Fix yamldocs generator to accomodate nested subcommands

The script was written to only take subcommands at the first and second level
into account, but failed to find the Markdown files for extended descriptions of
subcommands at the third level, such as `docker trust key generate`, and
`docker trust key load`:

    WARN: /go/src/github.com/docker/cli/docs/reference/commandline/key_generate.md does not exist, skipping
    WARN: /go/src/github.com/docker/cli/docs/reference/commandline/key_load.md does not exist, skipping
    WARN: /go/src/github.com/docker/cli/docs/reference/commandline/signer_add.md does not exist, skipping
    WARN: /go/src/github.com/docker/cli/docs/reference/commandline/signer_remove.md does not exist, skipping

This patch updates the script to accomodate subcommands that are more deeply
nested. While at it, some minor cleaning and linting issues were also addressed.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/yamlgen/generate.go

@@ -25,6 +25,7 @@ func generateCliYaml(opts *options) error {
 	commands.AddCommands(cmd, dockerCli)
 	disableFlagsInUseLine(cmd)
 	source := filepath.Join(opts.source, descriptionSourcePath)
+	fmt.Println("Markdown source:", source)
 	if err := loadLongDescription(cmd, source); err != nil {
 		return err
 	}
@@ -50,23 +51,29 @@ func visitAll(root *cobra.Command, fn func(*cobra.Command)) {
 	fn(root)
 }
 
-func loadLongDescription(cmd *cobra.Command, path ...string) error {
-	for _, cmd := range cmd.Commands() {
-		if cmd.Name() == "" {
-			continue
-		}
-		fullpath := filepath.Join(path[0], strings.Join(append(path[1:], cmd.Name()), "_")+".md")
-
+func loadLongDescription(parentCmd *cobra.Command, path string) error {
+	for _, cmd := range parentCmd.Commands() {
 		if cmd.HasSubCommands() {
-			loadLongDescription(cmd, path[0], cmd.Name())
+			if err := loadLongDescription(cmd, path); err != nil {
+				return err
 			}
-
-		if _, err := os.Stat(fullpath); err != nil {
-			log.Printf("WARN: %s does not exist, skipping\n", fullpath)
+		}
+		name := cmd.CommandPath()
+		log.Println("INFO: Generating docs for", name)
+		if i := strings.Index(name, " "); i >= 0 {
+			// remove root command / binary name
+			name = name[i+1:]
+		}
+		if name == "" {
+			continue
+		}
+		mdFile := strings.ReplaceAll(name, " ", "_") + ".md"
+		fullPath := filepath.Join(path, mdFile)
+		content, err := ioutil.ReadFile(fullPath)
+		if os.IsNotExist(err) {
+			log.Printf("WARN: %s does not exist, skipping\n", mdFile)
 			continue
 		}
-
-		content, err := ioutil.ReadFile(fullpath)
 		if err != nil {
 			return err
 		}
@@ -95,11 +102,11 @@ func parseArgs() (*options, error) {
 func main() {
 	opts, err := parseArgs()
 	if err != nil {
-		fmt.Fprintln(os.Stderr, err.Error())
+		log.Println(err)
 	}
-	fmt.Printf("Project root: %s\n", opts.source)
-	fmt.Printf("Generating yaml files into %s\n", opts.target)
+	fmt.Println("Project root:   ", opts.source)
+	fmt.Println("YAML output dir:", opts.target)
 	if err := generateCliYaml(opts); err != nil {
-		fmt.Fprintf(os.Stderr, "Failed to generate yaml files: %s\n", err.Error())
+		log.Println("Failed to generate yaml files:", err)
 	}
 }