458 lines
12 KiB
Go
458 lines
12 KiB
Go
package containerimage
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"runtime"
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"time"
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"github.com/containerd/containerd/content"
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"github.com/containerd/containerd/diff"
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"github.com/containerd/containerd/images"
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"github.com/moby/buildkit/cache"
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"github.com/moby/buildkit/cache/blobs"
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"github.com/moby/buildkit/exporter"
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"github.com/moby/buildkit/exporter/containerimage/exptypes"
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"github.com/moby/buildkit/snapshot"
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"github.com/moby/buildkit/util/progress"
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"github.com/moby/buildkit/util/system"
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digest "github.com/opencontainers/go-digest"
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specs "github.com/opencontainers/image-spec/specs-go"
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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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"github.com/sirupsen/logrus"
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"golang.org/x/sync/errgroup"
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)
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const (
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emptyGZLayer = digest.Digest("sha256:4f4fb700ef54461cfa02571ae0db9a0dc1e0cdb5577484a6d75e68dc38e8acc1")
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)
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type WriterOpt struct {
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Snapshotter snapshot.Snapshotter
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ContentStore content.Store
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Differ diff.Comparer
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}
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func NewImageWriter(opt WriterOpt) (*ImageWriter, error) {
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return &ImageWriter{opt: opt}, nil
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}
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type ImageWriter struct {
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opt WriterOpt
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}
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func (ic *ImageWriter) Commit(ctx context.Context, inp exporter.Source, oci bool) (*ocispec.Descriptor, error) {
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platformsBytes, ok := inp.Metadata[exptypes.ExporterPlatformsKey]
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if len(inp.Refs) > 0 && !ok {
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return nil, errors.Errorf("unable to export multiple refs, missing platforms mapping")
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}
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if len(inp.Refs) == 0 {
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layers, err := ic.exportLayers(ctx, inp.Ref)
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if err != nil {
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return nil, err
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}
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return ic.commitDistributionManifest(ctx, inp.Ref, inp.Metadata[exptypes.ExporterImageConfigKey], layers[0], oci)
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}
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var p exptypes.Platforms
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if err := json.Unmarshal(platformsBytes, &p); err != nil {
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return nil, errors.Wrapf(err, "failed to parse platforms passed to exporter")
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}
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if len(p.Platforms) != len(inp.Refs) {
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return nil, errors.Errorf("number of platforms does not match references %d %d", len(p.Platforms), len(inp.Refs))
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}
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refs := make([]cache.ImmutableRef, 0, len(inp.Refs))
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layersMap := make(map[string]int, len(inp.Refs))
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for id, r := range inp.Refs {
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layersMap[id] = len(refs)
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refs = append(refs, r)
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}
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layers, err := ic.exportLayers(ctx, refs...)
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if err != nil {
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return nil, err
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}
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idx := struct {
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// MediaType is reserved in the OCI spec but
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// excluded from go types.
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MediaType string `json:"mediaType,omitempty"`
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ocispec.Index
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}{
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MediaType: ocispec.MediaTypeImageIndex,
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Index: ocispec.Index{
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Versioned: specs.Versioned{
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SchemaVersion: 2,
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},
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},
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}
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if !oci {
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idx.MediaType = images.MediaTypeDockerSchema2ManifestList
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}
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labels := map[string]string{}
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for i, p := range p.Platforms {
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r, ok := inp.Refs[p.ID]
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if !ok {
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return nil, errors.Errorf("failed to find ref for ID %s", p.ID)
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}
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config := inp.Metadata[fmt.Sprintf("%s/%s", exptypes.ExporterImageConfigKey, p.ID)]
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desc, err := ic.commitDistributionManifest(ctx, r, config, layers[layersMap[p.ID]], oci)
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if err != nil {
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return nil, err
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}
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dp := p.Platform
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desc.Platform = &dp
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idx.Manifests = append(idx.Manifests, *desc)
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labels[fmt.Sprintf("containerd.io/gc.ref.content.%d", i)] = desc.Digest.String()
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}
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idxBytes, err := json.MarshalIndent(idx, "", " ")
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if err != nil {
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return nil, errors.Wrap(err, "failed to marshal index")
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}
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idxDigest := digest.FromBytes(idxBytes)
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idxDesc := ocispec.Descriptor{
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Digest: idxDigest,
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Size: int64(len(idxBytes)),
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MediaType: idx.MediaType,
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}
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idxDone := oneOffProgress(ctx, "exporting manifest list "+idxDigest.String())
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if err := content.WriteBlob(ctx, ic.opt.ContentStore, idxDigest.String(), bytes.NewReader(idxBytes), idxDesc, content.WithLabels(labels)); err != nil {
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return nil, idxDone(errors.Wrapf(err, "error writing manifest list blob %s", idxDigest))
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}
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idxDone(nil)
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for _, desc := range idx.Manifests {
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// delete manifest root. manifest will remain linked to the index
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if err := ic.opt.ContentStore.Delete(context.TODO(), desc.Digest); err != nil {
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return nil, errors.Wrap(err, "error removing manifest root")
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}
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}
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return &idxDesc, nil
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}
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func (ic *ImageWriter) exportLayers(ctx context.Context, refs ...cache.ImmutableRef) ([][]blobs.DiffPair, error) {
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eg, ctx := errgroup.WithContext(ctx)
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layersDone := oneOffProgress(ctx, "exporting layers")
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out := make([][]blobs.DiffPair, len(refs))
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for i, ref := range refs {
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func(i int, ref cache.ImmutableRef) {
