Merge pull request docker#284 from thaJeztah/various_cleanups

Assorted improvements, and add  "--version, -v", and "--help, -h" flags

Author: thaJeztah

client/client.go

@@ -26,7 +26,7 @@ func isValidCredsMessage(msg string) error {
 
 // Store uses an external program to save credentials.
 func Store(program ProgramFunc, creds *credentials.Credentials) error {
-	cmd := program("store")
+	cmd := program(credentials.ActionStore)
 
 	buffer := new(bytes.Buffer)
 	if err := json.NewEncoder(buffer).Encode(creds); err != nil {
@@ -50,7 +50,7 @@ func Store(program ProgramFunc, creds *credentials.Credentials) error {
 
 // Get executes an external program to get the credentials from a native store.
 func Get(program ProgramFunc, serverURL string) (*credentials.Credentials, error) {
-	cmd := program("get")
+	cmd := program(credentials.ActionGet)
 	cmd.Input(strings.NewReader(serverURL))
 
 	out, err := cmd.Output()
@@ -81,7 +81,7 @@ func Get(program ProgramFunc, serverURL string) (*credentials.Credentials, error
 
 // Erase executes a program to remove the server credentials from the native store.
 func Erase(program ProgramFunc, serverURL string) error {
-	cmd := program("erase")
+	cmd := program(credentials.ActionErase)
 	cmd.Input(strings.NewReader(serverURL))
 	out, err := cmd.Output()
 	if err != nil {
@@ -99,7 +99,7 @@ func Erase(program ProgramFunc, serverURL string) error {
 
 // List executes a program to list server credentials in the native store.
 func List(program ProgramFunc) (map[string]string, error) {
-	cmd := program("list")
+	cmd := program(credentials.ActionList)
 	cmd.Input(strings.NewReader("unused"))
 	out, err := cmd.Output()
 	if err != nil {

client/client_test.go

@@ -21,14 +21,14 @@ const (
 var errProgramExited = fmt.Errorf("exited 1")
 
 // mockProgram simulates interactions between the docker client and a remote
-// credentials helper.
+// credentials-helper.
 // Unit tests inject this mocked command into the remote to control execution.
 type mockProgram struct {
 	arg   string
 	input io.Reader
 }
 
-// Output returns responses from the remote credentials helper.
+// Output returns responses from the remote credentials-helper.
 // It mocks those responses based in the input in the mock.
 func (m *mockProgram) Output() ([]byte, error) {
 	in, err := io.ReadAll(m.input)
@@ -80,7 +80,7 @@ func (m *mockProgram) Output() ([]byte, error) {
 	return []byte(fmt.Sprintf("unknown argument %q with %q", m.arg, inS)), errProgramExited
 }
 
-// Input sets the input to send to a remote credentials helper.
+// Input sets the input to send to a remote credentials-helper.
 func (m *mockProgram) Input(in io.Reader) {
 	m.input = in
 }
@@ -92,16 +92,16 @@ func mockProgramFn(args ...string) Program {
 }
 
 func ExampleStore() {
-	p := NewShellProgramFunc("docker-credential-secretservice")
+	p := NewShellProgramFunc("docker-credential-pass")
 
 	c := &credentials.Credentials{
-		ServerURL: "https://example.com",
-		Username:  "calavera",
+		ServerURL: "https://registry.example.com",
+		Username:  "exampleuser",
 		Secret:    "my super secret token",
 	}
 
 	if err := Store(p, c); err != nil {
-		fmt.Println(err)
+		_, _ = fmt.Println(err)
 	}
 }
 
@@ -129,14 +129,14 @@ func TestStore(t *testing.T) {
 }
 
 func ExampleGet() {
-	p := NewShellProgramFunc("docker-credential-secretservice")
+	p := NewShellProgramFunc("docker-credential-pass")
 
-	creds, err := Get(p, "https://example.com")
+	creds, err := Get(p, "https://registry.example.com")
 	if err != nil {
-		fmt.Println(err)
+		_, _ = fmt.Println(err)
 	}
 
-	fmt.Printf("Got credentials for user `%s` in `%s`\n", creds.Username, creds.ServerURL)
+	_, _ = fmt.Printf("Got credentials for user `%s` in `%s`\n", creds.Username, creds.ServerURL)
 }
 
 func TestGet(t *testing.T) {
@@ -190,10 +190,10 @@ func TestGet(t *testing.T) {
 }
 
 func ExampleErase() {
-	p := NewShellProgramFunc("docker-credential-secretservice")
+	p := NewShellProgramFunc("docker-credential-pass")
 
-	if err := Erase(p, "https://example.com"); err != nil {
-		fmt.Println(err)
+	if err := Erase(p, "https://registry.example.com"); err != nil {
+		_, _ = fmt.Println(err)
 	}
 }
 

client/command.go

@@ -1,7 +1,6 @@
 package client
 
 import (
-	"fmt"
 	"io"
 	"os"
 	"os/exec"
@@ -30,27 +29,26 @@ func NewShellProgramFuncWithEnv(name string, env *map[string]string) ProgramFunc
 
 func createProgramCmdRedirectErr(commandName string, args []string, env *map[string]string) *exec.Cmd {
 	programCmd := exec.Command(commandName, args...)
-	programCmd.Env = os.Environ()
 	if env != nil {
 		for k, v := range *env {
-			programCmd.Env = append(programCmd.Env, fmt.Sprintf("%s=%s", k, v))
+			programCmd.Env = append(programCmd.Environ(), k+"="+v)
 		}
 	}
 	programCmd.Stderr = os.Stderr
 	return programCmd
 }
 
