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 (with the given key_options) should or should not be in the file
    required: false
    choices: [ "present", "absent" ]
    default: "present"
  key_options:
    description:
      - A string of ssh key options to be prepended to the key in the authorized_keys file
    required: false
    default: null
    version_added: "1.4"
  unique:
    description:
      - Ensure that there is only one key matching the specified key in the file
    required: false
    default: false
    version_added: "1.4"
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

# Using with_file
- name: Set up authorized_keys for the deploy user
  authorized_key: user=deploy
                  key="{{ item }}"
  with_file:
    - public_keys/doe-jane
    - public_keys/doe-john

# Using key_options:
- authorized_key: user=charlie
                  key="{{ lookup('file', '/home/charlie/.ssh/id_rsa.pub') }}"
                  key_options='no-port-forwarding,host="10.0.1.1"'
'''

# 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 shlex

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 parseoptions(options):
    ''' 
    reads a string containing ssh-key options 
    and returns a dictionary of those options
    '''
    options_dict = {}
    if options:
        options_list = options.strip().split(",")
        for option in options_list:
            if option.find("=") != -1:
                (arg,val) = option.split("=", 1)
            else:
                arg = option
                val = None
            options_dict[arg] = val
    return options_dict

def parsekey(raw_key):
    '''
    parses a key, which may or may not contain a list
    of ssh-key options at the beginning
    '''

    key_parts = shlex.split(raw_key)
    if len(key_parts) == 4:
        # this line contains options
        (options,type,key,comment) = key_parts
    elif len(key_parts) == 3:
        # this line is just 'type key user@host'
        (type,key,comment) = key_parts
        options = None
    else:
        # invalid key, maybe a comment?
        return None

    if options:
        # parse the options and store them
        options = parseoptions(options)
    return (key, type, options, comment)

def readkeys(filename):

    if not os.path.isfile(filename):
        return []

    keys = []
    f = open(filename)
    for line in f.readlines():
        key_data = parsekey(line)
        if key_data:
            keys.append(key_data)
        else:
            # for an invalid line, just append the line
            # to the array so it will be re-output later
            keys.append(line)
    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:
        for key in keys:
            try:
                (keyhash,type,options,comment) = key
                option_str = ""
                if options:
                    for option_key in options.keys():
                        if options[option_key]:
                            option_str += "%s=%s " % (option_key, options[option_key])
                        else:
                            option_str += "%s " % option_key
                key_line = "%s%s %s %s\n" % (option_str, type, keyhash, comment)
            except:
                key_line = key
            f.writelines(key_line)
    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_options = params.get("key_options", None)
    unique      = params.get("unique",False)

    key = key.split('\n')

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

    # Check our new keys, if any of them exist we'll continue.
    for new_key in key:
        if key_options is not None:
            new_key = "%s %s" % (key_options, new_key)

        parsed_new_key = parsekey(new_key)
        if not parsed_new_key:
            module.fail_json(msg="invalid key specified: %s" % new_key)

        present = False
        matched = False
        non_matching_keys = []
        for existing_key in existing_keys:
            # skip bad entries or bad input
            if len(parsed_new_key) == 0 or len(existing_key) == 0:
                continue
            # the first element in the array after parsing
            # is the actual key hash, which we check first
            if parsed_new_key[0] == existing_key[0]:
                present = True
                # Then we check if everything matches, including
                # the key type and options. If not, we append this
                # existing key to the non-matching list
                if parsed_new_key != existing_key:
                    non_matching_keys.append(existing_key)
                else:
                    matched = True

        # handle idempotent state=present
        if state=="present":
            if unique and len(non_matching_keys) > 0:
                for non_matching_key in non_matching_keys:
                    existing_keys.remove(non_matching_key)
                do_write = True

            if not matched:
                existing_keys.append(parsed_new_key)
                do_write = True

        elif state=="absent":
            # currently, we only remove keys when 
            # they are an exact match
            if not matched:
                continue
            existing_keys.remove(parsed_new_key)
            do_write = True

    if do_write:
        writekeys(module, keyfile(module, user, do_write, path, manage_dir), existing_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']),
           key_options = dict(required=False, type='str'),
           unique      = dict(default=False, type='bool'),
        )
    )

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

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