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eg.Go(func() error {
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diffPairs, err := blobs.GetDiffPairs(ctx, ic.opt.ContentStore, ic.opt.Snapshotter, ic.opt.Differ, ref, true)
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if err != nil {
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return errors.Wrap(err, "failed calculating diff pairs for exported snapshot")
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}
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out[i] = diffPairs
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return nil
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})
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}(i, ref)
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}
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if err := layersDone(eg.Wait()); err != nil {
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return nil, err
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}
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return out, nil
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}
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func (ic *ImageWriter) commitDistributionManifest(ctx context.Context, ref cache.ImmutableRef, config []byte, layers []blobs.DiffPair, oci bool) (*ocispec.Descriptor, error) {
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if len(config) == 0 {
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var err error
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config, err = emptyImageConfig()
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if err != nil {
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return nil, err
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}
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}
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history, err := parseHistoryFromConfig(config)
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if err != nil {
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return nil, err
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}
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diffPairs, history := normalizeLayersAndHistory(layers, history, ref)
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config, err = patchImageConfig(config, diffPairs, history)
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if err != nil {
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return nil, err
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}
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var (
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configDigest = digest.FromBytes(config)
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manifestType = ocispec.MediaTypeImageManifest
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configType = ocispec.MediaTypeImageConfig
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layerType = ocispec.MediaTypeImageLayerGzip
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)
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// Use docker media types for older Docker versions and registries
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if !oci {
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manifestType = images.MediaTypeDockerSchema2Manifest
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configType = images.MediaTypeDockerSchema2Config
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layerType = images.MediaTypeDockerSchema2LayerGzip
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}
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mfst := struct {
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// MediaType is reserved in the OCI spec but
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// excluded from go types.
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MediaType string `json:"mediaType,omitempty"`
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ocispec.Manifest
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}{
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MediaType: manifestType,
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Manifest: ocispec.Manifest{
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Versioned: specs.Versioned{
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SchemaVersion: 2,
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},
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Config: ocispec.Descriptor{
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Digest: configDigest,
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Size: int64(len(config)),
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MediaType: configType,
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},
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},
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}
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labels := map[string]string{
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"containerd.io/gc.ref.content.0": configDigest.String(),
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}
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for i, dp := range diffPairs {
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info, err := ic.opt.ContentStore.Info(ctx, dp.Blobsum)
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if err != nil {
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return nil, errors.Wrapf(err, "could not find blob %s from contentstore", dp.Blobsum)
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}
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mfst.Layers = append(mfst.Layers, ocispec.Descriptor{
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Digest: dp.Blobsum,
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Size: info.Size,
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MediaType: layerType,
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})
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labels[fmt.Sprintf("containerd.io/gc.ref.content.%d", i+1)] = dp.Blobsum.String()
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}
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mfstJSON, err := json.MarshalIndent(mfst, "", " ")
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if err != nil {
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return nil, errors.Wrap(err, "failed to marshal manifest")
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}
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mfstDigest := digest.FromBytes(mfstJSON)
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mfstDesc := ocispec.Descriptor{
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Digest: mfstDigest,
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Size: int64(len(mfstJSON)),
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}
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mfstDone := oneOffProgress(ctx, "exporting manifest "+mfstDigest.String())
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if err := content.WriteBlob(ctx, ic.opt.ContentStore, mfstDigest.String(), bytes.NewReader(mfstJSON), mfstDesc, content.WithLabels(labels)); err != nil {
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return nil, mfstDone(errors.Wrapf(err, "error writing manifest blob %s", mfstDigest))
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}
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mfstDone(nil)
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configDesc := ocispec.Descriptor{
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Digest: configDigest,
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Size: int64(len(config)),
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MediaType: configType,
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}
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configDone := oneOffProgress(ctx, "exporting config "+configDigest.String())
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if err := content.WriteBlob(ctx, ic.opt.ContentStore, configDigest.String(), bytes.NewReader(config), configDesc); err != nil {
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return nil, configDone(errors.Wrap(err, "error writing config blob"))
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}
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configDone(nil)
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// delete config root. config will remain linked to the manifest
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if err := ic.opt.ContentStore.Delete(context.TODO(), configDigest); err != nil {
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return nil, errors.Wrap(err, "error removing config root")
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}
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return &ocispec.Descriptor{
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Digest: mfstDigest,
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Size: int64(len(mfstJSON)),
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MediaType: manifestType,
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}, nil
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}
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func (ic *ImageWriter) ContentStore() content.Store {
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return ic.opt.ContentStore
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}
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func emptyImageConfig() ([]byte, error) {
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img := ocispec.Image{
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Architecture: runtime.GOARCH,
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OS: runtime.GOOS,
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}
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img.RootFS.Type = "layers"
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img.Config.WorkingDir = "/"
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img.Config.Env = []string{"PATH=" + system.DefaultPathEnv}
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dt, err := json.Marshal(img)
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return dt, errors.Wrap(err, "failed to create empty image config")
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}
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func parseHistoryFromConfig(dt []byte) ([]ocispec.History, error) {
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var config struct {
