kotovalexarian-likes-github
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moby--moby
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Factored out docker/rcli (remote cli protocol), docker/fake (mocking utilities) and docker/future (real utilities which don't yet fit in the core)

This commit is contained in:
Solomon Hykes 2013-01-24 20:01:32 -08:00
parent 553ca56d7e
commit f3ffba7afe
7 changed files with 344 additions and 255 deletions
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15
docker/docker.go
View File

@ -1,14 +1,12 @@
package main
import (
"github.com/dotcloud/docker/rcli"
"io"
"encoding/json"
"log"
"os"
"net"
"fmt"
"syscall"
"unsafe"
"unsafe"
)
@ -172,17 +170,10 @@ func main() {
}
defer Restore(0, oldState)
}
cmd, err := json.Marshal(os.Args[1:])
conn, err := rcli.CallTCP(os.Getenv("DOCKER"), os.Args[1:]...)
if err != nil {
Fatal(err)
}
conn, err := net.Dial("tcp", os.Getenv("DOCKER"))
if err != nil {
Fatal(err)
}
if _, err := fmt.Fprintln(conn, string(cmd)); err != nil {
Fatal(err)
}
go func() {
if _, err := io.Copy(os.Stdout, conn); err != nil {
Fatal(err)

293
dockerd/dockerd.go
View File

@ -1,64 +1,56 @@
package main
import (
"github.com/dotcloud/docker/rcli"
"github.com/dotcloud/docker/fake"
"github.com/dotcloud/docker/future"
"bufio"
"errors"
"log"
"io"
"io/ioutil"
"net"
"net/url"
"net/http"
"os/exec"
"flag"
"reflect"
"fmt"
"github.com/kr/pty"
"path"
"strings"
"time"
"math/rand"
"crypto/sha256"
"bytes"
"text/tabwriter"
"sort"
"os"
"archive/tar"
"encoding/json"
"time"
)
func (docker *Docker) CmdHelp(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
if len(args) == 0 {
fmt.Fprintf(stdout, "Usage: docker COMMAND [arg...]\n\nA self-sufficient runtime for linux containers.\n\nCommands:\n")
for _, cmd := range [][]interface{}{
{"run", "Run a command in a container"},
{"list", "Display a list of containers"},
{"get", "Download a tarball and create a container from it"},
{"put", "Upload a tarball and create a container from it"},
{"rm", "Remove containers"},
{"wait", "Wait for the state of a container to change"},
{"stop", "Stop a running container"},
{"logs", "Fetch the logs of a container"},
{"diff", "Inspect changes on a container's filesystem"},
{"fork", "Duplicate a container"},
{"attach", "Attach to the standard inputs and outputs of a running container"},
{"info", "Display system-wide information"},
{"web", "Generate a web UI"},
} {
fmt.Fprintf(stdout, " %-10.10s%s\n", cmd...)
}
} else {
if method := docker.getMethod(args[0]); method == nil {
return errors.New("No such command: " + args[0])
} else {
method(stdin, stdout, "--help")
}
}
return nil
func (docker *Docker) Name() string {
return "docker"
}
func (docker *Docker) Help() string {
help := "Usage: docker COMMAND [arg...]\n\nA self-sufficient runtime for linux containers.\n\nCommands:\n"
for _, cmd := range [][]interface{}{
{"run", "Run a command in a container"},
{"list", "Display a list of containers"},
{"pull", "Download a tarball and create a container from it"},
{"put", "Upload a tarball and create a container from it"},
{"rm", "Remove containers"},
{"wait", "Wait for the state of a container to change"},
{"stop", "Stop a running container"},
{"logs", "Fetch the logs of a container"},
{"diff", "Inspect changes on a container's filesystem"},
{"commit", "Save the state of a container"},
{"attach", "Attach to the standard inputs and outputs of a running container"},
{"info", "Display system-wide information"},
{"web", "Generate a web UI"},
} {
help += fmt.Sprintf(" %-10.10s%s\n", cmd...)
}
return help
}
func (docker *Docker) CmdList(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout, "list", "[OPTIONS] [NAME]", "List containers")
flags := rcli.Subcmd(stdout, "list", "[OPTIONS] [NAME]", "List containers")
limit := flags.Int("l", 0, "Only show the N most recent versions of each name")
quiet := flags.Bool("q", false, "only show numeric IDs")
flags.Parse(args)
@ -91,7 +83,7 @@ func (docker *Docker) CmdList(stdin io.ReadCloser, stdout io.Writer, args ...str
for idx, field := range []string{
/* NAME */ container.Name,
/* ID */ container.Id,
/* CREATED */ humanDuration(time.Now().Sub(container.Created)) + " ago",
/* CREATED */ future.HumanDuration(time.Now().Sub(container.Created)) + " ago",
/* SOURCE */ container.Source,
/* SIZE */ fmt.Sprintf("%.1fM", float32(container.Size) / 1024 / 1024),
/* CHANGES */ fmt.Sprintf("%.1fM", float32(container.BytesChanged) / 1024 / 1024),
@ -130,7 +122,7 @@ func (docker *Docker) findContainer(name string) (*Container, bool) {
func (docker *Docker) CmdRm(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout, "rm", "[OPTIONS] CONTAINER", "Remove a container")
flags := rcli.Subcmd(stdout, "rm", "[OPTIONS] CONTAINER", "Remove a container")
if err := flags.Parse(args); err != nil {
return nil
}
@ -142,7 +134,7 @@ func (docker *Docker) CmdRm(stdin io.ReadCloser, stdout io.Writer, args ...strin
return nil
}
