/
main.go
88 lines (72 loc) · 1.29 KB
/
main.go
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package main
import (
"context"
"fmt"
"io"
"log"
"os"
"sync"
"github.com/containerd/stargz-snapshotter/estargz"
"golang.org/x/sync/errgroup"
"github.com/knqyf263/stargz-registry/remote"
)
func main() {
if err := run(); err != nil {
log.Fatal(err)
}
}
func run() error {
args := os.Args
if len(args) != 3 {
fmt.Println("Usage: ecrane IMAGE_NAME FILE_PATH")
return nil
}
var (
imageName = args[1]
filePath = args[2]
)
ctx := context.Background()
r, err := remote.New(imageName)
if err != nil {
return err
}
layers, err := r.Layers(ctx)
if err != nil {
return err
}
var result sync.Map
g, ctx := errgroup.WithContext(ctx)
for _, layer := range layers {
l := layer
g.Go(func() error {
sr := io.NewSectionReader(l, 0, l.Size())
esgz, err := estargz.Open(sr)
if err != nil {
return err
}
if e, ok := esgz.Lookup(filePath); ok {
sr, err = esgz.OpenFile(e.Name)
if err != nil {
return err
}
b, err := io.ReadAll(sr)
if err != nil {
return err
}
result.Store(layer.Digest(), b)
}
return nil
})
}
if err = g.Wait(); err != nil {
return err
}
for i := len(layers) - 1; i >= 0; i-- {
v, ok := result.Load(layers[i].Digest())
if !ok {
continue
}
fmt.Println(string(v.([]byte)))
}
return nil
}