Merge pull request #270 from tych0/warn-only-about-password-on-cli

login: print a big warning when using --password

cli/command/registry/login.go

@@ -47,6 +47,10 @@ func runLogin(dockerCli command.Cli, opts loginOptions) error {
 	ctx := context.Background()
 	clnt := dockerCli.Client()
 
+	if opts.password != "" {
+		fmt.Fprintln(dockerCli.Err(), "WARNING! Using --password via the CLI is insecure.")
+	}
+
 	var (
 		serverAddress string
 		authServer    = command.ElectAuthServer(ctx, dockerCli)