func (docker *Docker) CmdGet(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
func (docker *Docker) CmdPull(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
if len(args) < 1 {
return errors.New("Not enough arguments")
}
@ -162,8 +154,8 @@ func (docker *Docker) CmdPut(stdin io.ReadCloser, stdout io.Writer, args ...stri
return nil
}
func (docker *Docker) CmdFork(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout,
func (docker *Docker) CmdCommit(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := rcli.Subcmd(stdout,
"fork", "[OPTIONS] CONTAINER [DEST]",
"Duplicate a container")
// FIXME "-r" to reset changes in the new container
@ -187,7 +179,7 @@ func (docker *Docker) CmdFork(stdin io.ReadCloser, stdout io.Writer, args ...str
}
func (docker *Docker) CmdTar(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout,
flags := rcli.Subcmd(stdout,
"tar", "CONTAINER",
"Stream the contents of a container as a tar archive")
if err := flags.Parse(args); err != nil {
@ -196,13 +188,13 @@ func (docker *Docker) CmdTar(stdin io.ReadCloser, stdout io.Writer, args ...stri
name := flags.Arg(0)
if _, exists := docker.findContainer(name); exists {
// Stream the entire contents of the container (basically a volatile snapshot)
return WriteFakeTar(stdout)
return fake.WriteFakeTar(stdout)
}
return errors.New("No such container: " + name)
}
func (docker *Docker) CmdDiff(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout,
flags := rcli.Subcmd(stdout,
"diff", "CONTAINER [OPTIONS]",
"Inspect changes on a container's filesystem")
fl_diff := flags.Bool("d", true, "Show changes in diff format")
@ -238,7 +230,7 @@ index 2dae694..e43caca 100644
--- a/dockerd/dockerd.go
+++ b/dockerd/dockerd.go
@@ -158,6 +158,7 @@ func (docker *Docker) CmdDiff(stdin io.ReadCloser, stdout io.Writer, args ...str
flags := Subcmd(stdout,
flags := rcli.Subcmd(stdout,
"diff", "CONTAINER [OPTIONS]",
"Inspect changes on a container's filesystem")
+ fl_diff := flags.Bool("d", true, "Show changes in diff format")
@ -290,12 +282,11 @@ func (c *ByDate) Del(id string) {
func (docker *Docker) addContainer(name string, source string, size uint) *Container {
// Generate a fake random size
if size == 0 {
size = uint(rand.Int31n(142 * 1024 * 1024))
size = fake.RandomContainerSize()
}
c := &Container{
Id: randomId(),
Id: fake.RandomId(),
Name: name,
Created: time.Now(),
Source: source,
@ -330,7 +321,7 @@ func (docker *Docker) rm(id string) (*Container, error) {
func (docker *Docker) CmdLogs(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout, "logs", "[OPTIONS] CONTAINER", "Fetch the logs of a container")
flags := rcli.Subcmd(stdout, "logs", "[OPTIONS] CONTAINER", "Fetch the logs of a container")
if err := flags.Parse(args); err != nil {
return nil
}
@ -349,7 +340,7 @@ func (docker *Docker) CmdLogs(stdin io.ReadCloser, stdout io.Writer, args ...str
}
func (docker *Docker) CmdRun(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout, "run", "[OPTIONS] CONTAINER COMMAND [ARG...]", "Run a command in a container")
flags := rcli.Subcmd(stdout, "run", "[OPTIONS] CONTAINER COMMAND [ARG...]", "Run a command in a container")
fl_attach := flags.Bool("a", false, "Attach stdin and stdout")
if err := flags.Parse(args); err != nil {
return nil
@ -396,60 +387,21 @@ func startCommand(cmd *exec.Cmd, interactive bool) (io.WriteCloser, io.ReadClose
return stdin, stdout, nil
}
func (docker *Docker) ListenAndServeTCP(addr string) error {
listener, err := net.Listen("tcp", addr)
if err != nil {
return err
}
defer listener.Close()
for {
if conn, err := listener.Accept(); err != nil {
return err
} else {
go func() {
if err := docker.serve(conn); err != nil {
log.Printf("Error: " + err.Error() + "\n")
fmt.Fprintf(conn, "Error: " + err.Error() + "\n")
}
conn.Close()
}()
}
}
return nil
}
func (docker *Docker) ListenAndServeHTTP(addr string) error {
return http.ListenAndServe(addr, docker)
}
func main() {
rand.Seed(time.Now().UTC().UnixNano())
fake.Seed()
flag.Parse()
docker := New()
go func() {
if err := docker.ListenAndServeHTTP(":8080"); err != nil {
if err := rcli.ListenAndServeHTTP(":8080", docker); err != nil {
log.Fatal(err)
}
}()
if err := docker.ListenAndServeTCP(":4242"); err != nil {
if err := rcli.ListenAndServeTCP(":4242", docker); err != nil {
log.Fatal(err)
}
}
func (docker *Docker) serve(conn net.Conn) error {
r := bufio.NewReader(conn)
var args []string
if line, err := r.ReadString('\n'); err != nil {
return err
} else if err := json.Unmarshal([]byte(line), &args); err != nil {
return err
} else {
return docker.Call(ioutil.NopCloser(r), conn, args...)
}
return nil
}
func New() *Docker {
return &Docker{
containersByName: make(map[string]*ByDate),
@ -457,43 +409,6 @@ func New() *Docker {
}
}
type AutoFlush struct {
http.ResponseWriter
}
func (w *AutoFlush) Write(data []byte) (int, error) {
ret, err := w.ResponseWriter.Write(data)
if flusher, ok := w.ResponseWriter.(http.Flusher); ok {
flusher.Flush()
}
return ret, err
}
