implement install script and brew cask for linux/macos

cli/azd/pkg/update/manager.go

@@ -33,6 +33,8 @@ const (
 	stableVersionURL = "https://aka.ms/azure-dev/versions/cli/latest"
 	// blobBaseURL is the base URL for Azure Blob Storage where azd binaries are hosted.
 	blobBaseURL = "https://azuresdkartifacts.z5.web.core.windows.net/azd/standalone/release"
+	// installShScriptURL is the shell install script for azd on Linux/macOS.
+	installShScriptURL = "https://aka.ms/install-azd.sh"
 )
 
 // VersionInfo holds the result of a version check.
@@ -271,12 +273,17 @@ func (m *Manager) Update(ctx context.Context, cfg *UpdateConfig, writer io.Write
 
 	switch installedBy {
 	case installer.InstallTypeBrew:
-		return m.updateViaPackageManager(ctx, "brew", []string{"upgrade", "azure/azd/azd"}, writer)
+		return m.updateViaBrew(ctx, cfg, writer)
 	case installer.InstallTypeWinget:
 		return m.updateViaPackageManager(ctx, "winget", []string{"upgrade", "Microsoft.Azd"}, writer)
 	case installer.InstallTypeChoco:
 		return m.updateViaPackageManager(ctx, "choco", []string{"upgrade", "azd"}, writer)
-	case installer.InstallTypePs, installer.InstallTypeSh, installer.InstallTypeDeb,
+	case installer.InstallTypeSh:
+		if runtime.GOOS == "windows" {
+			return m.updateViaMSI(ctx, cfg, writer)
+		}
+		return m.updateViaInstallScript(ctx, cfg, writer)
+	case installer.InstallTypePs, installer.InstallTypeDeb,
 		installer.InstallTypeRpm, installer.InstallTypeUnknown:
 		if runtime.GOOS == "windows" {
 			return m.updateViaMSI(ctx, cfg, writer)
@@ -290,6 +297,144 @@ func (m *Manager) Update(ctx context.Context, cfg *UpdateConfig, writer io.Write
 	}
 }
 
