Add --digestfile option to push

Add the digestfile option to the push command so the digest can
be stored away in a file when requested by the user.  Also have added
a debug statement to show the completion of the push.

Emulates Buildah's https://github.com/containers/buildah/pull/1799/files

Signed-off-by: TomSweeneyRedHat <tsweeney@redhat.com>

1 files changed, 18 insertions, 5 deletions

diff --git a/libpod/image/image.go b/libpod/image/image.go
index cb7c390c6..1ff271a4d 100644
--- a/libpod/image/image.go
+++ b/libpod/image/image.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -555,7 +556,7 @@ func (i *Image) UntagImage(tag string) error {
 
 // PushImageToHeuristicDestination pushes the given image to "destination", which is heuristically parsed.
 // Use PushImageToReference if the destination is known precisely.
-func (i *Image) PushImageToHeuristicDestination(ctx context.Context, destination, manifestMIMEType, authFile, signaturePolicyPath string, writer io.Writer, forceCompress bool, signingOptions SigningOptions, dockerRegistryOptions *DockerRegistryOptions, additionalDockerArchiveTags []reference.NamedTagged) error {
+func (i *Image) PushImageToHeuristicDestination(ctx context.Context, destination, manifestMIMEType, authFile, digestFile, signaturePolicyPath string, writer io.Writer, forceCompress bool, signingOptions SigningOptions, dockerRegistryOptions *DockerRegistryOptions, additionalDockerArchiveTags []reference.NamedTagged) error {
 	if destination == "" {
 		return errors.Wrapf(syscall.EINVAL, "destination image name must be specified")
 	}
@@ -573,11 +574,11 @@ func (i *Image) PushImageToHeuristicDestination(ctx context.Context, destination
 			return err
 		}
 	}
-	return i.PushImageToReference(ctx, dest, manifestMIMEType, authFile, signaturePolicyPath, writer, forceCompress, signingOptions, dockerRegistryOptions, additionalDockerArchiveTags)
+	return i.PushImageToReference(ctx, dest, manifestMIMEType, authFile, digestFile, signaturePolicyPath, writer, forceCompress, signingOptions, dockerRegistryOptions, additionalDockerArchiveTags)
 }
 
 // PushImageToReference pushes the given image to a location described by the given path
-func (i *Image) PushImageToReference(ctx context.Context, dest types.ImageReference, manifestMIMEType, authFile, signaturePolicyPath string, writer io.Writer, forceCompress bool, signingOptions SigningOptions, dockerRegistryOptions *DockerRegistryOptions, additionalDockerArchiveTags []reference.NamedTagged) error {
+func (i *Image) PushImageToReference(ctx context.Context, dest types.ImageReference, manifestMIMEType, authFile, digestFile, signaturePolicyPath string, writer io.Writer, forceCompress bool, signingOptions SigningOptions, dockerRegistryOptions *DockerRegistryOptions, additionalDockerArchiveTags []reference.NamedTagged) error {
 	sc := GetSystemContext(signaturePolicyPath, authFile, forceCompress)
 	sc.BlobInfoCacheDir = filepath.Join(i.imageruntime.store.GraphRoot(), "cache")
 
@@ -599,10 +600,22 @@ func (i *Image) PushImageToReference(ctx context.Context, dest types.ImageRefere
 	copyOptions := getCopyOptions(sc, writer, nil, dockerRegistryOptions, signingOptions, manifestMIMEType, additionalDockerArchiveTags)
 	copyOptions.DestinationCtx.SystemRegistriesConfPath = registries.SystemRegistriesConfPath() // FIXME: Set this more globally.  Probably no reason not to have it in every types.SystemContext, and to compute the value just once in one place.
 	// Copy the image to the remote destination
-	_, err = cp.Image(ctx, policyContext, dest, src, copyOptions)
+	manifestBytes, err := cp.Image(ctx, policyContext, dest, src, copyOptions)
 	if err != nil {
 		return errors.Wrapf(err, "Error copying image to the remote destination")
 	}
+	digest, err := manifest.Digest(manifestBytes)
+	if err != nil {
+		return errors.Wrapf(err, "error computing digest of manifest of new image %q", transports.ImageName(dest))
+	}
+
+	logrus.Debugf("Successfully pushed %s with digest %s", transports.ImageName(dest), digest.String())
+
+	if digestFile != "" {
+		if err = ioutil.WriteFile(digestFile, []byte(digest.String()), 0644); err != nil {
+			return errors.Wrapf(err, "failed to write digest to file %q", digestFile)
+		}
+	}
 	i.newImageEvent(events.Push)
 	return nil
 }
@@ -1358,7 +1371,7 @@ func (i *Image) Save(ctx context.Context, source, format, output string, moreTag
 			return err
 		}
 	}
-	if err := i.PushImageToReference(ctx, destRef, manifestType, "", "", writer, compress, SigningOptions{}, &DockerRegistryOptions{}, additionaltags); err != nil {
+	if err := i.PushImageToReference(ctx, destRef, manifestType, "", "", "", writer, compress, SigningOptions{}, &DockerRegistryOptions{}, additionaltags); err != nil {
 		return errors.Wrapf(err, "unable to save %q", source)
 	}
 	i.newImageEvent(events.Save)