Add path, existingfile and existingdir types.

- Document custom types.
- Add docker example.

_examples/docker/main.go

@@ -0,0 +1,178 @@
+// nolint
+package main
+
+import (
+	"fmt"
+
+	"github.com/alecthomas/kong"
+)
+
+type AttachCmd struct {
+	DetachKeys string `help:"Override the key sequence for detaching a container"`
+	NoStdin    bool   `help:"Do not attach STDIN"`
+	SigProxy   bool   `help:"Proxy all received signals to the process" default:"true"`
+
+	Container string `arg required help:"Container ID to attach to."`
+}
+
+func (a *AttachCmd) Run() error {
+	fmt.Printf("Attaching to: %v\n", a.Container)
+	fmt.Printf("SigProxy: %v\n", a.SigProxy)
+	return nil
+}
+
+var cli struct {
+	Config       string   `help:"Location of client config files" default:"~/.docker" type:"path"`
+	Debug        bool     `short:"D" help:"Enable debug mode"`
+	Host         []string `short:"H" help:"Daemon socket(s) to connect to"`
+	LogLevel     string   `short:"l" help:"Set the logging level (debug|info|warn|error|fatal)" default:"info"`
+	TLS          bool     `help:"Use TLS; implied by --tlsverify"`
+	TLSCACert    string   `name:"tls-ca-cert" help:"Trust certs signed only by this CA" default:"~/.docker/ca.pem" type:"path"`
+	TLSCert      string   `name:"tls-cert" help:"Path to TLS certificate file" default:"~/.docker/cert.pem" type:"path"`
+	TLSKey       string   `help:"Path to TLS key file" default:"~/.docker/key.pem" type:"path"`
+	TLSVerify    bool     `help:"Use TLS and verify the remote"`
+	PrintVersion bool     `name:"version" help:"Print version information and quit"`
+
+	Attach AttachCmd `cmd help:"Attach local standard input, output, and error streams to a running container"`
+
+	Build struct {
+		Arg string `arg required`
+	} `cmd help:"Build an image from a Dockerfile"`
+	Commit struct {
+		Arg string `arg required`
+	} `cmd help:"Create a new image from a container's changes"`
+	Cp struct {
+		Arg string `arg required`
+	} `cmd help:"Copy files/folders between a container and the local filesystem"`
+	Create struct {
+		Arg string `arg required`
+	} `cmd help:"Create a new container"`
+	Deploy struct {
+		Arg string `arg required`
+	} `cmd help:"Deploy a new stack or update an existing stack"`
+	Diff struct {
+		Arg string `arg required`
+	} `cmd help:"Inspect changes to files or directories on a container's filesystem"`
+	Events struct {
+		Arg string `arg required`
+	} `cmd help:"Get real time events from the server"`
+	Exec struct {
+		Arg string `arg required`
+	} `cmd help:"Run a command in a running container"`
+	Export struct {
+		Arg string `arg required`
+	} `cmd help:"Export a container's filesystem as a tar archive"`
+	History struct {
+		Arg string `arg required`
+	} `cmd help:"Show the history of an image"`
+	Images struct {
+		Arg string `arg required`
+	} `cmd help:"List images"`
+	Import struct {
+		Arg string `arg required`
+	} `cmd help:"Import the contents from a tarball to create a filesystem image"`
+	Info struct {
+		Arg string `arg required`
+	} `cmd help:"Display system-wide information"`
+	Inspect struct {
+		Arg string `arg required`
+	} `cmd help:"Return low-level information on Docker objects"`
+	Kill struct {
+		Arg string `arg required`
+	} `cmd help:"Kill one or more running containers"`
+	Load struct {
+		Arg string `arg required`
+	} `cmd help:"Load an image from a tar archive or STDIN"`
+	Login struct {
+		Arg string `arg required`
+	} `cmd help:"Log in to a Docker registry"`
+	Logout struct {
+		Arg string `arg required`
+	} `cmd help:"Log out from a Docker registry"`
+	Logs struct {
+		Arg string `arg required`
+	} `cmd help:"Fetch the logs of a container"`
+	Pause struct {
+		Arg string `arg required`
+	} `cmd help:"Pause all processes within one or more containers"`
+	Port struct {
+		Arg string `arg required`
+	} `cmd help:"List port mappings or a specific mapping for the container"`
+	Ps struct {
+		Arg string `arg required`
+	} `cmd help:"List containers"`
+	Pull struct {
+		Arg string `arg required`
+	} `cmd help:"Pull an image or a repository from a registry"`
+	Push struct {
+		Arg string `arg required`
+	} `cmd help:"Push an image or a repository to a registry"`
+	Rename struct {
+		Arg string `arg required`
+	} `cmd help:"Rename a container"`
+	Restart struct {
+		Arg string `arg required`
+	} `cmd help:"Restart one or more containers"`
+	Rm struct {
+		Arg string `arg required`
+	} `cmd help:"Remove one or more containers"`
+	Rmi struct {
+		Arg string `arg required`
+	} `cmd help:"Remove one or more images"`
+	Run struct {
+		Arg string `arg required`
+	} `cmd help:"Run a command in a new container"`
+	Save struct {
+		Arg string `arg required`
+	} `cmd help:"Save one or more images to a tar archive (streamed to STDOUT by default)"`
+	Search struct {
+		Arg string `arg required`
+	} `cmd help:"Search the Docker Hub for images"`
+	Start struct {
+		Arg string `arg required`
+	} `cmd help:"Start one or more stopped containers"`
+	Stats struct {
+		Arg string `arg required`
+	} `cmd help:"Display a live stream of container(s) resource usage statistics"`
+	Stop struct {
+		Arg string `arg required`
+	} `cmd help:"Stop one or more running containers"`
+	Tag struct {
+		Arg string `arg required`
+	} `cmd help:"Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE"`
+	Top struct {
+		Arg string `arg required`
+	} `cmd help:"Display the running processes of a container"`
+	Unpause struct {
+		Arg string `arg required`
+	} `cmd help:"Unpause all processes within one or more containers"`
+	Update struct {
+		Arg string `arg required`
+	} `cmd help:"Update configuration of one or more containers"`
+	Version struct {
+		Arg string `arg required`
+	} `cmd help:"Show the Docker version information"`
+	Wait struct {
+		Arg string `arg required`
+	} `cmd help:"Block until one or more containers stop, then print their exit codes"`
+}
+
+func main() {
+	cmd := kong.Parse(&cli,
+		kong.Name("docker"),
+		kong.Description("A self-sufficient runtime for containers"),
+		kong.UsageOnError(),
+		kong.HelpOptions(kong.HelpPrinterOptions{
+			Compact: true,
+		}))
+	var err error
+	switch cmd {
+	case "attach <container>":
+		fmt.Println(cli.Config)
+		err = cli.Attach.Run()
+
+	default:
+		panic("unsupported command " + cmd)
+	}
+	kong.FatalIfErrorf(err)
+}