Add metadata-file flag

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

bake/bake.go

@@ -317,6 +317,8 @@ func (c Config) newOverrides(v []string) (map[string]*Target, error) {
 					return nil, errors.Errorf("invalid value %s for boolean key pull", parts[1])
 				}
 				t.Pull = &pull
+			case "metadata-file":
+				continue
 			default:
 				return nil, errors.Errorf("unknown key: %s", keys[1])
 			}
@@ -434,6 +436,7 @@ type Target struct {
 	Outputs          []string          `json:"output,omitempty" hcl:"output,optional"`
 	Pull             *bool             `json:"pull,omitempty" hcl:"pull,optional"`
 	NoCache          *bool             `json:"no-cache,omitempty" hcl:"no-cache,optional"`
+	MetadataFile     *string           `json:"-" hcl:"-"`
 
 	// IMPORTANT: if you add more fields here, do not forget to update newOverrides and README.
 }
@@ -448,13 +451,16 @@ func (t *Target) normalize() {
 	t.Outputs = removeDupes(t.Outputs)
 }
 
-func TargetsToBuildOpt(m map[string]*Target, inp *Input) (map[string]build.Options, error) {
+func TargetsToBuildOpt(m map[string]*Target, inp *Input, metadataFile string) (map[string]build.Options, error) {
 	m2 := make(map[string]build.Options, len(m))
 	for k, v := range m {
-		bo, err := toBuildOpt(v, inp)
+		bo, err := toBuildOpt(k, v, inp)
 		if err != nil {
 			return nil, err
 		}
+		if len(metadataFile) > 0 {
+			bo.MetadataFile = metadataFile
+		}
 		m2[k] = *bo
 	}
 	return m2, nil
@@ -472,7 +478,7 @@ func updateContext(t *build.Inputs, inp *Input) {
 	t.ContextState = &st
 }
 
-func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
+func toBuildOpt(n string, t *Target, inp *Input) (*build.Options, error) {
 	if v := t.Context; v != nil && *v == "-" {
 		return nil, errors.Errorf("context from stdin not allowed in bake")
 	}
@@ -502,6 +508,10 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	if t.Pull != nil {
 		pull = *t.Pull
 	}
+	metadataFile := ""
+	if t.MetadataFile != nil {
+		metadataFile = *t.MetadataFile
+	}
 
 	bi := build.Inputs{
 		ContextPath:    contextPath,
@@ -513,12 +523,14 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	updateContext(&bi, inp)
 
 	bo := &build.Options{
-		Inputs:    bi,
-		Tags:      t.Tags,
-		BuildArgs: t.Args,
-		Labels:    t.Labels,
-		NoCache:   noCache,
-		Pull:      pull,
+		Inputs:         bi,
+		Tags:           t.Tags,
+		BuildArgs:      t.Args,
+		Labels:         t.Labels,
+		NoCache:        noCache,
+		Pull:           pull,
+		MetadataFile:   metadataFile,
+		BakeDefinition: t,
 	}
 
 	platforms, err := platformutil.Parse(t.Platforms)

build/build.go

@@ -46,14 +46,15 @@ var (
 )
 
 type Options struct {
-	Inputs      Inputs
-	Tags        []string
-	Labels      map[string]string
-	BuildArgs   map[string]string
-	Pull        bool
-	ImageIDFile string
-	ExtraHosts  []string
-	NetworkMode string
+	Inputs       Inputs
+	Tags         []string
+	Labels       map[string]string
+	BuildArgs    map[string]string
+	Pull         bool
+	ImageIDFile  string
+	MetadataFile string
+	ExtraHosts   []string
+	NetworkMode  string
 
 	NoCache   bool
 	Target    string
@@ -65,7 +66,8 @@ type Options struct {
 	CacheTo   []client.CacheOptionsEntry
 
 	Allow []entitlements.Entitlement
-	// DockerTarget
+
+	BakeDefinition interface{}
 }
 
 type Inputs struct {
@@ -342,6 +344,12 @@ func toSolveOpt(ctx context.Context, d driver.Driver, multiDriver bool, opt Opti
 			return nil, nil, errors.Wrap(err, "removing image ID file")
 		}
 	}
+	if opt.MetadataFile != "" {
+		// Avoid leaving a stale file if we eventually fail
+		if err := os.Remove(opt.MetadataFile); err != nil && !os.IsNotExist(err) {
+			return nil, nil, errors.Wrap(err, "removing metadata file")
+		}
+	}
 
