feat(server): allow specifying user-data for rebuild (#1319)

See
https://docs.hetzner.cloud/changelog#2026-01-16-server-rebuild-with-user-data

Author: phm07

docs/reference/manual/hcloud_server_rebuild.md

@@ -206,6 +206,23 @@ func detectContentType(data string) string {
 }
 
 func buildUserData(files []string) (string, error) {
+	if len(files) == 0 {
+		return "", nil
+	}
+
+	var (
+		data []byte
+		err  error
+	)
+	if len(files) == 1 {
+		if file := files[0]; file == "-" {
+			data, err = io.ReadAll(os.Stdin)
+		} else {
+			data, err = os.ReadFile(file)
+		}
+		return string(data), err
+	}
+
 	var (
 		buf = new(bytes.Buffer)
 		mp  = multipart.NewWriter(buf)
@@ -215,10 +232,6 @@ func buildUserData(files []string) (string, error) {
 	fmt.Fprint(buf, "Content-Type: multipart/mixed; boundary="+mp.Boundary()+"\r\n\r\n")
 
 	for _, file := range files {
-		var (
-			data []byte
-			err  error
-		)
 		if file == "-" {
 			data, err = io.ReadAll(os.Stdin)
 		} else {
@@ -352,22 +365,10 @@ func createOptsFromFlags(
 		publicNetConfiguration.IPv6 = primaryIPv6
 	}
 	createOpts.PublicNet = publicNetConfiguration
-	if len(userDataFiles) == 1 {
-		var data []byte
-		if userDataFiles[0] == "-" {
-			data, err = io.ReadAll(os.Stdin)
-		} else {
-			data, err = os.ReadFile(userDataFiles[0])
-		}
-		if err != nil {
-			return
-		}
-		createOpts.UserData = string(data)
-	} else if len(userDataFiles) > 1 {
-		createOpts.UserData, err = buildUserData(userDataFiles)
-		if err != nil {
-			return
-		}
+
+	createOpts.UserData, err = buildUserData(userDataFiles)
+	if err != nil {
+		return
 	}
 
 	if !flags.Changed("ssh-key") && config.OptionDefaultSSHKeys.Changed(s.Config()) {

internal/cmd/server/create.go

@@ -16,7 +16,7 @@ import (
 var RebuildCmd = base.Cmd{
 	BaseCobraCommand: func(client hcapi2.Client) *cobra.Command {
 		cmd := &cobra.Command{
-			Use:                   "rebuild [--allow-deprecated-image] --image <image> <server>",
+			Use:                   "rebuild [options] --image <image> <server>",
 			Short:                 "Rebuild a server",
 			ValidArgsFunction:     cmpl.SuggestArgs(cmpl.SuggestCandidatesF(client.Server().Names)),
 			TraverseChildren:      true,
@@ -26,8 +26,11 @@ var RebuildCmd = base.Cmd{
 		cmd.Flags().String("image", "", "ID or name of Image to rebuild from (required)")
 		_ = cmd.RegisterFlagCompletionFunc("image", cmpl.SuggestCandidatesF(client.Image().Names))
 		_ = cmd.MarkFlagRequired("image")
+
 		cmd.Flags().Bool("allow-deprecated-image", false, "Enable the use of deprecated images (default: false) (true, false)")
 
+		cmd.Flags().StringArray("user-data-from-file", []string{}, "Read user data from specified file (use - to read from stdin)")
+
 		return cmd
 	},
 	Run: func(s state.State, cmd *cobra.Command, args []string) error {
@@ -41,6 +44,8 @@ var RebuildCmd = base.Cmd{
 		}
 
 		imageIDOrName, _ := cmd.Flags().GetString("image")
+		userDataFiles, _ := cmd.Flags().GetStringArray("user-data-from-file")
+
 		// Select correct image based on Server Type architecture
 		image, _, err := s.Client().Image().GetForArchitecture(s, imageIDOrName, server.ServerType.Architecture)
 		if err != nil {
@@ -63,6 +68,15 @@ var RebuildCmd = base.Cmd{
 		opts := hcloud.ServerRebuildOpts{
 			Image: image,
 		}
+
+		if len(userDataFiles) > 0 {
+			userData, err := buildUserData(userDataFiles)
+			if err != nil {
+				return err
+			}
+			opts.UserData = &userData
+		}
+
 		result, _, err := s.Client().Server().RebuildWithResult(s, server, opts)
 		if err != nil {
 			return err