user.go

// -*- Mode: Go; indent-tabs-mode: t -*-

/*
 * Copyright (C) 2014-2015 Canonical Ltd
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package osutil

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"regexp"
	"strings"
)

var userLookup = user.Lookup

func AddExtraUser(name string, sshKeys []string, gecos string) error {
	// we check the (user)name ourselfs, adduser is a bit too
	// strict (i.e. no `.`)
	validNames := regexp.MustCompile(`^[a-z][-a-z0-9_.]*$`)
	if !validNames.MatchString(name) {
		return fmt.Errorf("cannot add user %q: name contains invalid charackters", name)
	}

	cmd := exec.Command("adduser", "--force-badname", "--gecos", gecos, "--extrausers", "--disabled-password", name)
	if output, err := cmd.CombinedOutput(); err != nil {
		return fmt.Errorf("adduser failed with %s: %s", err, output)
	}

	u, err := userLookup(name)
	if err != nil {
		return fmt.Errorf("cannot find user %q: %s", name, err)
	}
	sshDir := filepath.Join(u.HomeDir, ".ssh")
	if err := os.MkdirAll(sshDir, 0700); err != nil {
		return fmt.Errorf("cannot create %s: %s", sshDir, err)
	}
	authKeys := filepath.Join(sshDir, "authorized_keys")
	authKeysContent := strings.Join(sshKeys, "\n")
	if err := ioutil.WriteFile(authKeys, []byte(authKeysContent), 0644); err != nil {
		return fmt.Errorf("cannot write %s: %s", authKeys, err)
	}

	return nil
}