func (docker *Docker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
cmd, args := URLToCall(r.URL)
if err := docker.Call(r.Body, &AutoFlush{w}, append([]string{cmd}, args...)...); err != nil {
fmt.Fprintf(w, "Error: " + err.Error() + "\n")
}
}
func (docker *Docker) Call(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := flag.NewFlagSet("docker", flag.ContinueOnError)
flags.SetOutput(stdout)
flags.Usage = func() { docker.CmdHelp(stdin, stdout) }
if err := flags.Parse(args); err != nil {
return err
}
cmd := flags.Arg(0)
log.Printf("%s\n", strings.Join(append(append([]string{"docker"}, cmd), args[1:]...), " "))
if cmd == "" {
cmd = "help"
}
method := docker.getMethod(cmd)
if method != nil {
return method(stdin, stdout, args[1:]...)
}
return errors.New("No such command: " + cmd)
}
func (docker *Docker) CmdMirror(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
_, err := io.Copy(stdout, stdin)
@ -517,7 +432,7 @@ func (docker *Docker) CmdDebug(stdin io.ReadCloser, stdout io.Writer, args ...st
}
func (docker *Docker) CmdWeb(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := Subcmd(stdout, "web", "[OPTIONS]", "A web UI for docker")
flags := rcli.Subcmd(stdout, "web", "[OPTIONS]", "A web UI for docker")
showurl := flags.Bool("u", false, "Return the URL of the web UI")
if err := flags.Parse(args); err != nil {
return nil
@ -534,25 +449,6 @@ func (docker *Docker) CmdWeb(stdin io.ReadCloser, stdout io.Writer, args ...stri
return nil
}
func (docker *Docker) getMethod(name string) Cmd {
methodName := "Cmd"+strings.ToUpper(name[:1])+strings.ToLower(name[1:])
method, exists := reflect.TypeOf(docker).MethodByName(methodName)
if !exists {
return nil
}
return func(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
ret := method.Func.CallSlice([]reflect.Value{
reflect.ValueOf(docker),
reflect.ValueOf(stdin),
reflect.ValueOf(stdout),
reflect.ValueOf(args),
})[0].Interface()
if ret == nil {
return nil
}
return ret.(error)
}
}
func Go(f func() error) chan error {
ch := make(chan error)
@ -596,8 +492,8 @@ func (c *Container) Run(command string, args []string, stdin io.ReadCloser, stdo
cmd := exec.Command(c.Cmd, c.Args...)
cmd_stdin, cmd_stdout, err := startCommand(cmd, true)
// ADD FAKE RANDOM CHANGES
c.FilesChanged = uint(rand.Int31n(42))
c.BytesChanged = uint(rand.Int31n(24 * 1024 * 1024))
c.FilesChanged = fake.RandomFilesChanged()
c.BytesChanged = fake.RandomBytesChanged()
if err != nil {
return err
}
@ -643,92 +539,3 @@ func (c *Container) CmdString() string {
return strings.Join(append([]string{c.Cmd}, c.Args...), " ")
}
type Cmd func(io.ReadCloser, io.Writer, ...string) error
type CmdMethod func(*Docker, io.ReadCloser, io.Writer, ...string) error
// Use this key to encode an RPC call into an URL,
// eg. domain.tld/path/to/method?q=get_user&q=gordon
const ARG_URL_KEY = "q"
func URLToCall(u *url.URL) (method string, args []string) {
return path.Base(u.Path), u.Query()[ARG_URL_KEY]
}
func randomBytes() io.Reader {
return bytes.NewBuffer([]byte(fmt.Sprintf("%x", rand.Int())))
}
func ComputeId(content io.Reader) (string, error) {
h := sha256.New()
if _, err := io.Copy(h, content); err != nil {
return "", err
}
return fmt.Sprintf("%x", h.Sum(nil)[:8]), nil
}
func randomId() string {
id, _ := ComputeId(randomBytes()) // can't fail
return id
}
func humanDuration(d time.Duration) string {
if seconds := int(d.Seconds()); seconds < 1 {
return "Less than a second"
} else if seconds < 60 {
return fmt.Sprintf("%d seconds", seconds)
} else if minutes := int(d.Minutes()); minutes == 1 {
return "About a minute"
} else if minutes < 60 {
return fmt.Sprintf("%d minutes", minutes)
} else if hours := int(d.Hours()); hours == 1{
return "About an hour"
} else if hours < 48 {
return fmt.Sprintf("%d hours", hours)
} else if hours < 24 * 7 * 2 {
return fmt.Sprintf("%d days", hours / 24)
} else if hours < 24 * 30 * 3 {
return fmt.Sprintf("%d weeks", hours / 24 / 7)
} else if hours < 24 * 365 * 2 {
return fmt.Sprintf("%d months", hours / 24 / 30)
}
return fmt.Sprintf("%d years", d.Hours() / 24 / 365)
}
func Subcmd(output io.Writer, name, signature, description string) *flag.FlagSet {
flags := flag.NewFlagSet(name, flag.ContinueOnError)
flags.SetOutput(output)
flags.Usage = func() {
fmt.Fprintf(output, "\nUsage: docker %s %s\n\n%s\n\n", name, signature, description)
flags.PrintDefaults()
}
return flags
}
func WriteFakeTar(dst io.Writer) error {
if data, err := FakeTar(); err != nil {
return err
} else if _, err := io.Copy(dst, data); err != nil {
return err
}
return nil
}
func FakeTar() (io.Reader, error) {
content := []byte("Hello world!\n")
buf := new(bytes.Buffer)
tw := tar.NewWriter(buf)
for _, name := range []string {"/etc/postgres/postgres.conf", "/etc/passwd", "/var/log/postgres", "/var/log/postgres/postgres.conf"} {
hdr := new(tar.Header)
hdr.Size = int64(len(content))
hdr.Name = name
if err := tw.WriteHeader(hdr); err != nil {
return nil, err
}
tw.Write([]byte(content))
}
tw.Close()
return buf, nil
}

