build: create parent directories for tar output in lazy writer

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

build/opt.go

@@ -876,11 +876,7 @@ func CreateExports(entries []*buildflags.ExportEntry) ([]client.ExportEntry, []s
 				if err == nil && fi.IsDir() {
 					return nil, nil, errors.Errorf("destination file %s is a directory", entry.Destination)
 				}
-				f, err := os.Create(entry.Destination)
+				out.Output = wrapWriteCloserLazy(entry.Destination)
-				if err != nil {
-					return nil, nil, errors.Errorf("failed to open %s", err)
-				}
-				out.Output = wrapWriteCloser(f)
 				localPaths = append(localPaths, entry.Destination)
 			}
 		}
@@ -896,6 +892,38 @@ func wrapWriteCloser(wc io.WriteCloser) func(map[string]string) (io.WriteCloser,
 	}
 }
 
+type lazyFileWriter struct {
+	path string
+	file *os.File
+}
+
+func (w *lazyFileWriter) Write(p []byte) (int, error) {
+	if w.file == nil {
+		if err := os.MkdirAll(filepath.Dir(w.path), 0755); err != nil {
+			return 0, err
+		}
+		f, err := os.Create(w.path)
+		if err != nil {
+			return 0, err
+		}
+		w.file = f
+	}
+	return w.file.Write(p)
+}
+
+func (w *lazyFileWriter) Close() error {
+	if w.file != nil {
+		return w.file.Close()
+	}
+	return nil
+}
+
+func wrapWriteCloserLazy(path string) func(map[string]string) (io.WriteCloser, error) {
+	return func(map[string]string) (io.WriteCloser, error) {
+		return &lazyFileWriter{path: path}, nil
+	}
+}
+
 func CreateCaches(entries []*buildflags.CacheOptionsEntry) []client.CacheOptionsEntry {
 	var outs []client.CacheOptionsEntry
 	if len(entries) == 0 {

tests/bake.go

@@ -1359,17 +1359,19 @@ target "default" {
 
 	dirDest := t.TempDir()
 
+	envs := []string{"BUILDX_METADATA_PROVENANCE=" + metadataMode}
 	outFlag := "default.output=type=docker"
 	if sb.DockerAddress() == "" {
 		// there is no Docker atm to load the image
 		outFlag += ",dest=" + dirDest + "/image.tar"
+		envs = append(envs, "BUILDX_BAKE_ENTITLEMENTS_FS=0")
 	}
 
 	cmd := buildxCmd(
 		sb,
 		withDir(dir),
 		withArgs("bake", "--metadata-file", filepath.Join(dirDest, "md.json"), "--set", outFlag),
-		withEnv("BUILDX_METADATA_PROVENANCE="+metadataMode),
+		withEnv(envs...),
 	)
 	out, err := cmd.CombinedOutput()
 	require.NoError(t, err, string(out))

tests/build.go

@@ -417,10 +417,11 @@ func testBuildLocalExport(t *testing.T, sb integration.Sandbox) {
 
 func testBuildTarExport(t *testing.T, sb integration.Sandbox) {
 	dir := createTestProject(t)
-	out, err := buildCmd(sb, withArgs(fmt.Sprintf("--output=type=tar,dest=%s/result.tar", dir), dir))
+	outdir := path.Join(dir, "out")
+	out, err := buildCmd(sb, withArgs(fmt.Sprintf("--output=type=tar,dest=%s/result.tar", outdir), dir))
 	require.NoError(t, err, string(out))
 
-	dt, err := os.ReadFile(fmt.Sprintf("%s/result.tar", dir))
+	dt, err := os.ReadFile(fmt.Sprintf("%s/result.tar", outdir))
 	require.NoError(t, err)
 	m, err := testutil.ReadTarToMap(dt, false)
 	require.NoError(t, err)