feat: enable cross-arch image building (#457)

Author: reubeno

internal/app/azldev/cmds/image/build.go

@@ -31,6 +31,10 @@ type ImageBuildOptions struct {
 	// NoRemoteRepoGpgCheck disables GPG checking for all remote repositories
 	// specified via RemoteRepoPaths.
 	NoRemoteRepoGpgCheck bool
+
+	// TargetArch specifies the target architecture to build for (e.g., "x86_64" or "aarch64").
+	// If left empty, the host architecture will be used.
+	TargetArch ImageArch
 }
 
 // ImageBuildResult summarizes the results of building an image.
@@ -45,6 +49,45 @@ type ImageBuildResult struct {
 	ArtifactPaths []string `json:"artifactPaths" table:"Artifact Paths"`
 }
 
+// ImageArch represents the architecture of an image, such as "x86_64" or "aarch64".
+type ImageArch string
+
+const (
+	// ImageArchDefault represents the default architecture (i.e., the host architecture).
+	ImageArchDefault ImageArch = ""
+
+	// ImageArchX86_64 represents the x86_64 architecture.
+	ImageArchX86_64 ImageArch = "x86_64"
+
+	// ImageArchAarch64 represents the aarch64 (a.k.a. arm64) architecture.
+	ImageArchAarch64 ImageArch = "aarch64"
+)
+
+func (f *ImageArch) String() string {
+	return string(*f)
+}
+
+// Parses the architecture from a string; used by command-line parser.
+func (f *ImageArch) Set(value string) error {
+	switch value {
+	case "x86_64":
+		*f = ImageArchX86_64
+	case "aarch64":
+		*f = ImageArchAarch64
+	case "":
+		*f = ImageArchDefault
+	default:
+		return fmt.Errorf("unsupported architecture: %s", value)
+	}
+
+	return nil
+}
+
+// Returns a descriptive string used in command-line help.
+func (f *ImageArch) Type() string {
+	return "arch"
+}
+
 func buildOnAppInit(_ *azldev.App, parentCmd *cobra.Command) {
 	parentCmd.AddCommand(NewImageBuildCmd())
 }
@@ -71,6 +114,8 @@ This command invokes kiwi-ng via sudo to build the image.`,
 		ValidArgsFunction: generateImageNameCompletions,
 	}
 
+	cmd.Flags().Var(&options.TargetArch, "arch",
+		"Target architecture to build for (e.g., x86_64 or aarch64). Defaults to the host architecture if not specified)")
 	cmd.Flags().StringArrayVar(&options.LocalRepoPaths, "local-repo", []string{},
 		"Paths to local repositories to include during build (can be specified multiple times)")
 	cmd.Flags().StringArrayVar(&options.RemoteRepoPaths, "remote-repo", []string{},
@@ -193,6 +238,10 @@ func createKiwiRunner(
 		runner.WithProfile(imageConfig.Definition.Profile)
 	}
 
+	if options.TargetArch != "" {
+		runner.WithTargetArch(string(options.TargetArch))
+	}
+
 	for _, repoURI := range options.RemoteRepoPaths {
 		if err := runner.AddRemoteRepo(repoURI); err != nil {
 			return nil, fmt.Errorf("invalid remote repository:\n%w", err)

internal/utils/kiwi/kiwi.go

@@ -70,6 +70,10 @@ type Runner struct {
 
 	// profile is the optional kiwi profile to use when building the image.
 	profile string
+
+	// targetArch is the optional target architecture to build for (e.g., "x86_64" or "aarch64"). If left
+	// empty, the host architecture will be used.
+	targetArch string
 }
 
 // NewRunner constructs a new [Runner] that can be used to invoke kiwi-ng.
@@ -82,6 +86,7 @@ func NewRunner(ctx opctx.Ctx, descriptionDir string) *Runner {
 		descriptionDir:     descriptionDir,
 		remoteRepoGPGCheck: true, // GPG checking enabled by default
 		profile:            "",
+		targetArch:         "",
 	}
 }
 
@@ -97,6 +102,7 @@ func (r *Runner) Clone() *Runner {
 		remoteRepoPaths:    deep.MustCopy(r.remoteRepoPaths),
 		remoteRepoGPGCheck: r.remoteRepoGPGCheck,
 		profile:            r.profile,
+		targetArch:         r.targetArch,
 	}
 }
 
@@ -122,6 +128,14 @@ func (r *Runner) WithProfile(profile string) *Runner {
 	return r
 }
 
+// WithTargetArch sets the target architecture to build for (e.g., "x86_64" or "aarch64").
+// If left empty, the host architecture will be used.
+func (r *Runner) WithTargetArch(arch string) *Runner {
+	r.targetArch = arch
+
+	return r
+}
+
 // RemoteRepoGPGCheck returns whether GPG checking is enabled for remote repositories.
 func (r *Runner) RemoteRepoGPGCheck() bool {
 	return r.remoteRepoGPGCheck
@@ -185,6 +199,11 @@ func (r *Runner) Profile() string {
 	return r.profile
 }
 
+// TargetArch retrieves the target architecture configured for this [Runner].
+func (r *Runner) TargetArch() string {
+	return r.targetArch
+}
+
 // Build invokes kiwi-ng via sudo to build an image.
 func (r *Runner) Build(ctx context.Context) error {
 	if r.descriptionDir == "" {
@@ -209,6 +228,10 @@ func (r *Runner) Build(ctx context.Context) error {
 		"--loglevel", logLevel,
 	}
 
+	if r.targetArch != "" {
+		kiwiArgs = append(kiwiArgs, "--target-arch", r.targetArch)
+	}
+
 	if r.profile != "" {
 		kiwiArgs = append(kiwiArgs, "--profile", r.profile)
 	}