65
fake/fake.go Normal file
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@ -0,0 +1,65 @@
package fake
import (
"github.com/dotcloud/docker/future"
"bytes"
"math/rand"
"time"
"io"
"archive/tar"
"fmt"
)
func Seed() {
rand.Seed(time.Now().UTC().UnixNano())
}
func randomBytes() io.Reader {
return bytes.NewBuffer([]byte(fmt.Sprintf("%x", rand.Int())))
}
func FakeTar() (io.Reader, error) {
content := []byte("Hello world!\n")
buf := new(bytes.Buffer)
tw := tar.NewWriter(buf)
for _, name := range []string {"/etc/postgres/postgres.conf", "/etc/passwd", "/var/log/postgres", "/var/log/postgres/postgres.conf"} {
hdr := new(tar.Header)
hdr.Size = int64(len(content))
hdr.Name = name
if err := tw.WriteHeader(hdr); err != nil {
return nil, err
}
tw.Write([]byte(content))
}
tw.Close()
return buf, nil
}
func WriteFakeTar(dst io.Writer) error {
if data, err := FakeTar(); err != nil {
return err
} else if _, err := io.Copy(dst, data); err != nil {
return err
}
return nil
}
func RandomId() string {
id, _ := future.ComputeId(randomBytes()) // can't fail
return id
}
func RandomBytesChanged() uint {
return uint(rand.Int31n(24 * 1024 * 1024))
}
func RandomFilesChanged() uint {
return uint(rand.Int31n(42))
}
func RandomContainerSize() uint {
return uint(rand.Int31n(142 * 1024 * 1024))
}

