Add 'kpod login' and 'kpod logout' commands

Signed-off-by: umohnani8 <umohnani@redhat.com>

cmd/kpod/login.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/containers/image/docker"
+	"github.com/containers/image/pkg/docker/config"
+	"github.com/kubernetes-incubator/cri-o/libpod/common"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+	"golang.org/x/crypto/ssh/terminal"
+)
+
+var (
+	loginFlags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "password, p",
+			Usage: "Password for registry",
+		},
+		cli.StringFlag{
+			Name:  "username, u",
+			Usage: "Username for registry",
+		},
+		cli.StringFlag{
+			Name:  "authfile",
+			Usage: "Path of the authentication file. Default is ${XDG_RUNTIME_DIR}/containers/auth.json",
+		},
+	}
+	loginDescription = "Login to a container registry on a specified server."
+	loginCommand     = cli.Command{
+		Name:        "login",
+		Usage:       "login to a container registry",
+		Description: loginDescription,
+		Flags:       loginFlags,
+		Action:      loginCmd,
+		ArgsUsage:   "REGISTRY",
+	}
+)
+
+// loginCmd uses the authentication package to store a user's authenticated credentials
+// in an auth.json file for future use
+func loginCmd(c *cli.Context) error {
+	args := c.Args()
+	if len(args) > 1 {
+		return errors.Errorf("too many arguments, login takes only 1 argument")
+	}
+	if len(args) == 0 {
+		return errors.Errorf("registry must be given")
+	}
+	var server string
+	if len(args) == 1 {
+		server = args[0]
+	}
+
+	sc := common.GetSystemContext("", c.String("authfile"))
+
+	// username of user logged in to server (if one exists)
+	userFromAuthFile := config.GetUserLoggedIn(sc, server)
+	username, password, err := getUserAndPass(c.String("username"), c.String("password"), userFromAuthFile)
+	if err != nil {
+		return errors.Wrapf(err, "error getting username and password")
+	}
+
+	if err = docker.CheckAuth(context.TODO(), sc, username, password, server); err == nil {
+		if err := config.SetAuthentication(sc, server, username, password); err != nil {
+			return err
+		}
+	}
+	switch err {
+	case nil:
+		fmt.Println("Login Succeeded!")
+		return nil
+	case docker.ErrUnauthorizedForCredentials:
+		return errors.Errorf("error logging into %q: invalid username/password\n", server)
+	default:
+		return errors.Wrapf(err, "error authenticating creds for %q", server)
+	}
+}
+
+// getUserAndPass gets the username and password from STDIN if not given
+// using the -u and -p flags
+func getUserAndPass(username, password, userFromAuthFile string) (string, string, error) {
+	var err error
+	reader := bufio.NewReader(os.Stdin)
+	if username == "" {
+		if userFromAuthFile != "" {
+			fmt.Printf("Username (%s): ", userFromAuthFile)
+		} else {
+			fmt.Print("Username: ")
+		}
+		username, err = reader.ReadString('\n')
+		if err != nil {
+			return "", "", errors.Wrapf(err, "error reading username")
+		}
+	}
+	if password == "" {
+		fmt.Print("Password: ")
+		pass, err := terminal.ReadPassword(0)
+		if err != nil {
+			return "", "", errors.Wrapf(err, "error reading password")
+		}
+		password = string(pass)
+		fmt.Println()
+	}
+	return strings.TrimSpace(username), password, err
+}

cmd/kpod/logout.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/containers/image/pkg/docker/config"
+	"github.com/kubernetes-incubator/cri-o/libpod/common"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+)
+
+var (
+	logoutFlags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "authfile",
+			Usage: "Path of the authentication file. Default is ${XDG_RUNTIME_DIR}/containers/auth.json",
+		},
+		cli.BoolFlag{
+			Name:  "all, a",
+			Usage: "Remove the cached credentials for all registries in the auth file",
+		},
+	}
+	logoutDescription = "Remove the cached username and password for the registry."
+	logoutCommand     = cli.Command{
+		Name:        "logout",
+		Usage:       "logout of a container registry",
+		Description: logoutDescription,
+		Flags:       logoutFlags,
+		Action:      logoutCmd,
+		ArgsUsage:   "REGISTRY",
+	}
+)
+
+// logoutCmd uses the authentication package to remove the authenticated of a registry
+// stored in the auth.json file
+func logoutCmd(c *cli.Context) error {
+	args := c.Args()
+	if len(args) > 1 {
+		return errors.Errorf("too many arguments, logout takes only 1 argument")
+	}
+	var server string
+	if len(args) == 1 {
+		server = args[0]
+	}
+
+	sc := common.GetSystemContext("", c.String("authfile"))
+
+	if c.Bool("all") {
+		if err := config.RemoveAllAuthentication(sc); err != nil {
+			return err
+		}
+		fmt.Println("Remove login credentials for all registries")
+		return nil
+	}
+
+	err := config.RemoveAuthentication(sc, server)
+	switch err {
+	case nil:
+		fmt.Printf("Remove login credentials for %s\n", server)
+		return nil
+	case config.ErrNotLoggedIn:
+		return errors.Errorf("Not logged into %s\n", server)
+	default:
+		return errors.Wrapf(err, "error logging out of %q", server)
+	}
+}

cmd/kpod/main.go

@@ -39,6 +39,8 @@ func main() {
 		inspectCommand,
 		killCommand,
 		loadCommand,
+		loginCommand,
+		logoutCommand,
 		logsCommand,
 		mountCommand,
 		pauseCommand,