Add an option to specify a Create date for images

Add CommitOption option that to allow a caller to specify a creation
timestamp to use in images.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

Closes: #141
Approved by: rhatdan

cmd/buildah/commit.go

@@ -3,6 +3,7 @@ package main
 import (
 	"os"
 	"strings"
+	"time"
 
 	"github.com/containers/image/storage"
 	"github.com/containers/image/transports/alltransports"
@@ -15,7 +16,7 @@ import (
 var (
 	commitFlags = []cli.Flag{
 		cli.BoolFlag{
-			Name:  "disable-compression",
+			Name:  "disable-compression, D",
 			Usage: "don't compress layers",
 		},
 		cli.StringFlag{
@@ -26,6 +27,11 @@ var (
 			Name:  "format, f",
 			Usage: "`format` of the image manifest and metadata",
 		},
+		cli.StringFlag{
+			Name:   "reference-time",
+			Usage:  "set the timestamp on the image to match the named `file`",
+			Hidden: true,
+		},
 		cli.BoolFlag{
 			Name:  "quiet, q",
 			Usage: "don't output progress information when writing images",
@@ -73,6 +79,15 @@ func commitCmd(c *cli.Context) error {
 	if c.IsSet("format") {
 		format = c.String("format")
 	}
+	timestamp := time.Now().UTC()
+	if c.IsSet("reference-time") {
+		referenceFile := c.String("reference-time")
+		finfo, err := os.Stat(referenceFile)
+		if err != nil {
+			return errors.Wrapf(err, "error reading timestamp of file %q", referenceFile)
+		}
+		timestamp = finfo.ModTime().UTC()
+	}
 	if strings.HasPrefix(strings.ToLower(format), "oci") {
 		format = buildah.OCIv1ImageManifest
 	} else if strings.HasPrefix(strings.ToLower(format), "docker") {
@@ -103,6 +118,7 @@ func commitCmd(c *cli.Context) error {
 		PreferredManifestType: format,
 		Compression:           compress,
 		SignaturePolicyPath:   signaturePolicy,
+		HistoryTimestamp:      &timestamp,
 	}
 	if !quiet {
 		options.ReportWriter = os.Stderr

commit.go

@@ -3,6 +3,7 @@ package buildah
 import (
 	"bytes"
 	"io"
+	"time"
 
 	"github.com/Sirupsen/logrus"
 	cp "github.com/containers/image/copy"
@@ -50,6 +51,9 @@ type CommitOptions struct {
 	// ReportWriter is an io.Writer which will be used to log the writing
 	// of the new image.
 	ReportWriter io.Writer
+	// HistoryTimestamp is the timestamp used when creating new items in the
+	// image's history.  If unset, the current time will be used.
+	HistoryTimestamp *time.Time
 }
 
 // shallowCopy copies the most recent layer, the configuration, and the manifest from one image to another.
@@ -220,7 +224,7 @@ func (b *Builder) Commit(dest types.ImageReference, options CommitOptions) error
 	// Check if we're keeping everything in local storage.  If so, we can take certain shortcuts.
 	_, destIsStorage := dest.Transport().(storage.StoreTransport)
 	exporting := !destIsStorage
-	src, err := b.makeContainerImageRef(options.PreferredManifestType, exporting, options.Compression)
+	src, err := b.makeContainerImageRef(options.PreferredManifestType, exporting, options.Compression, options.HistoryTimestamp)
 	if err != nil {
 		return errors.Wrapf(err, "error recomputing layer digests and building metadata")
 	}

config.go

@@ -227,9 +227,16 @@ func (b *Builder) fixupConfig() {
 			b.Docker.Parent = docker.ID(digest.NewDigestFromHex(digest.Canonical.String(), b.FromImageID))
 		}
 	}
+	now := time.Now().UTC()
+	if b.Docker.Created.IsZero() {
+		b.Docker.Created = now
+	}
 	if b.FromImage != "" {
 		b.Docker.Config.Image = b.FromImage
 	}
+	if b.OCIv1.Created.IsZero() {
+		b.OCIv1.Created = now
+	}
 	if b.OS() == "" {
 		b.SetOS(runtime.GOOS)
 	}

