feat: upload xz compressed images (#16)

Required for Talos images:
https://www.talos.dev/v1.7/talos-guides/install/cloud-platforms/hetzner/#rescue-mode

cmd/upload.go

@@ -86,10 +86,10 @@ func init() {
 	uploadCmd.MarkFlagsMutuallyExclusive(uploadFlagImageURL, uploadFlagImagePath)
 	uploadCmd.MarkFlagsOneRequired(uploadFlagImageURL, uploadFlagImagePath)
 
-	uploadCmd.Flags().String(uploadFlagCompression, "", "Type of compression that was used on the disk image [choices: bz2]")
+	uploadCmd.Flags().String(uploadFlagCompression, "", "Type of compression that was used on the disk image [choices: bz2, xz]")
 	_ = uploadCmd.RegisterFlagCompletionFunc(
 		uploadFlagCompression,
-		cobra.FixedCompletions([]string{string(hcloudimages.CompressionBZ2)}, cobra.ShellCompDirectiveNoFileComp),
+		cobra.FixedCompletions([]string{string(hcloudimages.CompressionBZ2), string(hcloudimages.CompressionXZ)}, cobra.ShellCompDirectiveNoFileComp),
 	)
 
 	uploadCmd.Flags().String(uploadFlagArchitecture, "", "CPU architecture of the disk image [choices: x86, arm]")

hcloudimages/client.go

@@ -86,9 +86,10 @@ type Compression string
 const (
 	CompressionNone Compression = ""
 	CompressionBZ2  Compression = "bz2"
+	CompressionXZ   Compression = "xz"
 
 	// Possible future additions:
-	// zip,xz,zstd
+	// zip,zstd
 )
 
 // NewClient instantiates a new client. It requires a working [*hcloud.Client] to interact with the Hetzner Cloud API.
@@ -290,6 +291,8 @@ func (s *Client) Upload(ctx context.Context, options UploadOptions) (*hcloud.Ima
 		switch options.ImageCompression {
 		case CompressionBZ2:
 			cmd += "bzip2 -cd | "
+		case CompressionXZ:
+			cmd += "xz -cd | "
 		default:
 			return nil, fmt.Errorf("unknown compression: %q", options.ImageCompression)
 		}