fix: Don't crash when reading header if 'main.tf' not found (#235)

Signed-off-by: Khosrow Moossavi <khos2ow@gmail.com>

cmd/root.go

@@ -13,11 +13,13 @@ var settings = print.NewSettings()
 var options = module.NewOptions()
 
 var rootCmd = &cobra.Command{
-	Args:    cobra.NoArgs,
-	Use:     "terraform-docs",
-	Short:   "A utility to generate documentation from Terraform modules in various output formats",
-	Long:    "A utility to generate documentation from Terraform modules in various output formats",
-	Version: version.Version(),
+	Args:          cobra.NoArgs,
+	Use:           "terraform-docs",
+	Short:         "A utility to generate documentation from Terraform modules in various output formats",
+	Long:          "A utility to generate documentation from Terraform modules in various output formats",
+	Version:       version.Version(),
+	SilenceUsage:  true,
+	SilenceErrors: true,
 	PersistentPreRun: func(cmd *cobra.Command, args []string) {
 		oppositeBool := func(name string) bool {
 			val, _ := cmd.Flags().GetBool(name)
@@ -67,7 +69,10 @@ func init() {
 // Execute adds all child commands to the root command and sets flags appropriately.
 // This is called by main.main(). It only needs to happen once to the rootCmd.
 func Execute() error {
-	return rootCmd.Execute()
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Printf("Error: %s\n", err.Error())
+	}
+	return nil
 }
 
 // RootCmd represents the base command when called without any subcommands

internal/module/module.go

@@ -72,7 +72,10 @@ func loadHeader(options *Options) (string, error) {
 	filename := filepath.Join(options.Path, options.HeaderFromFile)
 	_, err := ioutil.ReadFile(filename)
 	if err != nil {
-		return "", err
+		if options.HeaderFromFile != "main.tf" {
+			return "", err // user explicitly asked for a file which doesn't exist
+		}
+		return "", nil // absorb the error to not break workflow of users who don't have 'main.tf at all
 	}
 	lines := reader.Lines{
 		FileName: filename,

internal/module/module_test.go

@@ -75,6 +75,13 @@ func TestLoadHeader(t *testing.T) {
 			expected: "Custom Header:\n\nExample of 'foo_bar' module in `foo_bar.tf`.\n\n- list item 1\n- list item 2",
 			wantErr:  false,
 		},
+		{
+			name:     "load module header from path",
+			path:     "no-inputs",
+			header:   "main.tf",
+			expected: "",
+			wantErr:  false,
+		},
 		{
 			name:     "load module header from path",
 			path:     "full-example",