39
future/future.go Normal file
View File

@ -0,0 +1,39 @@
package future
import (
"crypto/sha256"
"io"
"fmt"
"time"
)
func ComputeId(content io.Reader) (string, error) {
h := sha256.New()
if _, err := io.Copy(h, content); err != nil {
return "", err
}
return fmt.Sprintf("%x", h.Sum(nil)[:8]), nil
}
func HumanDuration(d time.Duration) string {
if seconds := int(d.Seconds()); seconds < 1 {
return "Less than a second"
} else if seconds < 60 {
return fmt.Sprintf("%d seconds", seconds)
} else if minutes := int(d.Minutes()); minutes == 1 {
return "About a minute"
} else if minutes < 60 {
return fmt.Sprintf("%d minutes", minutes)
} else if hours := int(d.Hours()); hours == 1{
return "About an hour"
} else if hours < 48 {
return fmt.Sprintf("%d hours", hours)
} else if hours < 24 * 7 * 2 {
return fmt.Sprintf("%d days", hours / 24)
} else if hours < 24 * 30 * 3 {
return fmt.Sprintf("%d weeks", hours / 24 / 7)
} else if hours < 24 * 365 * 2 {
return fmt.Sprintf("%d months", hours / 24 / 30)
}
return fmt.Sprintf("%d years", d.Hours() / 24 / 365)
}

41
rcli/http.go Normal file
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@ -0,0 +1,41 @@
package rcli
import (
"net/http"
"net/url"
"path"
"fmt"
)
// Use this key to encode an RPC call into an URL,
// eg. domain.tld/path/to/method?q=get_user&q=gordon
const ARG_URL_KEY = "q"
func URLToCall(u *url.URL) (method string, args []string) {
return path.Base(u.Path), u.Query()[ARG_URL_KEY]
}
func ListenAndServeHTTP(addr string, service Service) error {
return http.ListenAndServe(addr, http.HandlerFunc(
func (w http.ResponseWriter, r *http.Request) {
cmd, args := URLToCall(r.URL)
if err := call(service, r.Body, &AutoFlush{w}, append([]string{cmd}, args...)...); err != nil {
fmt.Fprintf(w, "Error: " + err.Error() + "\n")
}
}))
}
type AutoFlush struct {
http.ResponseWriter
}
func (w *AutoFlush) Write(data []byte) (int, error) {
ret, err := w.ResponseWriter.Write(data)
if flusher, ok := w.ResponseWriter.(http.Flusher); ok {
flusher.Flush()
}
return ret, err
}

