d7af92e00c
This moves both the Mount type and mountinfo into a single mount package. This also opens up the root of the repo to hold the containerd client implementation. Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
package rootfs
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import (
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"context"
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"fmt"
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"github.com/containerd/containerd/log"
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"github.com/containerd/containerd/mount"
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"github.com/containerd/containerd/snapshot"
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"github.com/opencontainers/go-digest"
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"github.com/opencontainers/image-spec/identity"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/pkg/errors"
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)
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type Applier interface {
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Apply(context.Context, ocispec.Descriptor, []mount.Mount) (ocispec.Descriptor, error)
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}
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type Layer struct {
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Diff ocispec.Descriptor
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Blob ocispec.Descriptor
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}
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func ApplyLayers(ctx context.Context, layers []Layer, sn snapshot.Snapshotter, a Applier) (digest.Digest, error) {
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var chain []digest.Digest
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for _, layer := range layers {
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if err := applyLayer(ctx, layer, chain, sn, a); err != nil {
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// TODO: possibly wait and retry if extraction of same chain id was in progress
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return "", err
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}
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chain = append(chain, layer.Diff.Digest)
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}
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return identity.ChainID(chain), nil
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}
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func applyLayer(ctx context.Context, layer Layer, chain []digest.Digest, sn snapshot.Snapshotter, a Applier) error {
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var (
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parent = identity.ChainID(chain)
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chainID = identity.ChainID(append(chain, layer.Diff.Digest))
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diff ocispec.Descriptor
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)
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_, err := sn.Stat(ctx, chainID.String())
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if err == nil {
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log.G(ctx).Debugf("Extraction not needed, layer snapshot exists")
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return nil
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} else if !snapshot.IsNotExist(err) {
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return errors.Wrap(err, "failed to stat snapshot")
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}
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key := fmt.Sprintf("extract %s", chainID)
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// Prepare snapshot with from parent
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mounts, err := sn.Prepare(ctx, key, parent.String())
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if err != nil {
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//TODO: If is snapshot exists error, retry
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return errors.Wrap(err, "failed to prepare extraction layer")
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}
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defer func() {
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if err != nil {
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log.G(ctx).WithError(err).WithField("key", key).Infof("Apply failure, attempting cleanup")
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if rerr := sn.Remove(ctx, key); rerr != nil {
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log.G(ctx).WithError(rerr).Warnf("Extraction snapshot %q removal failed: %v", key)
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}
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}
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}()
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diff, err = a.Apply(ctx, layer.Blob, mounts)
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if err != nil {
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return errors.Wrapf(err, "failed to extract layer %s", layer.Diff.Digest)
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}
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if diff.Digest != layer.Diff.Digest {
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err = errors.Errorf("wrong diff id calculated on extraction %q", diff.Digest)
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return err
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}
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if err = sn.Commit(ctx, chainID.String(), key); err != nil {
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return errors.Wrapf(err, "failed to commit snapshot %s", parent)
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}
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return nil
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}
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