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moby--moby/cli/cli.go
Tibor Vass 96ce3a194a cli: new daemon command and new cli package
This patch creates a new cli package that allows to combine both client
and daemon commands (there is only one daemon command: docker daemon).

The `-d` and `--daemon` top-level flags are deprecated and a special
message is added to prompt the user to use `docker daemon`.

Providing top-level daemon-specific flags for client commands result
in an error message prompting the user to use `docker daemon`.

This patch does not break any old but correct usages.

This also makes `-d` and `--daemon` flags, as well as the `daemon`
command illegal in client-only binaries.

Signed-off-by: Tibor Vass <tibor@docker.com>
2015-07-23 19:44:46 -04:00

200 lines
4.5 KiB
Go

package cli
import (
"errors"
"fmt"
"io"
"os"
"reflect"
"strings"
flag "github.com/docker/docker/pkg/mflag"
)
// Cli represents a command line interface.
type Cli struct {
Stderr io.Writer
handlers []Handler
Usage func()
}
// Handler holds the different commands Cli will call
// It should have methods with names starting with `Cmd` like:
// func (h myHandler) CmdFoo(args ...string) error
type Handler interface{}
// Initializer can be optionally implemented by a Handler to
// initialize before each call to one of its commands.
type Initializer interface {
Initialize() error
}
// New instantiates a ready-to-use Cli.
func New(handlers ...Handler) *Cli {
// make the generic Cli object the first cli handler
// in order to handle `docker help` appropriately
cli := new(Cli)
cli.handlers = append([]Handler{cli}, handlers...)
return cli
}
// initErr is an error returned upon initialization of a handler implementing Initializer.
type initErr struct{ error }
func (err initErr) Error() string {
return err.Error()
}
func (cli *Cli) command(args ...string) (func(...string) error, error) {
for _, c := range cli.handlers {
if c == nil {
continue
}
camelArgs := make([]string, len(args))
for i, s := range args {
if len(s) == 0 {
return nil, errors.New("empty command")
}
camelArgs[i] = strings.ToUpper(s[:1]) + strings.ToLower(s[1:])
}
methodName := "Cmd" + strings.Join(camelArgs, "")
method := reflect.ValueOf(c).MethodByName(methodName)
if method.IsValid() {
if c, ok := c.(Initializer); ok {
if err := c.Initialize(); err != nil {
return nil, initErr{err}
}
}
return method.Interface().(func(...string) error), nil
}
}
return nil, errors.New("command not found")
}
// Run executes the specified command.
func (cli *Cli) Run(args ...string) error {
if len(args) > 1 {
command, err := cli.command(args[:2]...)
switch err := err.(type) {
case nil:
return command(args[2:]...)
case initErr:
return err.error
}
}
if len(args) > 0 {
command, err := cli.command(args[0])
switch err := err.(type) {
case nil:
return command(args[1:]...)
case initErr:
return err.error
}
cli.noSuchCommand(args[0])
}
return cli.CmdHelp()
}
func (cli *Cli) noSuchCommand(command string) {
if cli.Stderr == nil {
cli.Stderr = os.Stderr
}
fmt.Fprintf(cli.Stderr, "docker: '%s' is not a docker command.\nSee 'docker --help'.\n", command)
os.Exit(1)
}
// CmdHelp displays information on a Docker command.
//
// If more than one command is specified, information is only shown for the first command.
//
// Usage: docker help COMMAND or docker COMMAND --help
func (cli *Cli) CmdHelp(args ...string) error {
if len(args) > 1 {
command, err := cli.command(args[:2]...)
switch err := err.(type) {
case nil:
command("--help")
return nil
case initErr:
return err.error
}
}
if len(args) > 0 {
command, err := cli.command(args[0])
switch err := err.(type) {
case nil:
command("--help")
return nil
case initErr:
return err.error
}
cli.noSuchCommand(args[0])
}
if cli.Usage == nil {
flag.Usage()
} else {
cli.Usage()
}
return nil
}
// Subcmd is a subcommand of the main "docker" command.
// A subcommand represents an action that can be performed
// from the Docker command line client.
//
// To see all available subcommands, run "docker --help".
func Subcmd(name string, synopses []string, description string, exitOnError bool) *flag.FlagSet {
var errorHandling flag.ErrorHandling
if exitOnError {
errorHandling = flag.ExitOnError
} else {
errorHandling = flag.ContinueOnError
}
flags := flag.NewFlagSet(name, errorHandling)
flags.Usage = func() {
flags.ShortUsage()
flags.PrintDefaults()
}
flags.ShortUsage = func() {
options := ""
if flags.FlagCountUndeprecated() > 0 {
options = " [OPTIONS]"
}
if len(synopses) == 0 {
synopses = []string{""}
}
// Allow for multiple command usage synopses.
for i, synopsis := range synopses {
lead := "\t"
if i == 0 {
// First line needs the word 'Usage'.
lead = "Usage:\t"
}
if synopsis != "" {
synopsis = " " + synopsis
}
fmt.Fprintf(flags.Out(), "\n%sdocker %s%s%s", lead, name, options, synopsis)
}
fmt.Fprintf(flags.Out(), "\n\n%s\n", description)
}
return flags
}
// An StatusError reports an unsuccessful exit by a command.
type StatusError struct {
Status string
StatusCode int
}
func (e StatusError) Error() string {
return fmt.Sprintf("Status: %s, Code: %d", e.Status, e.StatusCode)
}