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archive: add WithSourceDateEpoch() for whiteouts

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This makes diff archives to be reproducible.

The value is expected to be passed from CLI applications via the $SOUCE_DATE_EPOCH env var.

See https://reproducible-builds.org/docs/source-date-epoch/
for the $SOURCE_DATE_EPOCH specification.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
This commit is contained in:
Akihiro Suda
2022-10-08 08:45:03 +09:00
parent 6fcfcf3a89
commit 70fbedc217
13 changed files with 390 additions and 104 deletions
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13
diff/diff.go
View File

@@ -19,6 +19,7 @@ package diff
import (
"context"
"io"
"time"
"github.com/containerd/containerd/mount"
"github.com/containerd/typeurl"
@@ -44,6 +45,9 @@ type Config struct {
// the MediaType of the target diff content to the compressor.
// When using this config, MediaType must be specified as well.
Compressor func(dest io.Writer, mediaType string) (io.WriteCloser, error)
// SourceDateEpoch specifies the SOURCE_DATE_EPOCH without touching the env vars.
SourceDateEpoch *time.Time
}
// Opt is used to configure a diff operation
@@ -120,3 +124,12 @@ func WithPayloads(payloads map[string]typeurl.Any) ApplyOpt {
return nil
}
}
// WithSourceDateEpoch specifies the timestamp used for whiteouts to provide control for reproducibility.
// See also https://reproducible-builds.org/docs/source-date-epoch/ .
func WithSourceDateEpoch(tm *time.Time) Opt {
return func(c *Config) error {
c.SourceDateEpoch = tm
return nil
}
}

9
diff/walking/differ.go
View File

@@ -65,6 +65,11 @@ func (s *walkingDiff) Compare(ctx context.Context, lower, upper []mount.Mount, o
}
}
var writeDiffOpts []archive.WriteDiffOpt
if config.SourceDateEpoch != nil {
writeDiffOpts = append(writeDiffOpts, archive.WithSourceDateEpoch(config.SourceDateEpoch))
}
var isCompressed bool
if config.Compressor != nil {
if config.MediaType == "" {
@@ -136,7 +141,7 @@ func (s *walkingDiff) Compare(ctx context.Context, lower, upper []mount.Mount, o
return fmt.Errorf("failed to get compressed stream: %w", errOpen)
}
}
errOpen = archive.WriteDiff(ctx, io.MultiWriter(compressed, dgstr.Hash()), lowerRoot, upperRoot)
errOpen = archive.WriteDiff(ctx, io.MultiWriter(compressed, dgstr.Hash()), lowerRoot, upperRoot, writeDiffOpts...)
compressed.Close()
if errOpen != nil {
return fmt.Errorf("failed to write compressed diff: %w", errOpen)
@@ -147,7 +152,7 @@ func (s *walkingDiff) Compare(ctx context.Context, lower, upper []mount.Mount, o
}
config.Labels[uncompressed] = dgstr.Digest().String()
} else {
if errOpen = archive.WriteDiff(ctx, cw, lowerRoot, upperRoot); errOpen != nil {
if errOpen = archive.WriteDiff(ctx, cw, lowerRoot, upperRoot, writeDiffOpts...); errOpen != nil {
return fmt.Errorf("failed to write diff: %w", errOpen)
}
}