gc.go

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

     1  // Copyright 2018 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  // This is an EXPERIMENTAL package, and may change in arbitrary ways without notice.
    16  package layout
    17  
    18  import (
    19  	"fmt"
    20  	"io/fs"
    21  	"path/filepath"
    22  	"strings"
    23  
    24  	v1 "github.com/google/go-containerregistry/pkg/v1"
    25  )
    26  
    27  // GarbageCollect removes unreferenced blobs from the oci-layout
    28  //
    29  //	This is an experimental api, and not subject to any stability guarantees
    30  //	We may abandon it at any time, without prior notice.
    31  //	Deprecated: Use it at your own risk!
    32  func (l Path) GarbageCollect() ([]v1.Hash, error) {
    33  	idx, err := l.ImageIndex()
    34  	if err != nil {
    35  		return nil, err
    36  	}
    37  	blobsToKeep := map[string]bool{}
    38  	if err := l.garbageCollectImageIndex(idx, blobsToKeep); err != nil {
    39  		return nil, err
    40  	}
    41  	blobsDir := l.path("blobs")
    42  	removedBlobs := []v1.Hash{}
    43  
    44  	err = filepath.WalkDir(blobsDir, func(path string, d fs.DirEntry, err error) error {
    45  		if err != nil {
    46  			return err
    47  		}
    48  
    49  		if d.IsDir() {
    50  			return nil
    51  		}
    52  
    53  		rel, err := filepath.Rel(blobsDir, path)
    54  		if err != nil {
    55  			return err
    56  		}
    57  		hashString := strings.Replace(rel, "/", ":", 1)
    58  		if present := blobsToKeep[hashString]; !present {
    59  			h, err := v1.NewHash(hashString)
    60  			if err != nil {
    61  				return err
    62  			}
    63  			removedBlobs = append(removedBlobs, h)
    64  		}
    65  		return nil
    66  	})
    67  
    68  	if err != nil {
    69  		return nil, err
    70  	}
    71  
    72  	return removedBlobs, nil
    73  }
    74  
    75  func (l Path) garbageCollectImageIndex(index v1.ImageIndex, blobsToKeep map[string]bool) error {
    76  	idxm, err := index.IndexManifest()
    77  	if err != nil {
    78  		return err
    79  	}
    80  
    81  	h, err := index.Digest()
    82  	if err != nil {
    83  		return err
    84  	}
    85  
    86  	blobsToKeep[h.String()] = true
    87  
    88  	for _, descriptor := range idxm.Manifests {
    89  		if descriptor.MediaType.IsImage() {
    90  			img, err := index.Image(descriptor.Digest)
    91  			if err != nil {
    92  				return err
    93  			}
    94  			if err := l.garbageCollectImage(img, blobsToKeep); err != nil {
    95  				return err
    96  			}
    97  		} else if descriptor.MediaType.IsIndex() {
    98  			idx, err := index.ImageIndex(descriptor.Digest)
    99  			if err != nil {
   100  				return err
   101  			}
   102  			if err := l.garbageCollectImageIndex(idx, blobsToKeep); err != nil {
   103  				return err
   104  			}
   105  		} else {
   106  			return fmt.Errorf("gc: unknown media type: %s", descriptor.MediaType)
   107  		}
   108  	}
   109  	return nil
   110  }
   111  
   112  func (l Path) garbageCollectImage(image v1.Image, blobsToKeep map[string]bool) error {
   113  	h, err := image.Digest()
   114  	if err != nil {
   115  		return err
   116  	}
   117  	blobsToKeep[h.String()] = true
   118  
   119  	h, err = image.ConfigName()
   120  	if err != nil {
   121  		return err
   122  	}
   123  	blobsToKeep[h.String()] = true
   124  
   125  	ls, err := image.Layers()
   126  	if err != nil {
   127  		return err
   128  	}
   129  	for _, l := range ls {
   130  		h, err := l.Digest()
   131  		if err != nil {
   132  			return err
   133  		}
   134  		blobsToKeep[h.String()] = true
   135  	}
   136  	return nil
   137  }
   138
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