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History []ocispec.History
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}
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if err := json.Unmarshal(dt, &config); err != nil {
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return nil, errors.Wrap(err, "failed to unmarshal history from config")
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}
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return config.History, nil
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}
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func patchImageConfig(dt []byte, dps []blobs.DiffPair, history []ocispec.History) ([]byte, error) {
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m := map[string]json.RawMessage{}
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if err := json.Unmarshal(dt, &m); err != nil {
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return nil, errors.Wrap(err, "failed to parse image config for patch")
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}
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var rootFS ocispec.RootFS
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rootFS.Type = "layers"
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for _, dp := range dps {
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rootFS.DiffIDs = append(rootFS.DiffIDs, dp.DiffID)
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}
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dt, err := json.Marshal(rootFS)
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if err != nil {
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return nil, errors.Wrap(err, "failed to marshal rootfs")
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}
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m["rootfs"] = dt
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dt, err = json.Marshal(history)
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if err != nil {
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return nil, errors.Wrap(err, "failed to marshal history")
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}
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m["history"] = dt
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if _, ok := m["created"]; !ok {
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var tm *time.Time
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for _, h := range history {
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if h.Created != nil {
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tm = h.Created
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}
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}
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dt, err = json.Marshal(&tm)
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if err != nil {
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return nil, errors.Wrap(err, "failed to marshal creation time")
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}
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m["created"] = dt
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}
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dt, err = json.Marshal(m)
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return dt, errors.Wrap(err, "failed to marshal config after patch")
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}
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func normalizeLayersAndHistory(diffs []blobs.DiffPair, history []ocispec.History, ref cache.ImmutableRef) ([]blobs.DiffPair, []ocispec.History) {
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refMeta := getRefMetadata(ref, len(diffs))
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var historyLayers int
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for _, h := range history {
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if !h.EmptyLayer {
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historyLayers += 1
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}
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}
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if historyLayers > len(diffs) {
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// this case shouldn't happen but if it does force set history layers empty
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// from the bottom
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logrus.Warn("invalid image config with unaccounted layers")
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historyCopy := make([]ocispec.History, 0, len(history))
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var l int
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for _, h := range history {
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if l >= len(diffs) {
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h.EmptyLayer = true
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}
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if !h.EmptyLayer {
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l++
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}
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historyCopy = append(historyCopy, h)
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}
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history = historyCopy
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}
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if len(diffs) > historyLayers {
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// some history items are missing. add them based on the ref metadata
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for _, md := range refMeta[historyLayers:] {
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history = append(history, ocispec.History{
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Created: &md.createdAt,
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CreatedBy: md.description,
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Comment: "buildkit.exporter.image.v0",
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})
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}
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}
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var layerIndex int
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for i, h := range history {
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if !h.EmptyLayer {
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if h.Created == nil {
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h.Created = &refMeta[layerIndex].createdAt
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}
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if diffs[layerIndex].Blobsum == emptyGZLayer {
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h.EmptyLayer = true
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diffs = append(diffs[:layerIndex], diffs[layerIndex+1:]...)
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} else {
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layerIndex++
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}
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}
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history[i] = h
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}
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return diffs, history
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}
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type refMetadata struct {
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description string
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createdAt time.Time
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}
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func getRefMetadata(ref cache.ImmutableRef, limit int) []refMetadata {
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if limit <= 0 {
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return nil
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}
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meta := refMetadata{
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description: "created by buildkit", // shouldn't be shown but don't fail build
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createdAt: time.Now(),
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}
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if ref == nil {
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return append(getRefMetadata(nil, limit-1), meta)
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}
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if descr := cache.GetDescription(ref.Metadata()); descr != "" {
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meta.description = descr
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}
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meta.createdAt = cache.GetCreatedAt(ref.Metadata())
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p := ref.Parent()
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if p != nil {
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defer p.Release(context.TODO())
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}
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return append(getRefMetadata(p, limit-1), meta)
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}
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func oneOffProgress(ctx context.Context, id string) func(err error) error {
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pw, _, _ := progress.FromContext(ctx)
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now := time.Now()
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st := progress.Status{
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Started: &now,
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}
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pw.Write(id, st)
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return func(err error) error {
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// TODO: set error on status
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now := time.Now()
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st.Completed = &now
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pw.Write(id, st)
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pw.Close()
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return err
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}
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}
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