+func (m *Manager) updateViaBrew(ctx context.Context, cfg *UpdateConfig, writer io.Writer) error {
+	fmt.Fprintf(writer, "Checking Homebrew cask installation...\n")
+
+	// Determine which cask is currently installed by checking `brew list --cask`.
+	listArgs := exec.NewRunArgs("brew", "list", "--cask")
+	listResult, err := m.commandRunner.Run(ctx, listArgs)
+	if err != nil {
+		log.Printf("brew list --cask failed: %v", err)
+	}
+
+	caskOutput := ""
+	if err == nil {
+		caskOutput = listResult.Stdout
+	}
+
+	hasAzd := false
+	hasAzdDaily := false
+	for line := range strings.SplitSeq(caskOutput, "\n") {
+		name := strings.TrimSpace(line)
+		if name == "azd@daily" {
+			hasAzdDaily = true
+		} else if name == "azd" {
+			hasAzd = true
+		}
+	}
+
+	targetChannel := cfg.Channel
+
+	if !hasAzd && !hasAzdDaily {
+		// azd is not installed as a cask (formula install or other).
+		// Uninstall the non-cask version and install the correct cask.
+		fmt.Fprintf(writer, "azd is not installed as a Homebrew cask. Reinstalling as cask...\n")
+		if err := m.updateViaPackageManager(ctx, "brew", []string{"uninstall", "azd"}, writer); err != nil {
+			log.Printf("brew uninstall azd failed: %v", err)
+		}
+		switch targetChannel {
+		case ChannelStable:
+			return m.updateViaPackageManager(ctx, "brew", []string{"install", "--cask", "azure/azd/azd"}, writer)
+		case ChannelDaily:
+			return m.updateViaPackageManager(ctx, "brew", []string{"install", "--cask", "azure/azd/azd@daily"}, writer)
+		default:
+			return fmt.Errorf("unsupported channel: %s", targetChannel)
+		}
+	}
+
+	// Determine if the user is switching channels.
+	currentlyDaily := hasAzdDaily
+	currentlyStable := hasAzd
+
+	if currentlyDaily && targetChannel == ChannelStable {
+		// Switching from daily to stable
+		fmt.Fprintf(writer, "Switching from daily to stable channel...\n")
+		if err := m.updateViaPackageManager(ctx, "brew", []string{"uninstall", "--cask", "azd@daily"}, writer); err != nil {
+			return err
+		}
+		return m.updateViaPackageManager(ctx, "brew", []string{"install", "--cask", "azure/azd/azd"}, writer)
+	}
+
+	if currentlyStable && targetChannel == ChannelDaily {
+		// Switching from stable to daily
+		fmt.Fprintf(writer, "Switching from stable to daily channel...\n")
+		if err := m.updateViaPackageManager(ctx, "brew", []string{"uninstall", "--cask", "azd"}, writer); err != nil {
+			return err
+		}
+		return m.updateViaPackageManager(ctx, "brew", []string{"install", "--cask", "azure/azd/azd@daily"}, writer)
+	}
+
+	// Same channel — update in place.
+	switch targetChannel {
+	case ChannelStable:
+		fmt.Fprintf(writer, "Updating azd (stable channel)...\n")
+		return m.updateViaPackageManager(ctx, "brew", []string{"upgrade", "--cask", "azure/azd/azd"}, writer)
+	case ChannelDaily:
+		fmt.Fprintf(writer, "Updating azd (daily channel)...\n")
+		return m.updateViaPackageManager(ctx, "brew", []string{"upgrade", "--cask", "azure/azd/azd@daily"}, writer)
+	default:
+		return fmt.Errorf("unsupported channel: %s", targetChannel)
+	}
+}
+
+func (m *Manager) updateViaInstallScript(ctx context.Context, cfg *UpdateConfig, writer io.Writer) error {
+	fmt.Fprintf(writer, "Updating azd via install script...\n")
+
+	currentPath, err := currentExePath()
+	if err != nil {
+		return fmt.Errorf("failed to determine current path: %w", err)
+	}
+	installFolder := filepath.Dir(currentPath)
+
+	// Download install-azd.sh into a uniquely-created temp directory with restrictive permissions
+	scriptDir, err := os.MkdirTemp("", "azd-update-*")
+	if err != nil {
+		return newUpdateError(CodeDownloadFailed, fmt.Errorf("failed to create temp directory: %w", err))
+	}
+	defer os.RemoveAll(scriptDir)
+
+	// Restrict the temp directory so only the current user can read/write/traverse it.
+	if err := os.Chmod(scriptDir, 0o700); err != nil {
+		return newUpdateError(CodeDownloadFailed, fmt.Errorf("failed to set temp directory permissions: %w", err))
+	}
+
+	scriptPath := filepath.Join(scriptDir, "install-azd.sh")
+
+	if err := m.downloadFile(ctx, installShScriptURL, scriptPath, writer); err != nil {
+		return newUpdateError(CodeDownloadFailed, fmt.Errorf("failed to download install script: %w", err))
+	}
+
+	// Make the script executable
+	if err := os.Chmod(scriptPath, 0o500); err != nil {
+		return newUpdateError(CodeReplaceFailed, fmt.Errorf("failed to set script permissions: %w", err))
+	}
+
+	versionArg := string(cfg.Channel)
+	runArgs := exec.NewRunArgs("bash", scriptPath,
+		"--version", versionArg,
+		"--install-folder", installFolder,
+		"--symlink-folder", "",
+	)
+	runArgs = runArgs.WithStdOut(writer).WithStdErr(writer).WithInteractive(true)
+
+	log.Printf("Running install script: bash %s --version %s --install-folder %s --symlink-folder \"\"",
+		scriptPath, versionArg, installFolder)
+	fmt.Fprintf(writer, "Installing azd %s channel to %s...\n", cfg.Channel, installFolder)
+
+	result, err := m.commandRunner.Run(ctx, runArgs)
+	if err != nil {
+		return newUpdateError(CodeReplaceFailed, fmt.Errorf("install script failed: %w", err))
+	}
+
+	if result.ExitCode != 0 {
+		return newUpdateErrorf(CodeReplaceFailed,
+			"install script failed with exit code %d", result.ExitCode)
+	}
+
+	log.Printf("Install script completed successfully")
+	return nil
+}
+
 func (m *Manager) updateViaPackageManager(
 	ctx context.Context,
 	command string,
@@ -598,7 +743,12 @@ func (m *Manager) replaceBinary(ctx context.Context, newBinaryPath, currentBinar
 	// On unix, try with sudo if permission denied
 	if runtime.GOOS != "windows" {
 		log.Printf("direct replacement failed (%v), trying with sudo", err)
-		runArgs := exec.NewRunArgs("sudo", "cp", newBinaryPath, currentBinaryPath)
+		// Use "rm -f && cp" instead of plain "cp" to avoid "Text file busy" (ETXTBSY) errors.
+		// On Linux, writing to a running binary's inode fails because the kernel holds a
+		// write lock on executing files. Removing first unlinks the filename (the running
+		// process keeps the old inode alive via its fd), then cp creates a new inode.
+		shellCmd := fmt.Sprintf("rm -f %q && cp %q %q", currentBinaryPath, newBinaryPath, currentBinaryPath)
+		runArgs := exec.NewRunArgs("sudo", "sh", "-c", shellCmd)
 		runArgs = runArgs.WithInteractive(true)
 		result, sudoErr := m.commandRunner.Run(ctx, runArgs)
 		if sudoErr != nil {
@@ -766,7 +916,7 @@ func extractFromZip(archivePath, binaryName, destPath string) error {
 // IsPackageManagerInstall returns true if azd was installed via a package manager.
 func IsPackageManagerInstall() bool {
 	switch installer.InstalledBy() {
-	case installer.InstallTypeBrew, installer.InstallTypeWinget, installer.InstallTypeChoco:
+	case installer.InstallTypeWinget, installer.InstallTypeChoco:
 		return true
 	default:
 		return false