 	// inline cache from build arg
 	if v, ok := opt.BuildArgs["BUILDKIT_INLINE_CACHE"]; ok {
@@ -656,6 +664,29 @@ func Build(ctx context.Context, drivers []DriverInfo, opt map[string]Options, do
 				respMu.Lock()
 				resp[k] = res[0]
 				respMu.Unlock()
+
+				if opt.MetadataFile != "" {
+					metadata := make([]map[string]string, 0, len(res))
+					for _, r := range res {
+						if _, ok := r.ExporterResponse["containerimage.digest"]; ok {
+							metadata = append(metadata, r.ExporterResponse)
+						}
+					}
+					mdatab, err := json.MarshalIndent(map[string]interface{}{k: struct {
+						Definition interface{}         `json:"definition,omitempty"`
+						Metadata   []map[string]string `json:"metadata,omitempty"`
+					}{
+						Definition: opt.BakeDefinition,
+						Metadata:   metadata,
+					}}, "", "  ")
+					if err != nil {
+						return err
+					}
+					if err := ioutil.WriteFile(opt.MetadataFile, mdatab, 0644); err != nil {
+						return err
+					}
+				}
+
 				if len(res) == 1 {
 					if opt.ImageIDFile != "" {
 						return ioutil.WriteFile(opt.ImageIDFile, []byte(res[0].ExporterResponse["containerimage.digest"]), 0644)

commands/bake.go

@@ -53,6 +53,9 @@ func runBake(dockerCli command.Cli, targets []string, in bakeOptions) (err error
 	if in.pull != nil {
 		overrides = append(overrides, fmt.Sprintf("*.pull=%t", *in.pull))
 	}
+	if len(in.metadataFile) > 0 {
+		overrides = append(overrides, fmt.Sprintf("*.metadata-file=%s", in.metadataFile))
+	}
 	contextPathHash, _ := os.Getwd()
 
 	ctx2, cancel := context.WithCancel(context.TODO())
@@ -103,7 +106,7 @@ func runBake(dockerCli command.Cli, targets []string, in bakeOptions) (err error
 		return nil
 	}
 
-	bo, err := bake.TargetsToBuildOpt(m, inp)
+	bo, err := bake.TargetsToBuildOpt(m, inp, in.metadataFile)
 	if err != nil {
 		return err
 	}

commands/build.go

@@ -64,10 +64,11 @@ type buildOptions struct {
 }
 
 type commonOptions struct {
-	builder  string
-	noCache  *bool
-	progress string
-	pull     *bool
+	builder      string
+	noCache      *bool
+	progress     string
+	pull         *bool
+	metadataFile string
 	// golangci-lint#826
 	// nolint:structcheck
 	exportPush bool
@@ -100,15 +101,16 @@ func runBuild(dockerCli command.Cli, in buildOptions) error {
 			DockerfilePath: in.dockerfileName,
 			InStream:       os.Stdin,
 		},
-		Tags:        in.tags,
-		Labels:      listToMap(in.labels, false),
-		BuildArgs:   listToMap(in.buildArgs, true),
-		Pull:        pull,
-		NoCache:     noCache,
-		Target:      in.target,
-		ImageIDFile: in.imageIDFile,
-		ExtraHosts:  in.extraHosts,
-		NetworkMode: in.networkMode,
+		Tags:         in.tags,
+		Labels:       listToMap(in.labels, false),
+		BuildArgs:    listToMap(in.buildArgs, true),
+		Pull:         pull,
+		NoCache:      noCache,
+		Target:       in.target,
+		ImageIDFile:  in.imageIDFile,
+		MetadataFile: in.metadataFile,
+		ExtraHosts:   in.extraHosts,
+		NetworkMode:  in.networkMode,
 	}
 
 	platforms, err := platformutil.Parse(in.platforms)
@@ -333,6 +335,7 @@ func commonBuildFlags(options *commonOptions, flags *pflag.FlagSet) {
 	flags.StringVar(&options.progress, "progress", defaultProgress, "Set type of progress output (auto, plain, tty). Use plain to show container output")
 
 	options.pull = flags.Bool("pull", false, "Always attempt to pull a newer version of the image")
+	flags.StringVar(&options.metadataFile, "metadata-file", "", "Write build metadata to a file as JSON")
 }
 
 func listToMap(values []string, defaultEnv bool) map[string]string {

docs/reference/buildx_bake.md

@@ -18,6 +18,7 @@ Build from a file
 | `--builder string` | Override the configured builder instance |
 | [`-f`](#file), [`--file stringArray`](#file) | Build definition file |
 | `--load` | Shorthand for --set=*.output=type=docker |
+| `--metadata-file string` | Write build metadata to a file as JSON |
 | [`--no-cache`](#no-cache) | Do not use cache when building the image |
 | [`--print`](#print) | Print the options without building |
 | [`--progress string`](#progress) | Set type of progress output (auto, plain, tty). Use plain to show container output |

docs/reference/buildx_build.md

@@ -25,6 +25,7 @@ Start a build
 | `--iidfile string` | Write the image ID to the file |
 | `--label stringArray` | Set metadata for an image |
 | [`--load`](#load) | Shorthand for --output=type=docker |
+| `--metadata-file string` | Write build metadata to a file as JSON |
 | `--network string` | Set the networking mode for the RUN instructions during build |
 | `--no-cache` | Do not use cache when building the image |
 | [`-o`](#output), [`--output stringArray`](#output) | Output destination (format: type=local,dest=path) |