cloudinit/system/ssh_key.go

/*
   Copyright 2014 CoreOS, Inc.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package system

import (
	"fmt"
	"io"
	"io/ioutil"
	"os/exec"
	"strings"
)

// Add the provide SSH public key to the core user's list of
// authorized keys
func AuthorizeSSHKeys(user string, keysName string, keys []string) error {
	for i, key := range keys {
		keys[i] = strings.TrimSpace(key)
	}

	// join all keys with newlines, ensuring the resulting string
	// also ends with a newline
	joined := fmt.Sprintf("%s\n", strings.Join(keys, "\n"))

	cmd := exec.Command("update-ssh-keys", "-u", user, "-a", keysName)
	stdin, err := cmd.StdinPipe()
	if err != nil {
		return err
	}

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return err
	}

	stderr, err := cmd.StderrPipe()
	if err != nil {
		return err
	}

	err = cmd.Start()
	if err != nil {
		stdin.Close()
		return err
	}

	_, err = io.WriteString(stdin, joined)
	if err != nil {
		return err
	}

	stdin.Close()
	stdoutBytes, _ := ioutil.ReadAll(stdout)
	stderrBytes, _ := ioutil.ReadAll(stderr)

	err = cmd.Wait()
	if err != nil {
		return fmt.Errorf("Call to update-ssh-keys failed with %v: %s %s", err, string(stdoutBytes), string(stderrBytes))
	}

	return nil
}