-// Shell invokes shell commands to talk with a remote credentials helper.
+// Shell invokes shell commands to talk with a remote credentials-helper.
 type Shell struct {
 	cmd *exec.Cmd
 }
 
-// Output returns responses from the remote credentials helper.
+// Output returns responses from the remote credentials-helper.
 func (s *Shell) Output() ([]byte, error) {
 	return s.cmd.Output()
 }
 
-// Input sets the input to send to a remote credentials helper.
+// Input sets the input to send to a remote credentials-helper.
 func (s *Shell) Input(in io.Reader) {
 	s.cmd.Stdin = in
 }

credentials/credentials.go

@@ -10,6 +10,20 @@ import (
 	"strings"
 )
 
+// Action defines the name of an action (sub-command) supported by a
+// credential-helper binary. It is an alias for "string", and mostly
+// for convenience.
+type Action = string
+
+// List of actions (sub-commands) supported by credential-helper binaries.
+const (
+	ActionStore   Action = "store"
+	ActionGet     Action = "get"
+	ActionErase   Action = "erase"
+	ActionList    Action = "list"
+	ActionVersion Action = "version"
+)
+
 // Credentials holds the information shared between docker and the credentials store.
 type Credentials struct {
 	ServerURL string
@@ -43,42 +57,52 @@ func SetCredsLabel(label string) {
 	CredsLabel = label
 }
 
-// Serve initializes the credentials helper and parses the action argument.
+// Serve initializes the credentials-helper and parses the action argument.
 // This function is designed to be called from a command line interface.
 // It uses os.Args[1] as the key for the action.
 // It uses os.Stdin as input and os.Stdout as output.
 // This function terminates the program with os.Exit(1) if there is an error.
 func Serve(helper Helper) {
-	var err error
 	if len(os.Args) != 2 {
-		err = fmt.Errorf("Usage: %s <store|get|erase|list|version>", os.Args[0])
+		_, _ = fmt.Fprintln(os.Stdout, usage())
+		os.Exit(1)
 	}
 
-	if err == nil {
-		err = HandleCommand(helper, os.Args[1], os.Stdin, os.Stdout)
+	switch os.Args[1] {
+	case "--version", "-v":
+		_ = PrintVersion(os.Stdout)
+		os.Exit(0)
+	case "--help", "-h":
+		_, _ = fmt.Fprintln(os.Stdout, usage())
+		os.Exit(0)
 	}
 
-	if err != nil {
-		fmt.Fprintf(os.Stdout, "%v\n", err)
+	if err := HandleCommand(helper, os.Args[1], os.Stdin, os.Stdout); err != nil {
+		_, _ = fmt.Fprintln(os.Stdout, err)
 		os.Exit(1)
 	}
 }
 
-// HandleCommand uses a helper and a key to run a credential action.
-func HandleCommand(helper Helper, key string, in io.Reader, out io.Writer) error {
-	switch key {
-	case "store":
+func usage() string {
+	return fmt.Sprintf("Usage: %s <store|get|erase|list|version>", Name)
+}
+
+// HandleCommand runs a helper to execute a credential action.
+func HandleCommand(helper Helper, action Action, in io.Reader, out io.Writer) error {
+	switch action {
+	case ActionStore:
 		return Store(helper, in)
-	case "get":
+	case ActionGet:
 		return Get(helper, in, out)
-	case "erase":
+	case ActionErase:
 		return Erase(helper, in)
-	case "list":
+	case ActionList:
 		return List(helper, out)
-	case "version":
+	case ActionVersion:
 		return PrintVersion(out)
+	default:
+		return fmt.Errorf("%s: unknown action: %s", Name, action)
 	}
-	return fmt.Errorf("Unknown credential action `%s`", key)
 }
 
 // Store uses a helper and an input reader to save credentials.
@@ -132,18 +156,17 @@ func Get(helper Helper, reader io.Reader, writer io.Writer) error {
 		return err
 	}
 
-	resp := Credentials{
+	buffer.Reset()
+	err = json.NewEncoder(buffer).Encode(Credentials{
 		ServerURL: serverURL,
 		Username:  username,
 		Secret:    secret,
-	}
-
-	buffer.Reset()
-	if err := json.NewEncoder(buffer).Encode(resp); err != nil {
+	})
+	if err != nil {
 		return err
 	}
 
-	fmt.Fprint(writer, buffer.String())
+	_, _ = fmt.Fprint(writer, buffer.String())
 	return nil
 }
 
@@ -181,6 +204,6 @@ func List(helper Helper, writer io.Writer) error {
 
 // PrintVersion outputs the current version.
 func PrintVersion(writer io.Writer) error {
-	fmt.Fprintf(writer, "%s (%s) %s\n", Name, Package, Version)
+	_, _ = fmt.Fprintf(writer, "%s (%s) %s\n", Name, Package, Version)
 	return nil
 }