main: auto-cross build for foreign architectures

cmd/image-builder/main.go

@@ -14,7 +14,6 @@ import (
 
 	"github.com/osbuild/bootc-image-builder/bib/pkg/progress"
 	"github.com/osbuild/images/pkg/arch"
-	"github.com/osbuild/images/pkg/experimentalflags"
 	"github.com/osbuild/images/pkg/imagefilter"
 	"github.com/osbuild/images/pkg/osbuild"
 	"github.com/osbuild/images/pkg/ostree"
@@ -82,7 +81,7 @@ func ostreeImageOptions(cmd *cobra.Command) (*ostree.ImageOptions, error) {
 	}, nil
 }
 
-func cmdManifestWrapper(pbar progress.ProgressBar, cmd *cobra.Command, args []string, w io.Writer, archChecker func(string) error) (*imagefilter.Result, error) {
+func cmdManifestWrapper(pbar progress.ProgressBar, cmd *cobra.Command, args []string, w io.Writer, needBootstrap func(string) bool) (*imagefilter.Result, error) {
 	dataDir, err := cmd.Flags().GetString("data-dir")
 	if err != nil {
 		return nil, err
@@ -157,13 +156,6 @@ func cmdManifestWrapper(pbar progress.ProgressBar, cmd *cobra.Command, args []st
 	if err != nil {
 		return nil, err
 	}
-	// assume that users with the "bootstrap" flag want cross building
-	// and skip arch checks then
-	if archChecker != nil && experimentalflags.String("bootstrap") == "" {
-		if err := archChecker(img.Arch.Name()); err != nil {
-			return nil, err
-		}
-	}
 	if len(img.ImgType.Exports()) > 1 {
 		return nil, fmt.Errorf("image %q has multiple exports: this is current unsupport: please report this as a bug", basenameFor(img, ""))
 	}
@@ -178,6 +170,13 @@ func cmdManifestWrapper(pbar progress.ProgressBar, cmd *cobra.Command, args []st
 
 		ForceRepos: forceRepos,
 	}
+	if needBootstrap != nil {
+		opts.UseBootstrapContainer = needBootstrap(img.Arch.Name())
+	}
+	if opts.UseBootstrapContainer {
+		fmt.Fprintf(os.Stderr, "WARNING: using experimental cross-architecture building to build %q\n", img.Arch.Name())
+	}
+
 	err = generateManifest(dataDir, extraRepos, img, w, opts)
 	return img, err
 }
@@ -244,11 +243,8 @@ func cmdBuild(cmd *cobra.Command, args []string) error {
 
 	var mf bytes.Buffer
 	// XXX: check env here, i.e. if user is root and osbuild is installed
-	res, err := cmdManifestWrapper(pbar, cmd, args, &mf, func(archStr string) error {
+	res, err := cmdManifestWrapper(pbar, cmd, args, &mf, func(archStr string) bool {
-		if archStr != arch.Current().String() {
+		return archStr != arch.Current().String()
-			return fmt.Errorf("cannot build for arch %q from %q", archStr, arch.Current().String())
-		}
-		return nil
 	})
 	if err != nil {
 		return err

cmd/image-builder/main_test.go

@@ -814,7 +814,7 @@ func TestManifestOverrideRepo(t *testing.T) {
 	// DNF error occurred: RepoError: There was a problem reading a repository: Failed to download metadata for repo '9828718901ab404ac1b600157aec1a8b19f4b2139e7756f347fb0ecc06c92929' [forced repo#0 xxx.abcdefgh-no-such-host.com/repo: http://xxx.abcdefgh-no-such-host.com/repo]: Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried`
 }
 
-func TestBuildCrossArchCheckSkippedOnExperimentalBuildroot(t *testing.T) {
+func TestBuildCrossArchSmoke(t *testing.T) {
 	if testing.Short() {
 		t.Skip("manifest generation takes a while")
 	}
@@ -826,31 +826,42 @@ func TestBuildCrossArchCheckSkippedOnExperimentalBuildroot(t *testing.T) {
 	defer restore()
 
 	tmpdir := t.TempDir()
-	for _, withExperimentalBootstrapEnv := range []bool{false, true} {
+	for _, withCrossArch := range []bool{false, true} {
-		if withExperimentalBootstrapEnv {
+		cmd := []string{
-			t.Setenv("IMAGE_BUILDER_EXPERIMENTAL", "bootstrap=ghcr.io/mvo5/fedora-buildroot:41")
-		}
-		restore = main.MockOsArgs([]string{
 			"build",
 			"qcow2",
 			"--distro", "centos-9",
 			"--cache", tmpdir,
-			"--arch=s390x",
 			"--output-dir", tmpdir,
-		})
+		}
+		if withCrossArch {
+			cmd = append(cmd, "--arch=aarch64")
+		}
+		restore = main.MockOsArgs(cmd)
 		defer restore()
 
 		script := makeFakeOsbuildScript()
 		fakeOsbuildCmd := testutil.MockCommand(t, "osbuild", script)
 		defer fakeOsbuildCmd.Restore()
 
-		err := main.Run()
+		var err error
-		if withExperimentalBootstrapEnv {
+		_, stderr := testutil.CaptureStdio(t, func() {
-			assert.NoError(t, err)
+			err = main.Run()
-			require.Equal(t, 1, len(fakeOsbuildCmd.Calls()))
+		})
+		assert.NoError(t, err)
+
+		manifest, err := os.ReadFile(fakeOsbuildCmd.Path() + ".stdin")
+		assert.NoError(t, err)
+		pipelines, err := manifesttest.PipelineNamesFrom(manifest)
+		assert.NoError(t, err)
+		crossArchPipeline := "bootstrap-buildroot"
+		crossArchWarning := `WARNING: using experimental cross-architecture building to build "aarch64"`
+		if withCrossArch {
+			assert.Contains(t, pipelines, crossArchPipeline)
+			assert.Contains(t, stderr, crossArchWarning)
 		} else {
-			assert.EqualError(t, err, `cannot build for arch "s390x" from "x86_64"`)
+			assert.NotContains(t, pipelines, crossArchPipeline)
-			require.Equal(t, 0, len(fakeOsbuildCmd.Calls()))
+			assert.NotContains(t, stderr, crossArchWarning)
 		}
 	}
 }

cmd/image-builder/manifest.go

@@ -25,7 +25,8 @@ type manifestOptions struct {
 	RpmDownloader  osbuild.RpmDownloader
 	WithSBOM       bool
 
-	ForceRepos []string
+	ForceRepos            []string
+	UseBootstrapContainer bool
 }
 
 func sbomWriter(outputDir, filename string, content io.Reader) error {
@@ -51,8 +52,9 @@ func generateManifest(dataDir string, extraRepos []string, img *imagefilter.Resu
 	}
 	// XXX: add --rpmmd/cachedir option like bib
 	manifestGenOpts := &manifestgen.Options{
-		Output:        output,
+		Output:                output,
-		RpmDownloader: opts.RpmDownloader,
+		RpmDownloader:         opts.RpmDownloader,
+		UseBootstrapContainer: opts.UseBootstrapContainer,
 	}
 	if opts.WithSBOM {
 		outputDir := basenameFor(img, opts.OutputDir)