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local.go
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local.go
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package local
import (
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/buildpacks/imgutil"
)
// Image wraps an imgutil.CNBImageCore and implements the methods needed to complete the imgutil.Image interface.
type Image struct {
*imgutil.CNBImageCore
repoName string
store *Store
lastIdentifier string
daemonOS string
}
func (i *Image) Kind() string {
return "local"
}
func (i *Image) Name() string {
return i.repoName
}
func (i *Image) Rename(name string) {
i.repoName = name
}
func (i *Image) Found() bool {
return i.lastIdentifier != ""
}
func (i *Image) Identifier() (imgutil.Identifier, error) {
return IDIdentifier{
ImageID: strings.TrimPrefix(i.lastIdentifier, "sha256:"),
}, nil
}
func (i *Image) Valid() bool {
// local images are actually always invalid, because they are missing a manifest, but let's ignore that for now
return true
}
// GetLayer returns an io.ReadCloser with uncompressed layer data.
// The layer will always have data, even if that means downloading ALL the image layers from the daemon.
func (i *Image) GetLayer(diffID string) (io.ReadCloser, error) {
layerHash, err := v1.NewHash(diffID)
if err != nil {
return nil, err
}
configFile, err := i.ConfigFile()
if err != nil {
return nil, err
}
if !contains(configFile.RootFS.DiffIDs, layerHash) {
return nil, imgutil.ErrLayerNotFound{DiffID: layerHash.String()}
}
layer, err := i.LayerByDiffID(layerHash)
if err == nil {
// this avoids downloading ALL the image layers from the daemon
// if the layer is available locally
// (e.g., it was added using AddLayer).
if size, err := layer.Size(); err != nil && size != -1 {
return layer.Uncompressed()
}
}
if err = i.ensureLayers(); err != nil {
return nil, err
}
layer, err = i.LayerByDiffID(layerHash)
if err != nil {
return nil, err
}
return layer.Uncompressed()
}
func contains(diffIDs []v1.Hash, hash v1.Hash) bool {
for _, diffID := range diffIDs {
if diffID.String() == hash.String() {
return true
}
}
return false
}
func (i *Image) ensureLayers() error {
if err := i.store.downloadLayersFor(i.lastIdentifier); err != nil {
return fmt.Errorf("failed to fetch base layers: %w", err)
}
return nil
}
func (i *Image) SetOS(osVal string) error {
if osVal != i.daemonOS {
return errors.New("invalid os: must match the daemon")
}
return i.CNBImageCore.SetOS(osVal)
}
var emptyHistory = v1.History{Created: v1.Time{Time: imgutil.NormalizedDateTime}}
func (i *Image) AddLayer(path string) error {
diffID, err := calculateChecksum(path)
if err != nil {
return err
}
layer, err := i.addLayerToStore(path, diffID)
if err != nil {
return err
}
return i.AddLayerWithHistory(layer, emptyHistory)
}
func calculateChecksum(path string) (string, error) {
f, err := os.Open(filepath.Clean(path))
if err != nil {
return "", fmt.Errorf("failed to open layer at path %s: %w", path, err)
}
defer f.Close()
hasher := sha256.New()
if _, err := io.Copy(hasher, f); err != nil {
return "", fmt.Errorf("failed to calculate checksum for layer at path %s: %w", path, err)
}
return "sha256:" + hex.EncodeToString(hasher.Sum(make([]byte, 0, hasher.Size()))), nil
}
func (i *Image) AddLayerWithDiffID(path, diffID string) error {
layer, err := i.addLayerToStore(path, diffID)
if err != nil {
return err
}
return i.AddLayerWithHistory(layer, emptyHistory)
}
func (i *Image) AddLayerWithDiffIDAndHistory(path, diffID string, history v1.History) error {
layer, err := i.addLayerToStore(path, diffID)
if err != nil {
return err
}
return i.AddLayerWithHistory(layer, history)
}
func (i *Image) addLayerToStore(fromPath, withDiffID string) (v1.Layer, error) {
var (
layer v1.Layer
err error
)
diffID, err := v1.NewHash(withDiffID)
if err != nil {
return nil, err
}
layer = newPopulatedLayer(diffID, fromPath, 1)
if err != nil {
return nil, err
}
fi, err := os.Stat(fromPath)
if err != nil {
return nil, err
}
i.store.AddLayer(layer, diffID, fi.Size())
return layer, nil
}
func (i *Image) AddOrReuseLayerWithHistory(path string, diffID string, history v1.History) error {
prevLayerExists, err := i.PreviousImageHasLayer(diffID)
if err != nil {
return err
}
if !prevLayerExists {
return i.AddLayerWithDiffIDAndHistory(path, diffID, history)
}
return i.ReuseLayerWithHistory(diffID, history)
}
func (i *Image) Rebase(baseTopLayerDiffID string, withNewBase imgutil.Image) error {
if err := i.ensureLayers(); err != nil {
return err
}
return i.CNBImageCore.Rebase(baseTopLayerDiffID, withNewBase)
}
func (i *Image) Save(additionalNames ...string) error {
err := i.SetCreatedAtAndHistory()
if err != nil {
return err
}
i.lastIdentifier, err = i.store.Save(i, i.Name(), additionalNames...)
return err
}
func (i *Image) SaveAs(name string, additionalNames ...string) error {
err := i.SetCreatedAtAndHistory()
if err != nil {
return err
}
i.lastIdentifier, err = i.store.Save(i, name, additionalNames...)
return err
}
func (i *Image) SaveFile() (string, error) {
return i.store.SaveFile(i, i.Name())
}
func (i *Image) Delete() error {
return i.store.Delete(i.lastIdentifier)
}