build: fix iidfile content

build/build.go

@@ -762,7 +762,7 @@ func Build(ctx context.Context, drivers []DriverInfo, opt map[string]Options, do
 				resp[k] = res[0]
 				respMu.Unlock()
 				if len(res) == 1 {
-					digest := res[0].ExporterResponse["containerimage.digest"]
+					digest := res[0].ExporterResponse[exptypes.ExporterImageDigestKey]
 					if opt.ImageIDFile != "" {
 						return ioutil.WriteFile(opt.ImageIDFile, []byte(digest), 0644)
 					}
@@ -774,7 +774,7 @@ func Build(ctx context.Context, drivers []DriverInfo, opt map[string]Options, do
 						descs := make([]specs.Descriptor, 0, len(res))
 
 						for _, r := range res {
-							s, ok := r.ExporterResponse["containerimage.digest"]
+							s, ok := r.ExporterResponse[exptypes.ExporterImageDigestKey]
 							if ok {
 								descs = append(descs, specs.Descriptor{
 									Digest:    digest.Digest(s),
@@ -833,7 +833,7 @@ func Build(ctx context.Context, drivers []DriverInfo, opt map[string]Options, do
 							respMu.Lock()
 							resp[k] = &client.SolveResponse{
 								ExporterResponse: map[string]string{
-									"containerimage.digest": desc.Digest.String(),
+									exptypes.ExporterImageDigestKey: desc.Digest.String(),
 								},
 							}
 							respMu.Unlock()
@@ -918,29 +918,46 @@ func Build(ctx context.Context, drivers []DriverInfo, opt map[string]Options, do
 						if err != nil {
 							return err
 						}
-						res[i] = rr
 
 						d := drivers[dp.driverIndex].Driver
-						if d.IsMobyDriver() {
-							for _, e := range so.Exports {
+
+						for _, e := range so.Exports {
+							if d.IsMobyDriver() {
 								if e.Type == "moby" && e.Attrs["push"] != "" {
 									if ok, _ := strconv.ParseBool(e.Attrs["push"]); ok {
 										pushNames = e.Attrs["name"]
 										if pushNames == "" {
 											return errors.Errorf("tag is needed when pushing to registry")
 										}
 										pw := progress.ResetTime(pw)
-										for _, name := range strings.Split(pushNames, ",") {
+										pushList := strings.Split(pushNames, ",")
+										for _, name := range pushList {
 											if err := progress.Wrap(fmt.Sprintf("pushing %s with docker", name), pw.Write, func(l progress.SubLogger) error {
 												return pushWithMoby(ctx, d, name, l)
 											}); err != nil {
 												return err
 											}
 										}
+										remoteDigest, err := remoteDigestWithMoby(ctx, d, pushList[0])
+										if err == nil && remoteDigest != "" {
+											rr.ExporterResponse[exptypes.ExporterImageDigestKey] = remoteDigest
+										} else if err != nil {
+											return err
+										}
 									}
 								}
+							} else if names, ok := e.Attrs["name"]; ok && e.Type == "docker" {
+								nameList := strings.Split(names, ",")
+								imageID, err := dockerImageID(ctx, d, nameList[0])
+								if err == nil && imageID != "" {
+									rr.ExporterResponse[exptypes.ExporterImageDigestKey] = imageID
+								} else if err != nil {
+									return err
+								}
 							}
 						}
+
+						res[i] = rr
 						return nil
 					})
 
@@ -1038,9 +1055,45 @@ func pushWithMoby(ctx context.Context, d driver.Driver, name string, l progress.
 			parsedError = jm.Error
 		}
 	}
+
 	return nil
 }
 
+func remoteDigestWithMoby(ctx context.Context, d driver.Driver, name string) (string, error) {
+	api := d.Config().DockerAPI
+	if api == nil {
+		return "", errors.Errorf("invalid empty Docker API reference") // should never happen
+	}
+	creds, err := imagetools.RegistryAuthForRef(name, d.Config().Auth)
+	if err != nil {
+		return "", err
+	}
+	image, _, err := api.ImageInspectWithRaw(ctx, name)
+	if err != nil {
+		return "", err
+	}
+	if len(image.RepoDigests) == 0 {
+		return "", nil
+	}
+	remoteImage, err := api.DistributionInspect(ctx, name, creds)
+	if err != nil {
+		return "", err
+	}
+	return remoteImage.Descriptor.Digest.String(), nil
+}
+
+func dockerImageID(ctx context.Context, d driver.Driver, name string) (string, error) {
+	api := d.Config().DockerAPI
+	if api == nil {
+		return "", errors.Errorf("invalid empty Docker API reference") // should never happen
+	}
+	image, _, err := api.ImageInspectWithRaw(ctx, name)
+	if err != nil {
+		return "", err
+	}
+	return image.ID, nil
+}
+
 func createTempDockerfile(r io.Reader) (string, error) {
 	dir, err := ioutil.TempDir("", "dockerfile")
 	if err != nil {

commands/build.go

@@ -357,7 +357,7 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 	flags.StringVarP(&options.dockerfileName, "file", "f", "", `Name of the Dockerfile (default: "PATH/Dockerfile")`)
 	flags.SetAnnotation("file", annotation.ExternalURL, []string{"https://docs.docker.com/engine/reference/commandline/build/#specify-a-dockerfile--f"})
 
-	flags.StringVar(&options.imageIDFile, "iidfile", "", "Write the image ID to the file")
+	flags.StringVar(&options.imageIDFile, "iidfile", "", "Write the image ID or digest to the file")
 
 	flags.StringArrayVar(&options.labels, "label", []string{}, "Set metadata for an image")
 

docs/reference/buildx_build.md

@@ -24,7 +24,7 @@ Start a build
 | [`--cache-to`](#cache-to) | `stringArray` |  | Cache export destinations (e.g., `user/app:cache`, `type=local,dest=path/to/dir`) |
 | [`--cgroup-parent`](https://docs.docker.com/engine/reference/commandline/build/#use-a-custom-parent-cgroup---cgroup-parent) | `string` |  | Optional parent cgroup for the container |
 | [`-f`](https://docs.docker.com/engine/reference/commandline/build/#specify-a-dockerfile--f), [`--file`](https://docs.docker.com/engine/reference/commandline/build/#specify-a-dockerfile--f) | `string` |  | Name of the Dockerfile (default: `PATH/Dockerfile`) |
-| `--iidfile` | `string` |  | Write the image ID to the file |
+| [`--iidfile`](#iidfile) | `string` |  | Write the image ID or digest to the file |
 | `--label` | `stringArray` |  | Set metadata for an image |
 | [`--load`](#load) |  |  | Shorthand for `--output=type=docker` |
 | [`--metadata-file`](#metadata-file) | `string` |  | Write build result metadata to the file |
@@ -210,6 +210,16 @@ $ docker buildx build --cache-to=type=gha .
 
 More info about cache exporters and available attributes: https://github.com/moby/buildkit#export-cache
 
+### <a name="iidfile"></a> Write the image ID or digest to the file (--iidfile)
+
+Output the image ID or digest depending on the driver and output being used to
+the specified file:
+
+* `docker` driver : writes the image ID.
+* `docker` driver with `--push`: writes the image digest.
+* `docker-container` driver with `--load`: writes the image ID.
+* `docker-container` driver with `--push`: writes the image digest.
+
 ### <a name="load"></a> Load the single-platform build result to `docker images` (--load)
 
 Shorthand for [`--output=type=docker`](#docker). Will automatically load the