62
rcli/tcp.go Normal file
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@ -0,0 +1,62 @@
package rcli
import (
"io"
"io/ioutil"
"net"
"log"
"fmt"
"encoding/json"
"bufio"
)
func CallTCP(addr string, args ...string) (io.ReadWriteCloser, error) {
cmd, err := json.Marshal(args)
if err != nil {
return nil, err
}
conn, err := net.Dial("tcp", addr)
if err != nil {
return nil, err
}
if _, err := fmt.Fprintln(conn, string(cmd)); err != nil {
return nil, err
}
return conn, nil
}
func ListenAndServeTCP(addr string, service Service) error {
listener, err := net.Listen("tcp", addr)
if err != nil {
return err
}
defer listener.Close()
for {
if conn, err := listener.Accept(); err != nil {
return err
} else {
go func() {
if err := Serve(conn, service); err != nil {
log.Printf("Error: " + err.Error() + "\n")
fmt.Fprintf(conn, "Error: " + err.Error() + "\n")
}
conn.Close()
}()
}
}
return nil
}
func Serve(conn io.ReadWriter, service Service) error {
r := bufio.NewReader(conn)
var args []string
if line, err := r.ReadString('\n'); err != nil {
return err
} else if err := json.Unmarshal([]byte(line), &args); err != nil {
return err
} else {
return call(service, ioutil.NopCloser(r), conn, args...)
}
return nil
}

84
rcli/types.go Normal file
View File

@ -0,0 +1,84 @@
package rcli
import (
"fmt"
"io"
"reflect"
"flag"
"log"
"strings"
"errors"
)
type Service interface {
Name() string
Help() string
}
type Cmd func(io.ReadCloser, io.Writer, ...string) error
type CmdMethod func(Service, io.ReadCloser, io.Writer, ...string) error
func call(service Service, stdin io.ReadCloser, stdout io.Writer, args ...string) error {
flags := flag.NewFlagSet("main", flag.ContinueOnError)
flags.SetOutput(stdout)
flags.Usage = func() { stdout.Write([]byte(service.Help())) }
if err := flags.Parse(args); err != nil {
return err
}
cmd := flags.Arg(0)
log.Printf("%s\n", strings.Join(append(append([]string{service.Name()}, cmd), flags.Args()[1:]...), " "))
if cmd == "" {
cmd = "help"
}
method := getMethod(service, cmd)
if method != nil {
return method(stdin, stdout, args[1:]...)
}
return errors.New("No such command: " + cmd)
}
func getMethod(service Service, name string) Cmd {
if name == "help" {
return func(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
if len(args) == 0 {
stdout.Write([]byte(service.Help()))
} else {
if method := getMethod(service, args[0]); method == nil {
return errors.New("No such command: " + args[0])
} else {
method(stdin, stdout, "--help")
}
}
return nil
}
}
methodName := "Cmd"+strings.ToUpper(name[:1])+strings.ToLower(name[1:])
method, exists := reflect.TypeOf(service).MethodByName(methodName)
if !exists {
return nil
}
return func(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
ret := method.Func.CallSlice([]reflect.Value{
reflect.ValueOf(service),
reflect.ValueOf(stdin),
reflect.ValueOf(stdout),
reflect.ValueOf(args),
})[0].Interface()
if ret == nil {
return nil
}
return ret.(error)
}
}
func Subcmd(output io.Writer, name, signature, description string) *flag.FlagSet {
flags := flag.NewFlagSet(name, flag.ContinueOnError)
flags.SetOutput(output)
flags.Usage = func() {
fmt.Fprintf(output, "\nUsage: docker %s %s\n\n%s\n\n", name, signature, description)
flags.PrintDefaults()
}
return flags
}