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83 lines
2.4 KiB
Go
83 lines
2.4 KiB
Go
package imgworker
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// FROM Slightly adapted from genuinetools/img worker
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import (
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"errors"
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"fmt"
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"os"
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"github.com/containerd/containerd/content"
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"github.com/containerd/containerd/images"
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"github.com/containerd/containerd/platforms"
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"github.com/docker/distribution/reference"
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"github.com/docker/docker/pkg/archive"
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"github.com/sirupsen/logrus"
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)
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// TODO: this requires root permissions to mount/unmount layers, althrought it shouldn't be required.
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// See how backends are unpacking images without asking for root permissions.
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// Unpack exports an image to a rootfs destination directory.
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func (c *Client) Unpack(image, dest string) error {
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ctx := c.ctx
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if len(dest) < 1 {
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return errors.New("destination directory for rootfs cannot be empty")
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}
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if _, err := os.Stat(dest); err == nil {
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return fmt.Errorf("destination directory already exists: %s", dest)
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}
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// Parse the image name and tag.
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named, err := reference.ParseNormalizedNamed(image)
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if err != nil {
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return fmt.Errorf("parsing image name %q failed: %v", image, err)
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}
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// Add the latest lag if they did not provide one.
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named = reference.TagNameOnly(named)
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image = named.String()
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// Create the worker opts.
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opt, err := c.createWorkerOpt()
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if err != nil {
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return fmt.Errorf("creating worker opt failed: %v", err)
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}
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if opt.ImageStore == nil {
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return errors.New("image store is nil")
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}
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img, err := opt.ImageStore.Get(ctx, image)
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if err != nil {
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return fmt.Errorf("getting image %s from image store failed: %v", image, err)
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}
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manifest, err := images.Manifest(ctx, opt.ContentStore, img.Target, platforms.Default())
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if err != nil {
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return fmt.Errorf("getting image manifest failed: %v", err)
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}
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for _, desc := range manifest.Layers {
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logrus.Debugf("Unpacking layer %s", desc.Digest.String())
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// Read the blob from the content store.
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layer, err := opt.ContentStore.ReaderAt(ctx, desc)
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if err != nil {
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return fmt.Errorf("getting reader for digest %s failed: %v", desc.Digest.String(), err)
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}
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// Unpack the tarfile to the rootfs path.
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// FROM: https://godoc.org/github.com/moby/moby/pkg/archive#TarOptions
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if err := archive.Untar(content.NewReader(layer), dest, &archive.TarOptions{
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NoLchown: false,
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ExcludePatterns: []string{"dev/"}, // prevent 'operation not permitted'
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}); err != nil {
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return fmt.Errorf("extracting tar for %s to directory %s failed: %v", desc.Digest.String(), dest, err)
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}
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}
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return nil
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}
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