) MediaType() (types.MediaType, error) {
   109  	return d.desc.MediaType, nil
   110  }
   111  
   112  func (d describable) Descriptor() (*v1.Descriptor, error) {
   113  	return &d.desc, nil
   114  }
   115  
   116  // Manifests is analogous to v1.Image.Layers in that it allows values in the
   117  // returned list to be lazily evaluated, which enables an index to contain
   118  // an image that contains a streaming layer.
   119  //
   120  // This should have been part of the v1.ImageIndex interface, but wasn't.
   121  // It is instead usable through this extension interface.
   122  func Manifests(idx v1.ImageIndex) ([]Describable, error) {
   123  	if wm, ok := idx.(withManifests); ok {
   124  		return wm.Manifests()
   125  	}
   126  
   127  	return ComputeManifests(idx)
   128  }
   129  
   130  // ComputeManifests provides a fallback implementation for Manifests.
   131  func ComputeManifests(idx v1.ImageIndex) ([]Describable, error) {
   132  	m, err := idx.IndexManifest()
   133  	if err != nil {
   134  		return nil, err
   135  	}
   136  	manifests := []Describable{}
   137  	for _, desc := range m.Manifests {
   138  		switch {
   139  		case desc.MediaType.IsImage():
   140  			img, err := idx.Image(desc.Digest)
   141  			if err != nil {
   142  				return nil, err
   143  			}
   144  			manifests = append(manifests, img)
   145  		case desc.MediaType.IsIndex():
   146  			idx, err := idx.ImageIndex(desc.Digest)
   147  			if err != nil {
   148  				return nil, err
   149  			}
   150  			manifests = append(manifests, idx)
   151  		default:
   152  			if wl, ok := idx.(withLayer); ok {
   153  				layer, err := wl.Layer(desc.Digest)
   154  				if err != nil {
   155  					return nil, err
   156  				}
   157  				manifests = append(manifests, layer)
   158  			} else {
   159  				manifests = append(manifests, describable{desc})
   160  			}
   161  		}
   162  	}
   163  
   164  	return manifests, nil
   165  }
   166
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