contrib/completions/bash/buildah

@@ -295,6 +295,7 @@ return 1
           --signature-policy
           --format
           -f
+	  --reference-time
   "
 
      local all_options="$options_with_args $boolean_options"

docs/buildah-commit.md

@@ -33,6 +33,11 @@ Control the format for the image manifest and configuration data.  Recognized
 formats include *oci* (OCI image-spec v1.0, the default) and *docker* (version
 2, using schema format 2 for the manifest).
 
+**--reference-time**
+
+Sets the creation date in the image to match the last-modified time of the
+specified file.  This option is mainly present for use in buildah's self-tests.
+
 ## EXAMPLE
 
 buildah commit containerID

image.go

@@ -460,7 +460,7 @@ func (i *containerImageSource) GetBlob(blob types.BlobInfo) (reader io.ReadClose
 	return ioutils.NewReadCloserWrapper(layerFile, closer), size, nil
 }
 
-func (b *Builder) makeImageRef(manifestType string, exporting, addHistory bool, compress archive.Compression, names []string, layerID string) (types.ImageReference, error) {
+func (b *Builder) makeImageRef(manifestType string, exporting, addHistory bool, compress archive.Compression, names []string, layerID string, historyTimestamp *time.Time) (types.ImageReference, error) {
 	var name reference.Named
 	if len(names) > 0 {
 		if parsed, err := reference.ParseNamed(names[0]); err == nil {
@@ -478,6 +478,10 @@ func (b *Builder) makeImageRef(manifestType string, exporting, addHistory bool,
 	if err != nil {
 		return nil, errors.Wrapf(err, "error encoding docker-format image configuration")
 	}
+	created := time.Now().UTC()
+	if historyTimestamp != nil {
+		created = historyTimestamp.UTC()
+	}
 	ref := &containerImageRef{
 		store:                 b.store,
 		compression:           compress,
@@ -487,7 +491,7 @@ func (b *Builder) makeImageRef(manifestType string, exporting, addHistory bool,
 		addHistory:            addHistory,
 		oconfig:               oconfig,
 		dconfig:               dconfig,
-		created:               time.Now().UTC(),
+		created:               created,
 		createdBy:             b.CreatedBy(),
 		annotations:           b.Annotations(),
 		preferredManifestType: manifestType,
@@ -496,7 +500,7 @@ func (b *Builder) makeImageRef(manifestType string, exporting, addHistory bool,
 	return ref, nil
 }
 
-func (b *Builder) makeContainerImageRef(manifestType string, exporting bool, compress archive.Compression) (types.ImageReference, error) {
+func (b *Builder) makeContainerImageRef(manifestType string, exporting bool, compress archive.Compression, historyTimestamp *time.Time) (types.ImageReference, error) {
 	if manifestType == "" {
 		manifestType = OCIv1ImageManifest
 	}
@@ -504,9 +508,9 @@ func (b *Builder) makeContainerImageRef(manifestType string, exporting bool, com
 	if err != nil {
 		return nil, errors.Wrapf(err, "error locating container %q", b.ContainerID)
 	}
-	return b.makeImageRef(manifestType, exporting, true, compress, container.Names, container.LayerID)
+	return b.makeImageRef(manifestType, exporting, true, compress, container.Names, container.LayerID, historyTimestamp)
 }
 
-func (b *Builder) makeImageImageRef(compress archive.Compression, names []string, layerID string) (types.ImageReference, error) {
-	return b.makeImageRef(manifest.GuessMIMEType(b.Manifest), true, false, compress, names, layerID)
+func (b *Builder) makeImageImageRef(compress archive.Compression, names []string, layerID string, historyTimestamp *time.Time) (types.ImageReference, error) {
+	return b.makeImageRef(manifest.GuessMIMEType(b.Manifest), true, false, compress, names, layerID, historyTimestamp)
 }