ansible/library/system/authorized_key

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
Ansible module to add authorized_keys for ssh logins.
(c) 2012, Brad Olson <brado@movedbylight.com>

This file is part of Ansible

Ansible is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
"""

DOCUMENTATION = '''
---
module: authorized_key
short_description: Adds or removes an SSH authorized key
description:
     - Adds or removes an SSH authorized key for a user from a remote host.
version_added: "0.5"
options:
  user:
    description:
      - The username on the remote host whose authorized_keys file will be modified
    required: true
    default: null
    aliases: []
  key:
    description:
      - The SSH public key, as a string
    required: true
    default: null
  path:
    description:
      - Alternate path to the authorized_keys file
    required: false
    default: "(homedir)+/.ssh/authorized_keys"
    version_added: "1.2"
  manage_dir:
    description:
      - Whether this module should manage the directory of the authorized_keys file
    required: false
    choices: [ "yes", "no" ]
    default: "yes"
    version_added: "1.2"
  state:
    description:
      - Whether the given key should or should not be in the file
    required: false
    choices: [ "present", "absent" ]
    default: "present"
description:
    - "Adds or removes authorized keys for particular user accounts"
author: Brad Olson
'''

EXAMPLES = '''
# Example using key data from a local file on the management machine
- authorized_key: user=charlie key="{{ lookup('file', '/home/charlie/.ssh/id_rsa.pub') }}"

# Using alternate directory locations:
- authorized_key: user=charlie
                  key="{{ lookup('file', '/home/charlie/.ssh/id_rsa.pub') }}"
                  path='/etc/ssh/authorized_keys/charlie'
                  manage_dir=no
'''

# Makes sure the public key line is present or absent in the user's .ssh/authorized_keys.
#
# Arguments
# =========
#    user = username
#    key = line to add to authorized_keys for user
#    path = path to the user's authorized_keys file (default: ~/.ssh/authorized_keys)
#    manage_dir = whether to create, and control ownership of the directory (default: true)
#    state = absent|present (default: present)
#
# see example in examples/playbooks

import sys
import os
import pwd
import os.path
import tempfile
import shutil

def keyfile(module, user, write=False, path=None, manage_dir=True):
    """
    Calculate name of authorized keys file, optionally creating the
    directories and file, properly setting permissions.

    :param str user: name of user in passwd file
    :param bool write: if True, write changes to authorized_keys file (creating directories if needed)
    :param str path: if not None, use provided path rather than default of '~user/.ssh/authorized_keys'
    :param bool manage_dir: if True, create and set ownership of the parent dir of the authorized_keys file
    :return: full path string to authorized_keys for user
    """

    try:
        user_entry = pwd.getpwnam(user)
    except KeyError, e:
        module.fail_json(msg="Failed to lookup user %s: %s" % (user, str(e)))
    if path is None:
        homedir    = user_entry.pw_dir
        sshdir     = os.path.join(homedir, ".ssh")
        keysfile   = os.path.join(sshdir, "authorized_keys")
    else:
        sshdir     = os.path.dirname(path)
        keysfile   = path

    if not write:
        return keysfile

    uid = user_entry.pw_uid
    gid = user_entry.pw_gid

    if manage_dir in BOOLEANS_TRUE:
        if not os.path.exists(sshdir):
            os.mkdir(sshdir, 0700)
            if module.selinux_enabled():
                module.set_default_selinux_context(sshdir, False)
        os.chown(sshdir, uid, gid)
        os.chmod(sshdir, 0700)

    if not os.path.exists(keysfile):
        basedir = os.path.dirname(keysfile)
        if not os.path.exists(basedir):
            os.makedirs(basedir)
        try:
            f = open(keysfile, "w") #touches file so we can set ownership and perms
        finally:
            f.close()
        if module.selinux_enabled():
            module.set_default_selinux_context(keysfile, False)

    try:
        os.chown(keysfile, uid, gid)
        os.chmod(keysfile, 0600)
    except OSError:
        pass

    return keysfile

def readkeys(filename):

    if not os.path.isfile(filename):
        return []
    f = open(filename)
    keys = [line.rstrip() for line in f.readlines()]
    f.close()
    return keys

def writekeys(module, filename, keys):

    fd, tmp_path = tempfile.mkstemp('', 'tmp', os.path.dirname(filename))
    f = open(tmp_path,"w")
    try:
        f.writelines( (key + "\n" for key in keys) )
    except IOError, e:
        module.fail_json(msg="Failed to write to file %s: %s" % (tmp_path, str(e)))
    f.close()
    module.atomic_move(tmp_path, filename)

def enforce_state(module, params):
    """
    Add or remove key.
    """

    user       = params["user"]
    key        = params["key"]
    path       = params.get("path", None)
    manage_dir = params.get("manage_dir", True)
    state      = params.get("state", "present")

    key = key.split('\n')

    # check current state -- just get the filename, don't create file
    write = False
    params["keyfile"] = keyfile(module, user, write, path, manage_dir)
    keys = readkeys(params["keyfile"])

    # Check our new keys, if any of them exist we'll continue.
    for new_key in key:
        present = new_key in keys
        # handle idempotent state=present
        if state=="present":
            if present:
                continue
            keys.append(new_key)
            write = True
            writekeys(module, keyfile(module, user, write, path, manage_dir), keys)
            params['changed'] = True

        elif state=="absent":
            if not present:
                continue
            keys.remove(new_key)
            write = True
            writekeys(module, keyfile(module, user, write, path, manage_dir), keys)
            params['changed'] = True

    return params

def main():

    module = AnsibleModule(
        argument_spec = dict(
           user       = dict(required=True, type='str'),
           key        = dict(required=True, type='str'),
           path       = dict(required=False, type='str'),
           manage_dir = dict(required=False, type='bool', default=True),
           state      = dict(default='present', choices=['absent','present'])
        )
    )

    results = enforce_state(module, module.params)
    module.exit_json(**results)

# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
main()