Function areSubcommandsSupported

cmd/docker/docker.go:708–730

Check recursively so that, e.g., `docker stack ls` returns the same output as `docker stack`

(cmd *cobra.Command, details versionDetails)

// Check recursively so that, e.g., `docker stack ls` returns the same output as `docker stack`
func areSubcommandsSupported(cmd *cobra.Command, details versionDetails) error {
	// Check recursively so that, e.g., `docker stack ls` returns the same output as `docker stack`
	for curr := cmd; curr != nil; curr = curr.Parent() {
		// Important: in the code below, calls to "details.CurrentVersion()" and
		// "details.ServerInfo()" are deliberately executed inline to make them
		// be executed "lazily". This is to prevent making a connection with the
		// daemon to perform a "ping" (even for commands that do not require a
		// daemon connection).
		//
		// See commit b39739123b845f872549e91be184cc583f5b387c for details.

		if cmdVersion, ok := curr.Annotations["version"]; ok && versions.LessThan(details.CurrentVersion(), cmdVersion) {
			return fmt.Errorf("%s requires API version %s, but the Docker daemon API version is %s", cmd.CommandPath(), cmdVersion, details.CurrentVersion())
		}
		if ost, ok := curr.Annotations["ostype"]; ok && details.ServerInfo().OSType != "" && ost != details.ServerInfo().OSType {
			return fmt.Errorf("%s is only supported on a Docker daemon running on %s, but the Docker daemon is running on %s", cmd.CommandPath(), ost, details.ServerInfo().OSType)
		}
		if _, ok := curr.Annotations["experimental"]; ok && !details.ServerInfo().HasExperimental {
			return fmt.Errorf("%s is only supported on a Docker daemon with experimental features enabled", cmd.CommandPath())
		}
	}
	return nil
}

func getFlagAnnotation(f *pflag.Flag, annotation string) string {
	if value, ok := f.Annotations[annotation]; ok && len(value) == 1 {